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Mariner 2

Mariner 2

Mariner 2, a space probe to Venus, was the first successful spacecraft in the NASA Mariner program. The Mariner 1 and 2 spacecraft were simplified versions of the Block I spacecraft of the Ranger program. The Mariner probe consisted of a 100 cm diameter hexagonal bus, to which solar panels, instrument booms, and antennae were attached. The scientific instruments onboard the Mariner spacecraft were two radiometers (microwave and infrared) mounted on a tilting platform, a micrometeorite sensor, a solar plasma sensor, a charged particle sensor, and a magnetometer. These instruments were designed to measure the temperature distribution on the surface of Venus, as well as making basic measurements of Venus' atmopshere. Due to the planet's thick cloud cover, no cameras were included in the Mariner units. The Atlas-Agena rocket carrying Mariner 1 veered off-course during its launch on July 22, 1962, and the spacecraft was destroyed. A month later, the identical Mariner 2 spacecraft was launched successfully on August 27, 1962, sending it on a 3½-month flight to Venus. On the way it measured for the first time the solar wind, a constant stream of charged particles flowing outwards from the Sun. It also measured interplanetary dust, which turned out to be more scarce than predicted. In addition, Mariner 2 detected high-energy charged particles coming from the Sun, including several brief solar flares, as well as cosmic rays from outside the Solar system. As it flew by Venus on December 14, 1962, Mariner 2 scanned the planet with its pair of radiometers, revealing that Venus has cool clouds and an extremely hot surface. The spacecraft is now defunct in a heliocentric orbit.

Detailed Description

The Mariner 2 spacecraft was the second of a series of spacecraft used for planetary exploration in the flyby, or nonlanding, mode and the first spacecraft to successfully encounter another planet. Mariner 2 was a backup for the Mariner 1 mission which failed shortly after launch to Venus. The objective of the Mariner 2 mission was to fly by Venus and return data on the planet's atmosphere, magnetic field, charged particle environment, and mass. It also made measurements of the interplanetary medium during its cruise to Venus and after the flyby.

Spacecraft and Subsystems

Mariner 2 consisted of a hexagonal base, 1.04 meters across and 0.36 meters thick, which contained six magnesium chassis housing the electronics for the science experiments, communications, data encoding, computing, timing, and attitude control, and the power control, battery, and battery charger, as well as the attitude control gas bottles and the rocket engine. On top of the base was a tall pyramid-shaped mast on which the science experiments were mounted which brought the total height of the spacecraft to 3.66 meters. Attached to either side of the base were rectangular solar panel wings with a total span of 5.05 meters and width of 0.76 meters. Attached by an arm to one side of the base and extending below the spacecraft was a large directional dish antenna. The Mariner 2 power system consisted of the two solar cell wings, one 183 cm by 76 cm and the other 152 cm by 76 cm (with a 31 cm dacron extension (a solar sail) to balance the solar pressure on the panels) which powered the craft directly or recharged a 1000 Watt-hour sealed silver-zinc cell battery, which was used before the panels were deployed, when the panels were not illuminated by the Sun, and when loads were heavy. A power-switching and booster regulator device controlled the power flow. Communications consisted of a 3 Watt transmitter capable of continuous telemetry operation, the large high gain directional dish antenna, a cylindrical omnidirectional antenna at the top of the instrument mast, and two command antennas, one on the end of either solar panel, which received instructions for midcourse maneuvers and other functions. Propulsion for midcourse maneuvers was supplied by a monopropellant (anhydrous hydrazine) 225 N retro-rocket. The hydrazine was ignited using nitrogen tetroxide and aluminum oxide pellets, and thrust direction was controlled by four jet vanes situated below the thrust chamber. Attitude control with a 1 degree pointing error was maintained by a system of nitrogen gas jets. The Sun and Earth were used as references for attitude stabilization. Overall timing and control was performed by a digital Central Computer and Sequencer. Thermal control was achieved through the use of passive reflecting and absorbing surfaces, thermal shields, and movable louvers. The scientific experiments were mounted on the instrument mast and base. A magnetometer was attached to the top of the mast below the omnidirectional antenna. Particle detectors were mounted halfway up the mast, along with the cosmic ray detector. A cosmic dust detector and solar plasma spectrometer detector were attached to the top edges of the spacecraft base. A microwave radiometer and an infrared radiometer and the radiometer reference horns were rigidly mounted to a 48 cm diameter parabolic radiometer antenna mounted near the bottom of the mast. All instruments were operated throughout the cruise and encounter modes except the radiometers, which were only used in the immediate vicinity of Venus.

Mission Profile

After launch and termination of the Agena first burn, the Agena-Mariner was in a 118 km altitude Earth parking orbit. The Agena second burn some 980 seconds later followed by Agena-Mariner separation injected the Mariner 2 spacecraft into a geocentric escape hyperbola at 26 minutes 3 seconds after lift-off. Solar panel extension was completed about 44 minutes after launch. On 29 August 1962 cruise science experiments were turned on. The midcourse maneuver was initiated at 22:49:00 UT on 4 September and completed at 2:45:25 UT 5 September. On 8 September at 17:50 UT the spacecraft suddenly lost its attitude control, which was restored by the gyroscopes 3 minutes later. The cause was unknown but may have been a collision with a small object. On October 31 the output from one solar panel deteriorated abruptly, and the science cruise instruments were turned off. A week later the panel resumed normal function and instruments were turned back on. The panel permanently failed on 15 November, but Mariner 2 was close enough to the Sun that one panel could supply adequate power. On December 14 the radiometers were turned on. Mariner 2 approached Venus from 30 degrees above the dark side of the planet, and passed below the planet at its closest distance of 34,773 km at 19:59:28 UT 14 December 1962. After encounter, cruise mode resumed. Spacecraft perihelion occurred on 27 December at a distance of 105,464,560 km. The last transmission from Mariner 2 was received on 3 January 1963 at 07:00 UT. Mariner 2 remains in heliocentric orbit.

Scientific Results

Scientific discoveries made by Mariner 2 included a slow retrograde rotation rate for Venus, hot surface temperatures and high surface pressures, a predominantly carbon dioxide atmosphere, continuous cloud cover with a top altitude of about 60 km, and no detectable magnetic field. It was also shown that in interplanetary space the solar wind streams continuously and the cosmic dust density is much lower than the near-Earth region. Improved estimates of Venus' mass and the value of the astronomical unit were made. Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.

External links


- [http://sse.jpl.nasa.gov/missions/profile.cfm?Sort=Target&Target=Venus&MCode=Mariner_02 NASA-Jet Propulsion Laboratory Guide to Mariner 2]
- [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660005413_1966005413.pdf Mariner-Venus 1962 Final project report - NASA (PDF)]
- [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19650072055_1965072055.pdf Mariner 1 and 2. tracking information memorandum - Jun 1962 (PDF)] Category:Venus spacecraft Category:Mariner program

Spacecraft

, 2004.]] A spacecraft is a vehicle that travels through space. Spacecraft include robotic or unmanned space probes as well as manned vehicles. The term is sometimes also used to describe artificial satellites, which have similar design criteria.

Overview

The term spaceship is generally applied only to spacecraft capable of transporting people. A space suit has at times been called a miniature spacecraft or spaceship, emphasizing its purpose of keeping its wearer alive while traveling in the vacuum of outer space. The spacecraft is one of the primal elements in science fiction. Numerous short stories and novels are built up around various ideas for spacecraft. Some hard science fiction books focus on the technical details of the craft, while others treat the spacecraft as a given and delve little into its actual implementation.

Examples of past or existing spacecraft

Manned
- Apollo Spacecraft
- Gemini Spacecraft
- International Space Station
- Mir
- Mercury Spacecraft
- Shuttle Buran
- Shenzhou Spacecraft
- Space Shuttle
- Soyuz Spacecraft
- SpaceShipOne
- Voskhod Spacecraft
- Vostok Spacecraft Unmanned
- Cassini-Huygens
- Cluster
- Deep Space 1
- Genesis
- Mars Exploration Rover
- Mars Global Surveyor
- Mars Pathfinder
- Pioneer 10
- Pioneer 11
- Progress
- SOHO
- Stardust
- Viking 1
- Viking 2
- Voyager 1
- Voyager 2
- WMAP

Spacecraft under development


- Crew Exploration Vehicle
- Kliper
- Automated Transfer Vehicle
- H-II Transfer Vehicle
- Ansari X Prize (incl. a list of spacecraft in various stages of completion as of 2005) The US Space Command, according to its "Long Range Plan", is currently planning to develop a weaponized spaceship, which has yet to be announced.[http://www.fas.org/spp/military/docops/usspac/]

See also


- Attitude control
- Expendable launch system
- Human spaceflight
- List of fictional spaceships
- List of spacecraft
- Spacecraft propulsion
- Space shuttle
- Starship
- Thruster
- Unidentified flying object
- Unmanned space mission

External links


- [http://science.hq.nasa.gov/missions/phase.html NASA: Space Science Spacecraft Missions]
- [http://www.skyrocket.de/space/ Gunter's Space Page - Complete information on spacecraft]
- [http://www.cinespaceships.net/ Cinespaceships - Database on spaceships in movie]
- ja:宇宙船

NASA

] The National Aeronautics and Space Administration (NASA), which was established in 1958, is the agency responsible for the public space program of the United States of America. It is also responsible for long-term civilian and military aerospace research.

Vision and mission

NASA's vision is "to improve life here, extend life to there, and to find life beyond." Its mission is "to understand and protect our home planet; to explore the Universe and search for life; and to inspire the next generation of explorers."

History

Space Race

:For additional background, please see the Space Race article Space Race launch of Redstone rocket and NASA's Mercury 3 capsule Freedom 7 with Alan Shepard Jr. on the United States' first human flight into sub-orbital space. (Atlas rockets were used to launch Mercury's orbital missions.)]] Following the Soviet space program's launch of the world's first man-made satellite (Sputnik 1) on October 4, 1957, the attention of the United States turned toward its own fledgling space efforts. The U.S. Congress, alarmed by the perceived threat to U.S. security and technological leadership, urged immediate and swift action; President Dwight D. Eisenhower and his advisers counseled more deliberate measures. Several months of debate produced agreement that a new federal agency was needed to conduct all nonmilitary activity in space. On July 29, 1958, President Eisenhower signed the National Aeronautics and Space Act of 1958 establishing the National Aeronautics and Space Administration (NASA). When it began operations on October 1, 1958, NASA consisted mainly of the four laboratories and some 8,000 employees of the government's 46-year-old research agency for aeronautics, the National Advisory Committee for Aeronautics (NACA), though the probably most important contribution actually had its roots in the German rocket program led by Wernher von Braun, who is today regarded as the father of the United States space program. NASA's early programs were research into human spaceflight, and were conducted under the pressure of the competition between the USA and the USSR (the Space Race) that existed during the Cold War. The Mercury program, initiated in 1958, started NASA down the path of human space exploration with missions designed to discover simply if man could survive in space. Representatives from the U.S. Army (M.L. Raines, LTC, USA), Navy (P.L. Havenstein, CDR, USN) and Air Force (K.G. Lindell, COL, USAF) were selected/requested to provide assistance to the NASA Space Task Group through coordination with the existing U.S. military research and defense contracting infrastructure, and technical assistance resulting from experimental aircraft (and the associated military test pilot pool) development in the 1950s. On May 5, 1961, astronaut Alan B. Shepard Jr. became the first American in space when he piloted Freedom 7 on a 15-minute suborbital flight. John Glenn became the first American to orbit the Earth on February 20, 1962 during the 5-hour flight of Friendship 7. Once the Mercury project proved that human spaceflight was possible, project Gemini was launched to conduct experiments and work out issues relating to a moon mission. The first Gemini flight with astronauts on board, Gemini III, was flown by Virgil "Gus" Grissom and John W. Young on March 23, 1965. Nine other missions followed, showing that long-duration human space flight was possible, proving that rendezvous and docking with another vehicle in space was possible, and gathering medical data on the effects of weightlessness on humans.

Apollo program

Following the success of the Mercury and Gemini programs, the Apollo program was launched to try to do interesting work in space and possibly put men around (but not on) the Moon. The direction of the Apollo program was radically altered following President John F. Kennedy's announcement on May 25, 1961 that the United States should commit itself to "landing a man on the Moon and returning him safely to the Earth" by 1970. Thus Apollo became a program to land men on the Moon. The Gemini program was started shortly thereafter to provide an interim spacecraft to prove techniques needed for the now much more complicated Apollo missions. Gemini program.]] After eight years of preliminary missions, including NASA's first loss of astronauts with the Apollo 1 launch pad fire, and the first spacecraft to orbit the Moon (Apollo 8) at the end of 1968, the Apollo program achieved its goals with Apollo 11 which landed Neil Armstrong and Buzz Aldrin on the moon's surface on July 20, 1969 and returned them to Earth safely on July 24. Armstrong's first words upon stepping out of the Eagle lander captured the momentousness of the occasion: "That's one small step for [a] man, one giant leap for mankind." Twelve men would set foot on the Moon by the end of the Apollo program in December 1972. NASA had won the moon race, and in some senses this left it without direction, or at the very least without the public attention and interest that was necessary to guarantee large budgets from Congress. After President Lyndon Johnson left office, NASA lost its main political supporter, and rocket scientist Wernher von Braun was moved to a position lobbying in Washington. Plans for ambitious follow-on projects to construct a space station, establish a lunar base and launch a human mission to Mars by 1990 were proposed but with the end to procurement of Saturn and Apollo hardware, there was no capability to support these. The near-disaster of Apollo 13, where an oxygen tank explosion nearly doomed all three astronauts, helped to recapture national attention and concern. Although missions up to Apollo 20 were planned, Apollo 17 was the last mission to fly under the Apollo banner. The program ended because of budget cuts (in part due to the Vietnam War) and the desire to develop a reusable space vehicle.

Other early missions

Although the vast majority of NASA's budget has been spent on human spaceflight, there have been many robotic missions instigated by the space agency. In 1962 the Mariner 2 mission was launched and became the first spacecraft to make a flyby of another planet – in this case Venus. The Ranger, Surveyor, and Lunar Orbiter missions were essential to assessing lunar conditions before attempting Apollo landings with humans on board. Later, the two Viking probes landed on the surface of Mars and sent color images back to Earth, but perhaps more impressive were the Pioneer and particularly Voyager missions that visited Jupiter, Saturn, Uranus and Neptune sending back scientific information and color images. Having lost the moon race, the Soviet Union had, along with the USA, changed its approach. On July 17, 1975 an Apollo craft (finding a new use after the cancelling of planned lunar flights) was docked to the Soviet Soyuz 19 spacecraft, in the Apollo-Soyuz Test Project. Although the Cold War would last many more years, this was a critical point in NASA's history and much of the international co-operation in space exploration that exists today has its genesis with this mission. America's first space station, Skylab, occupied NASA from the end of Apollo until the late 1970s.

Shuttle era

Skylab 1981 ]] The space shuttle became the major focus of NASA in the late 1970s and the 1980s. Planned to be a frequently launchable and mostly reusable vehicle, four space shuttles were built by 1985. The first to launch, Columbia did so on April 12, 1981. The shuttle was not all good news for NASA – flights were much more expensive than initially projected, and even after the 1986 Challenger disaster highlighted the risks of space flight, the public again lost interest as missions appeared to become mundane. Work began on Space Station Freedom as a focus for the manned space programme but within NASA there was argument that these projects came at the expense of more inspiring unmanned missions such as the Voyager probes. The Challenger disaster aside the late 1980s marked a low point for NASA. Nonetheless, the shuttle has been used to launch milestone projects like the Hubble Space Telescope (HST). The HST was created with a relatively small budget of $2 billion but has continued operation since 1990 and has delighted both scientists and the public. Some of the images it has returned have become near-legendary, such as the groundbreaking Hubble Deep Field images. The HST is a joint project between ESA and NASA, and its success has paved the way for greater collaboration between the agencies. In 1995 Russian-American interaction would again be achieved as the Shuttle-Mir missions began, and once more a Russian craft (this time a full-fledged space station) docked with an American vehicle. This cooperation continues to the present day, with Russia and America the two biggest partners in the largest space station ever built – the International Space Station (ISS). The strength of their cooperation on this project was even more evident when NASA began relying on Russian launch vehicles to service the ISS following the 2003 Columbia disaster, which grounded the shuttle fleet for well over two years. Costing over one hundred billion dollars, it has been difficult at times for NASA to justify the ISS. The population at large have historically been hard to impress with details of scientific experiments in space, preferring news of grand projects to exotic locations. Even now, the ISS cannot accommodate as many scientists as planned. During much of the 1990s, NASA was faced with shrinking annual budgets due to Congressional belt-tightening in Washington, DC. In response, NASA's ninth administrator, Daniel S. Goldin, pioneered the "faster, better, cheaper" approach that enabled NASA to cut costs while still delivering a wide variety of aerospace programs (Discovery Program). That method was criticized and re-evaluated following the twin losses of Mars Climate Orbiter and Mars Polar Lander in 1999.

NASA's future

Mars Polar Lander and the planned crew and heavy lift launch vehicles]] NASA's most publicly-inspiring mission of recent years has probably been the Mars Pathfinder mission of 1997. Newspapers around the world carried images of the lander dispatching its own rover, Sojourner, to explore the surface of Mars in a way never done before at any extra-terrestrial location. Less publicly acclaimed but performing science from 1997 to date (2005) has been the Mars Global Surveyor orbiter. Since 2001, the orbiting Mars Odyssey has been searching for evidence of past or present water and volcanic activity on the red planet. NASA expects to continue exploring the Red Planet with more spacecraft such as the Mars Reconnaissance Orbiter, which will reach Mars in 2006. The Space Shuttle Columbia disaster in 2003, which killed the crew of six American and one Israeli astronaut, and caused a 29-month hiatus in space shuttle flights, triggered a serious re-examination of NASA's priorities. The U.S. government, various scientists, and the public all considered the future of the space program. On January 14, 2004, ten days after the landing of Mars Exploration Rover Spirit, President George W. Bush announced a new plan for NASA's future, dubbed the Vision for Space Exploration. According to this plan, humankind will return to the moon by 2020, and set up outposts as a testbed and potential resource for future missions. The space shuttle will be retired in 2010 and the Crew Exploration Vehicle will replace it by 2014, capable of both docking with the ISS and leaving the Earth's orbit. The future of the ISS is somewhat uncertain – construction will be completed, but beyond that is less clear. Although the plan initially met with skepticism from Congress, in late 2004 Congress agreed to provide start-up funds for the first year's worth of the new space vision. Hoping to spur innovation from the private sector, NASA established a series of Centennial Challenges, technology prizes for non-government teams, in 2004. The Challenges include tasks that will be useful for implementing the Vision for Space Exploration, such as building more efficient astronaut gloves.

Criticisms

Some commentators, such as Mark Wade, note that NASA has suffered from a 'stop-start' approach to its human spaceflight programs. The Apollo spacecraft and Saturn family of launch vehicles were abandoned in 1970 after billions of dollars had been spent on their development. In 2004 the U.S. Government proposed eventually replacing the Shuttle with a Crew Exploration Vehicle that would allow the agency to again send astronauts to the Moon. Despite the reduction of its budget following project Apollo, NASA has maintained a top-heavy bureaucracy resulting in inflated costs and compromised hardware. Crew Exploration Vehicle on October 31, 1998.]] Currently, the ISS relies on the Shuttle fleet for all major construction shipments. The Shuttle fleet has lost two spacecraft and fourteen astronauts in two disasters in 1986 and 2003. While the 1986 loss was made up with a Shuttle built from replacement parts, NASA does not plan to build another shuttle to replace the second loss. (But see also CEV.) The ISS, which was intended to have a crew of seven as of 2005, now has a skeleton crew of two, causing many intended research projects to be delayed. Other nations that have invested heavily in the space station's construction, such as the members of the European Space Agency, are fearful that the ISS's fate will soon match the fate of Skylab. As of 2005, however, all of the European and Japanese contributions to the ISS are years behind development schedule themselves.

NASA spaceflight missions

Human spaceflight


- Mercury program
- Gemini program
- Apollo program
- Skylab
- Space Shuttle
- International Space Station (working together with ESA, Rosviakosmos and JAXA)
- Project Constellation

Robotic space missions


- Earth Observing
  - Upper Atmosphere Research Satellite
  - TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)
- Lunar missions
  - Ranger
  - Surveyor
  - Lunar Orbiter
  - Clementine
  - Lunar Prospector
- Mercury missions
  - Mariner 10
  - MESSENGER
- Venus missions
  - Mariner 2, 5 and 10
  - Pioneer Venus
  - Magellan
- Mars missions
  - Mariner 4, 6, 7, 8 and 9
  - Viking 1 and 2
  - Mars Observer
  - Mars Pathfinder
  - Mars Climate Orbiter
  - Mars Polar Lander
  - Mars Global Surveyor
  - 2001 Mars Odyssey
  - Mars Exploration Rovers
  - Mars Reconnaissance Orbiter
  - Phoenix Lander (Planned for 2007)
  - Mars Science Laboratory (Planned for 2009)
- Jupiter missions
  - Pioneer 10
  - Galileo
  - Juno
- Saturn missions
  - Cassini-Huygens together with ESA
- Multi-planet missions
  - Pioneer 11 – Jupiter and Saturn
  - Mariner 10 – Venus and Mercury
  - Voyager 1 – Jupiter and Saturn
  - Voyager 2 – Jupiter, Saturn, Uranus and Neptune
  - New Horizons (Planned for 2006) – Jupiter, Pluto and Kuiper Belt
- Asteroidal/cometary missions
  - NEAR Shoemaker
  - Deep Space 1
  - Stardust
  - Deep Impact
  - Dawn (Planned for 2006)
- Proposed or canceled planetary-asteroid missions
  - JIMO (cancelled)
  - CRAF (cancelled)
  - NetLanders (cancelled)
  - Pluto Kuiper Express (cancelled; New Horizons is replacement)
  - Titan Explorer (proposed)
  - Neptune Orbiter (proposed)
- Sun observing missions
  - SOHO – ESA partnership
  - Ulysses – ESA partnership
- Great Observatories for Space Astrophysics
  - Hubble Space Telescope – ESA partnership
  - Compton Gamma Ray Observatory
  - Chandra X-ray Observatory
  - Spitzer Space Telescope (formerly known as the Space Infrared Telescope Facility, SIRTF)
- Other observatories
  - COBE
  - FUSE
  - Infrared Astronomical Satellite
  - James Webb Space Telescope – ESA partnership
  - WMAP

List of NASA administrators

# T. Keith Glennan (1958–1961) # James E. Webb (1961–1968) # Thomas O. Paine (1969–1970) # James C. Fletcher (1971–1977) # Robert A. Frosch (1977–1981) # James M. Beggs (1981–1985) # James C. Fletcher (1986–1989) # Richard H. Truly (1989–1992) # Daniel S. Goldin (1992–2001) # Sean O'Keefe (2001–2005) # Michael Griffin (2005–)

Field installations

In addition to headquarters in Washington, D.C., NASA has field installations at:
- Ames Research Center, Moffett Field, California
- Dryden Flight Research Center, Edwards, California
- John H. Glenn Research Center at Lewis Field, Cleveland, Ohio
- Goddard Space Flight Center, Greenbelt, Maryland
  - Goddard Institute for Space Studies, New York, New York
  - Independent Verification and Validation Facility, Fairmont, West Virginia
  - Wallops Flight Facility, Wallops Island, Virginia
- Jet Propulsion Laboratory, near Pasadena, California
  - Deep Space Network stations:
    - Goldstone Deep Space Communications Complex, Barstow, California
    - Madrid Deep Space Communication Complex, Madrid, Spain
    - Canberra Deep Space Communications Complex, Canberra, Australian Capital Territory
- Lyndon B. Johnson Space Center, Houston, Texas
  - White Sands Test Facility, Las Cruces, New Mexico
- John F. Kennedy Space Center, Florida
- Langley Research Center, Hampton, Virginia
- George C. Marshall Space Flight Center, Huntsville, Alabama
  - Michoud Assembly Facility, New Orleans, Louisiana
- John C. Stennis Space Center, Bay St. Louis, Mississippi

Awards and decorations

NASA presently bestows a number of medals and decorations to astronauts and other NASA personnel. Some awards are authorized for wear on active duty military uniforms. Current NASA awards are as follows:
- Congressional Space Medal of Honor
- NASA Distinguished Public Service Medal
- NASA Distinguished Service Medal
- NASA Equal Employment Opportunity Medal
- NASA Exceptional Achievement Medal
- NASA Exceptional Administrative Achievement Medal
- NASA Exceptional Bravery Medal
- NASA Exceptional Engineering Achievement Medal
- NASA Exceptional Scientific Achievement Medal
- NASA Exceptional Service Medal
- NASA Exceptional Technological Achievement Medal
- NASA Outstanding Leadership Medal
- NASA Public Service Medal
- NASA Space Flight Medal

Related legislation


- 1958 – National Aeronautics and Space Administration PL 85-568 (passed on July 29)
- 1961 – Apollo mission funding PL 87-98 A
- 1970 – National Aeronautics and Space Administration Research and Development Act PL 91-119
- 1984 – National Aeronautics and Space Administration Authorization Act PL 98-361
- 1988 – National Aeronautics and Space Administration Authorization Act PL 100-685
- NASA Budget 1958–2005 in 1996 Constant Year Dollars

See also


- List of aerospace engineering topics
- Astronaut
- Small Aircraft Transportation System
- Space Shuttle
- Space exploration
- Space race
- Robert Gilruth, Chris Kraft, Gene Kranz (flight directors)
- KC-135 Reduced Gravity Aircraft
- Shirley Thomas
- Stewart Brand
- Astronomy Picture of the Day
- Vision for Space Exploration
- Asteroid 11365 NASA is named after the organization.

Other space agencies


- Canadian Space Agency
- CNES (Centre National d'Études Spatiales)
- China National Space Administration
- European Space Agency
- Italian Space Agency
- Indian Space Research Organisation
- Japan Aerospace Exploration Agency
- National Space Agency of Ukraine
- Russian Federal Space Agency
- Soviet space program (historical)

External links

General


- [http://www.nasa.gov NASA Home Page]
- [http://www.nasawatch.com NASA Watch]
-

Further research


- [http://history.nasa.gov/series95.html NASA History Series Publications]
- [http://history.nasa.gov/SP-4012/cover.html NASA Historical Data Books (SP-4012)]
- [http://www.hq.nasa.gov/office/pao/History/hhrhist.pdf Research in NASA History: A Guide to the NASA History Program (large PDF – over 1,012 kb)]
- [http://ntrs.nasa.gov/ NTRS: NASA Technical Reports Server]
- [http://www.eventscope.org Eventscope] Category:Independent Agencies of the United States Government ko:미국항공우주국 ja:アメリカ航空宇宙局 simple:NASA th:องค์การนาซา

Mariner program

The Mariner program was a series of unmanned interplanetary probes designed to investigate Mars, Venus and Mercury. The program included a number of firsts, including the first planetary flyby, the first planetary orbiter, and the first gravity assist. Of the ten vehicles in the Mariner series, seven were successful and three were lost. The planned Mariner 11 and 12 vehicles evolved into Voyager 1 and Voyager 2 of the Voyager program.

Mariners 1 and 2

Mariner 1, intended to fly by Venus, failed shortly after launch. Mariner 2 was built as a backup to Mariner 1. It was launched on August 27, 1962, sending it on a 3½-month flight to Venus. The mission was a success and Mariner 2 became the first spacecraft to fly by another planet.
- Mission: Venus flyby
- Mass: 203 kg (446 lb)
- Sensors: microwave and infrared radiometers, cosmic dust, solar plasma and high-energy radiation, magnetic fields

Mariners 3 and 4

Mariner 3 and Mariner 4 were Mars flyby missions. Mariner 3 was lost when the launch vehicle's nose fairing failed to jettison. Its sister ship, Mariner 4, launched on November 28, 1964, the first successful flyby of the planet Mars and gave the first glimpse of Mars at close range.
- Mission: Mars flyby
- Mass: 261 kg (575 lb)
- Sensors: camera with digital tape recorder (about 20 pictures), cosmic dust, solar plasma, trapped radiation, cosmic rays, magnetic fields, radio occultation and celestial mechanics

Mariner 5

The Mariner 5 spacecraft was launched to Venus on June 14, 1967 and arrived in the vicinity of the planet in October 1967. It carried a complement of experiments to probe Venus' atmosphere with radio waves, scan its brightness in ultraviolet light, and sample the solar particles and magnetic field fluctuations above the planet.
- Mission: Venus flyby
- Mass: 245 kg (540 lb)
- Sensors: ultraviolet photometer, cosmic dust, solar plasma, trapped radiation, cosmic rays, magnetic fields, radio occultation and celestial mechanics

Mariners 6 and 7

Mariners 6 and 7 were identical teammates in a two-spacecraft mission to Mars. Mariner 6 was launched on February 24, 1969, followed by Mariner 7 on March 27, 1969. They flew over the equator and southern hemisphere of the planet Mars.
- Mission: Mars flybys
- Mass 413 kg (908 lb)
- Sensors: wide- and narrow-angle cameras with digital tape recorder, infrared spectrometer and radiometer, ultraviolet spectrometer, radio occultation and celestial mechanics.

Mariners 8 and 9

Mariner 8 and Mariner 9 were identical sister craft designed to map the Martian surface simultaneously, but Mariner 8 was lost in a launch vehicle failure. Its identical sister craft, Mariner 9, was launched in May 1971 and became the first artificial satellite of Mars. It entered Martian orbit in November 1971 and began photographing the surface and analyzing the atmosphere with its infrared and ultraviolet instruments.
- Mission: orbit Mars
- Mass 998 kg (2,200 lb)
- Sensors: wide- and narrow-angle cameras with digital tape recorder, infrared spectrometer and radiometer, ultraviolet spectrometer, radio occultation and celestial mechanics

Mariner 10

The Mariner 10 spacecraft launched on November 3, 1973 and was the first to use a gravity assist trajectory, accelerating as it entered the gravitational influence of Venus, then being flung by the planet's gravity onto a slightly different course to reach Mercury. It was also the first spacecraft to encounter two planets at close range, and the first (and so far only) spacecraft to photograph Mercury in closeup.
- Mission: Venus and Mercury flybys
- Mass: 433 kg (952 lb)
- Sensors: twin narrow-angle cameras with digital tape recorder, ultraviolet spectrometer, infrared radiometer, solar plasma, charged particles, magnetic fields, radio occultation and celestial mechanics Category:Mars missions Category:Mercury spacecraft Category:Venus spacecraft Category:NASA programs ja:マリナー計画

Ranger program

The Ranger program of unmanned space missions was the first United States attempt to obtain close-up images of the lunar surface. The Ranger spacecraft were designed to fly straight down towards the Moon and send images back until the moment of impact. Ranger was originally designed, beginning in 1959, in three distinct phases, called "blocks." Each block had different mission objectives and progressively more advanced system design. The JPL mission designers planned multiple launches in each block, to maximize the engineering experience and scientific value of the mission and to assure at least one successful flight. Total research, development, launch, and support costs for the Ranger series of spacecraft (Rangers 1 through 9) was approximately $170 million.

Block 1 missions

JPL Block 1, consisting of two spacecraft launched into Earth orbit in 1961, was intended to test the Atlas/Agena launch vehicle and spacecraft equipment without attempting to reach the Moon. Most elements of spacecraft technology taken for granted today were untested before Ranger. Perhaps the most important of these was three-axis attitude stabilization, meaning that the spacecraft is fixed in relation to space instead of being stabilized by spinning. This would permit pointing large solar panels at the Sun, a large antenna at Earth, and cameras and other directional scientific sensors at their appropriate targets. Rocket propulsion carried aboard the spacecraft was another critically important new technology, needed for accurate targeting at the Moon or distant planets. In addition, two-way communication and closed-loop tracking, requiring spacecraft and ground system development, and the use of on-board computing and sequencing combined with commands from the ground, all had to be developed and tried out in flight. Unfortunately, problems with the early version of the launch vehicle left Ranger 1 and Ranger 2 in short-lived, low-Earth orbits in which the spacecraft could not stabilize themselves, collect solar power, or survive for long.

Block 2 missions

Ranger 2 Block 2 of the Ranger project launched three spacecraft to the Moon in 1962, carrying a TV camera, a radiation detector, and a seismometer in a separate capsule slowed by a rocket motor and packaged to survive its low-speed impact on the Moon’s surface. The three missions together demonstrated good performance of the Atlas/Agena B launch vehicle and the adequacy of the spacecraft design, but unfortunately not all on the same attempt. Ranger 3 was launched into deep space, but an inaccuracy put it off course and it missed the Moon entirely. Ranger 4 had a perfect launch, but the spacecraft was completely disabled. The project team tracked the seismometer capsule to impact just out of sight on the lunar far side, validating the communications and navigation system. Ranger 5 missed the Moon and was disabled. No significant science information was gleaned from these missions. The craft weighed 331 kg.

Block 3 missions

Ranger's Block 3 embodied four launches in 1964-65. These spacecraft boasted a television instrument designed to observe the lunar surface during the approach; as the spacecraft neared the Moon, they would reveal detail smaller than the best Earth telescopes could show, and finally details down to dishpan size. The first of the new series, Ranger 6, had a flawless flight, except that the television system was disabled by an in-flight accident and could take no pictures. Ranger 6 The next three Rangers, with a redesigned television, were completely successful. Ranger 7 photographed its way down to target in a lunar plain, soon named Mare Cognitum, south of Copernicus crater. It sent more than 4,300 pictures from six cameras to waiting scientists and engineers. The new images revealed that craters caused by impact were the dominant features of the Moon's surface, even in the seemingly smooth and empty plains. Great craters were marked by small ones, and the small with tiny impact pockmarks, as far down in size as could be discerned -- about 50 centimeters (16 inches). The light-colored streaks radiating from Copernicus and a few other large craters turned out to be chains and nets of small craters and debris blasted out in the primary impacts. In February 1965, Ranger 8 swept an oblique course over the south of Oceanus Procellarum and Mare Nubium, to crash in Mare Tranquillitatis where Apollo 11 would land 4½ years later. It garnered more than 7,000 images, covering a wider area and reinforcing the conclusions from Ranger 7. About a month later, Ranger 9 came down in the 90 km diameter (75 mile) crater Alphonsus. Its 5,800 images, nested concentrically and taking advantage of very low-level sunlight, provided strong confirmation of the crater-on-crater, gently rolling contours of the lunar surface. Thus, after a long trouble-plagued start that taught the system engineers a great deal and the scientists virtually nothing, Project Ranger finished with three flights that greatly advanced the lunar scientists' knowledge of the surface and whetted their appetites for a closer look.

The Ranger spacecraft

Each Ranger spacecraft had 6 cameras on board. The cameras were fundamentally the same with differences in exposure times, fields of view, lenses, and scan rates. The camera system was divided into two channels, P (partial) and F (full). Each channel was self-contained with separate power supplies, timers, and transmitters. The F-channel had 2 cameras: the wide-angle A-camera and the narrow angle B-camera. The P-channel had four cameras: P1 and P2 (narrow angle) and P3 and P4 (wide angle). The final F-channel image was taken between 2.5 and 5 s before impact (altitude about 5 km) and the last P-channel image 0.2 to 0.4 s before impact (altitude about 600 m). The images provided better resolution than was available from Earth based views by a factor of 1000. Total research, development, launch, and support costs for the Ranger series of spacecraft (Rangers 1 through 9) was approximately $170 million.

Mission list


- Block 1
  - Ranger 1, launched 23 August 1961, lunar prototype, launch failure
  - Ranger 2, launched 18 November 1961, lunar prototype, launch failure
- Block 2
  - Ranger 3, launched 26 January 1962, lunar probe, spacecraft failed, missed moon
  - Ranger 4, launched 23 April 1962, lunar probe, spacecraft failed, impact
  - Ranger 5, launched 18 October 1962, lunar probe, spacecraft failed, missed
- Block 3
  - Ranger 6, launched 30 January 1964, lunar probe, impact, cameras failed
  - Ranger 7
    - Launched 28 July 1964
    - Impacted Moon 31 July 1964 at 13:25:49 UT
    - Latitude 10.35 S, Longitude 339.42 E - Mare Cognitum
  - Ranger 8
    - Launched 17 February 1965
    - Impacted Moon 20 February 1965 at 09:57:37 UT
    - Latitude 2.67 N, Longitude 24.65 E - Mare Tranquillitatis (Sea of Tranquility)
  - Ranger 9
    - Launched 21 March 1965
    - Impacted Moon 24 March 1965 at 14:08:20 UT
    - Latitude 12.83 S, Longitude 357.63 E - Alphonsus crater

External links


- [http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19780007206_1978007206.pdf Lunar Impact: A History of Project Ranger (PDF) 1977]
- [http://history.nasa.gov/SP-4210/pages/Cover.htm Lunar Impact: A History of Project Ranger (HTML)] Both links lead to a whole book on the program. For the HTML one, scroll down to see the table of contents link.

See also


- Surveyor program
- Lunar Orbiter program
- Apollo program
- Luna programme
- [http://wikisource.org/wiki/NASA_FACTS_Volume_2_number_6_PROJECT_RANGER NASA_FACTS_Volume_2_number_6_PROJECT_RANGER on wikisource]
-

Infrared

Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of microwave radiation. The name means "below red" (from the Latin infra, "below"), red being the color of visible light of longest wavelength. Infrared radiation spans three orders of magnitude and has wavelengths between 700 nm and 1 mm.

Different regions in the infrared

IR is often subdivided into:
- near infrared NIR, IR-A DIN, 0.7–1.4 µm in wavelength, defined by the water absorption, and commonly used in fiber optic telecommunication because of low attenuation losses in the SiO2 glass (silica) medium.
- short wavelength IR SWIR, IR-B DIN, 1.4–3 µm, water absorption increases significantly at 1450 nm
- mid wavelength IR MWIR, IR-C DIN, also intermediate-IR (IIR), 3–8 µm
- long wavelength IR LWIR, IR-C DIN, 8–15 µm)
- far infrared FIR, 15–1000 µm However, these terms are not precise, and are used differently in various studies i.e. near (0.7–5 µm) / mid (5–30 µm) / long (30–1000 µm). Especially at the telecom-wavelengths the spectrum is further subdivided into individual bands, due to limitations of detectors, amplifiers and sources. Infrared radiation is often linked to heat, since objects at room temperature or above will emit radiation mostly concentrated in the mid-infrared band (see black body). black body The common nomenclature is justified by the different human response to this radiation (near infrared = the red you just cannot see, far IR = thermal radiation), other definitions follow different physical mechanisms (emission peaks, vs. bands, water absorption) and the newest follow technical reasons (The common silicon detectors are sensitive to about 1050 nm, while InGaAs sensitivity starts around 950 nm and ends between 1700 and 2200 nm, depending on the specific configuration). Unfortunately the international standards for these specifications are not currently available.

Telecommunication bands in the infrared

Optical telecommunication in the near infrared is technically often separated to different frequency bands because of availability of light sources, transmitting /absorbing materials (fibers) and detectors.
- O-band 1260–1360 nm
- E-band 1360–1460 nm
- S-band 1460–1530 nm
- C-band 1530–1565 nm
- L-band 1565–1625 nm
- U-band 1625–1675 nm

The Earth as an infrared emitter

The Earth's surface absorbs visible radiation from the sun and re-emits much of the energy as infrared back to the atmosphere. Certain gases in the atmosphere, chiefly water vapor, but also carbon dioxide, methane, nitrous oxide, sulfur hexafluoride, and chlorofluorocarbons, absorb this infrared, and re-radiate it in all directions including back to Earth. Thus, the greenhouse effect, keeps the atmosphere and surface much warmer than if the infrared absorbers were absent from the atmosphere.

Applications

Night vision

Infrared is used in night-vision equipment, when there is insufficient visible light to see an object. The radiation is detected and turned into an image on a screen, hotter objects showing up brighter, enabling the police and military to acquire thermally significant targets, such as human beings and automobiles. Also see Forward looking infrared. Smoke is more transparent to infrared than to visible light, so firefighters use infrared imaging equipment when working in smoke-filled areas.

Other imaging

In infrared photography, infrared filters are used to capture only the infrared spectrum. Digital cameras often use infrared blockers. Cheaper digital cameras and some camera phones which do not have appropriate filters can "see" infrared, appearing as a bright white colour (try pointing a TV remote at your digital camera). This is especially pronounced when taking pictures of subjects near bright areas (such as near a lamp), where the resulting infrared interference can wash out the image.

Thermography

Infrared radiation can be used to remotely determine the temperature of objects (if the emissivity is known). This is termed thermography, or in the case of very hot objects in the NIR or visible it is termed pyrometry. Thermography (thermal imaging) is mainly used in military and industrial applications but the technology is reaching the public market in the form of infrared cameras on cars due to the massively reduced production costs.

Heating

Infrared radiation is used in Infrared saunas to heat the sauna's occupants and to remove ice from the wings of aircraft (de-icing).

Communications

IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants. These devices usually conform to standards published by IrDA, the Infrared Data Association. Remote controls and IrDA devices use infrared light-emitting diodes (LEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beam is modulated, i.e. switched on and off, to encode the data. The receiver uses a silicon photodiode to convert the infrared radiation to an electric current. It responds only to the rapidly pulsing signal created by the transmitter, and filters out slowly changing infrared radiation from ambient light. Infrared communications are useful for indoor use in areas of high population density. IR does not penetrate walls and so does not interfere with other devices in adjoining rooms. Free space optical communication using infrared lasers can be a relatively inexpensive way to install a Gigabit/s communications link in urban areas, compared to the cost of burying fibre optic cable. Infrared lasers are used to provide the light for optical fibre communications systems. Infrared light with a wavelength around 1330 nm (best transmission) or 1550 nm (least dispersion) are the best choices for standard silica fibres.

Spectroscopy

Infrared radiation spectroscopy is the study of the composition of (usually) organic compounds, finding out a compound's structure and composition based on the percentage transmittance of IR radiation through a sample. Different frequencies are absorbed by different stretches and bends in the molecular bonds occurring inside the sample. Carbon dioxide, for example, has a strong absorption band at 4.2µm.

History

The discovery of infrared radiation is commonly ascribed to William Herschel, the astronomer, in the early 19th century. Herschel used a prism to refract light from the sun and detected the infrared, beyond the red part of the spectrum, through an increase in the temperature recorded on a thermometer. Simple infrared sensors were used by British, American and German forces in the Second World War as night vision aids for snipers.

See also


- Night vision
- Infrared astronomy
- Infrared photography
- Infrared spectroscopy
- Thermography
- Infrared homing

External links

Journals


- [http://www.sciencedirect.com/science/journal/13504495 Infrared Physics and Technology] (Elsevier) (last access June 2005).

Web sites


- [http://scienceofspectroscopy.info/wiki/index.php?title=Infrared_Spectroscopy Infrared Spectroscopy] NASA Open Spectrum wiki site.
- [http://www.irda.org/ IrDA]Organization that creates low cost infrared data interconnection standards. Category:Electromagnetic spectrum ja:赤外線

Micrometeorite

A Micrometeoroid (also micrometeorite, micrometeor) is a tiny meteoroid; a small particle of rock from space, usually weighing less than a gram, that poses a threat to space exploration. The risk is especially high for objects in space for long periods of time, such as satellites. They also pose major engineering challenges in theoretical low-cost lift systems such as rotavators, space elevators, and orbital airships. Micrometeoroids are extremely common in space, particularly near the Earth. Their velocities relative to a spacecraft in orbit can be on the order of kilometers per second, and resistance to micrometeoroid impact is a significant design challenge for spacecraft designers. Micrometeoroids are typically small, typically metallic, pieces of rock broken off from larger chunks of rock and debris. They typically date back to the formation of the solar system. Since orbital velocities are so high, and since they can enter an earth orbit from any angle, micrometeoroids in earth orbit constantly intercept the orbits of spacecraft and impact them at high speed. While their tiny size limits the damage incurred, the high velocity constantly degrades the outer casing of spacecraft and, in the long term, can threaten the functionality of systems. Micrometeoroids can also be easily found on earth in places where rainwater can concentrate them (such as a drain spout of roof gutters). Since metallic dust occurs relatively rarely on earth from other sources, metallic micrometeoroids can typically be separated from Earth dust via a strong magnet. Micrometeoroids comprise most of the 30,000 tons of space debris that are deposited on Earth every year. Impacts by small objects with extremely high velocity are a current area of research in terminal ballistics. Accelerating objects up to such velocities is difficult; current techniques include linear motors and shaped charges. In order to understand the micrometeoroid population better, a number of spacecraft (including Lunar Orbiter 1, Luna 3 and Mars 1) include micrometeoroid detectors. Category:Meteoroids

Magnetometer

A magnetometer is a scientific instrument used to measure the strength of magnetic fields. A magnetograph is a magnetometer that continuously records data. Earth's magnetism varies from place to place and differences in the Earth's magnetic field (the magnetosphere) can be caused by a couple of things: #The differing nature of rocks #The interaction between charged particles from the sun and the magnetosphere Magnetometers are used in geophysical surveys to find deposits of iron because they can measure the magnetic pull of iron. Magnetometers are also used to detect archeological sites, shipwrecks and other buried or submerged objects. A magnetometer can also be used by satellites like GOES to measure both the magnitude and direction of the earth's magnetic field. Magnetometers are very sensitive, and can give an indication of possible auroral activity before one can even see the light from the aurora. Magnetometers can be divided into two basic types:
- scalar magnetometers, that measure the total strength of the magnetic field to which they are subjected, and
- vector magnetometers, that have the capability to measure the component of the magnetic field in a particular direction. The use of three orthogonal vector magnetometers allows the magnetic field strength, inclination and declination to be uniquely defined. Examples of vector magnetometers are fluxgates and superconducting quantum interference devices, or SQUIDs. Some scalar magnetometers are discussed below.

Proton precession magnetometer

One type of magnetometer is the proton precession magnetometer, which operates on the principle that protons are spinning on an axis aligned with the magnetic field. An inductor creates a strong magnetic field around a hydrogen-rich fluid, causing the protons to align themselves with the newly created field. The field is then interrupted, and as protons are realigned with Earth's magnetic field, spinning protons precess at a specific frequency. This produces a weak magnetic field that is picked up by the same inductor. The relationship between the frequency of the induced current and the strength of Earth's magnetic field is called the proton gyromagnetic ratio, and is equal to 0.042576 hertz per nanotesla (Hz/nT).

Overhauser magnetometer

The Overhauser effect takes advantage of a quantum physics effect that applies to the hydrogen atom. This effect occurs when a special liquid (containing free, unpaired electrons) is combined with hydrogen atoms and then exposed to secondary polarization from a radio frequency (RF) magnetic field (i.e. generated from a RF source). RF magnetic fields are ideal for use in magnetic devices because they are transparent to the Earth's DC magnetic field and the RF frequency is well out of the bandwidth of the precession signal (i.e. they do not contribute noise to the measuring system). The unbound electrons in the special liquid transfer their excited state (i.e. energy) to the hydrogen nuclei (i.e. protons). This transfer of energy alters the spin state populations of the protons and polarizes the liquid – just like a proton precession magnetometer – but with much less power and to much greater extent. The proportionality of the precession frequency and magnetic flux density is perfectly linear, independent of temperature and only slightly affected by shielding effects of hydrogen orbital electrons. The constant of proportionality is known to a high degree of accuracy and is identical to the proton precession gyromagnetic constant. Overhauser magnetometers achieve some 0.01 nT/Hz1/2 noise levels, depending on particulars of design, and they can operate in either pulsed or continuous mode.

Caesium vapour magnetometer

A basic example of the workings of a magnetometer may be given by discussing the common "Optically pumped caesium vapour magnetometer" which is a sensitive and accurate device used across a wide range of fields. Although it relies on some interesting quantum mechanics to operate, its basic principles are easily explained. The device broadly consists of three items: a photon emitter containing a caesium emitter, a chamber containing caesium vapour, and a 'buffer gas' through which the emitted photons and a photon detector, arranged in that order.

Calibration

The basic principle that allows the device to operate is the fact that a caesium atom can exist in any of six energy levels (the placement of electron 'orbits' around the atomic nucleus). When a caesium atom within the chamber encounters a photon from the emitter, it jumps to a higher energy state and then re-emits a photon and falls to an indeterminate lower energy state. The caesium atom is only 'sensitive' to the photons from the emitter in three of its six energy states, and therefore eventually (assuming a closed system) all the atoms will fall into a state in which the all the photons from the emitter will pass through unhindered and be measured by the photon detector. At this stage the device can be said to be perfectly calibrated.

Detection

Given that our theoretical magnetometer is now calibrated we can expose it to the environment. It is easy to imagine that the environment is constantly emitting quanta of energy and that some of these will pass through our chamber. When they do, they may hit one of our caesium atoms and cause it to jump into a new energy state, which may in turn be one in which it can absorb a photon from out caesium emitter. If this is the case it will cause a decrease in the number of photons reaching our detector and this can be easily recorded. Scaling from this simple example to account for the vast number of energy transactions occurring within the caesium vapour, it is easy to see how the system works.

Real World

Obviously, when removed from an isolated environment, the caesium vapour can never be 'perfectly' calibrated and the system is subject to much environmental interference. However, by the application of feedback systems and an averaging of the detection rates seen in a benign environment, we can calibrate the instrument sufficiently well in a real-world environment to make it accurate and useful for detecion.

Early magnetometers

In 1833 Carl Friedrich Gauss, head of the Geomagnetic Observatory in Gottingen, published a paper entitled "On the intensity of the Earth's magnetic field expressed in absolute measure". It described a new instrument that Gauss called a "magnometer" (a term which is still occasionally used instead of magnetometer) [http://www.ee.vt.edu/~museum/time/time3.html]. It consisted of a permanent bar magnet suspended horizontally from a gold fibre [http://www.ctsystems.org/gauss.htm]. A magnetometer is also called a gaussmeter.

External links


- [http://www.portup.com/~dfount/proton.htm Dan's Homegrown Proton Precession Magnetometer Page]
- [http://geomag.usgs.gov USGS Geomagnetism Program]
- [http://www.archaeologicalprospectors.com Archaeological Prospectors]

Mariner 1

Mariner 1 was the first spacecraft of the Mariner program. Intended to fly by Venus, it failed during launch on July 22, 1962. A hardware failure in an antenna caused the booster to lose contact with guidance systems on the ground, so an onboard computer assumed control. However, that computer's software contained a bug. The error had occurred when an equation was being transcribed by hand in the specification for the guidance program. The writer missed the superscript bar in \bar\dot_n (the nth smoothed value of the time derivative of a radius). Without the smoothing function indicated by the bar, the program treated normal minor variations of velocity as if they were serious, causing spurious corrections that sent the rocket off course. It was then destroyed by the range safety officer. (It is sometimes claimed that the bug consisted a period typed in place of a comma, causing a FORTRAN statement of the form "DO 17 I = 1, 10" to be interpreted as "DO17I = 1.10" (an assignment to a variable called DO17I), since space characters are not significant in that language. There was in fact such a bug in a NASA orbit computation program at about this time, but it was a program for Project Mercury, not Mariner, and this bug was discovered before serious consequences occurred.) The probe's mission was later completed by Mariner 2.

Detailed Description

This was to be the first Mariner mission. It was intended to perform a Venus flyby. The vehicle was destroyed by the Range Safety Officer 293 seconds after launch at 09:26:16 UT when it veered off course. The booster had performed satisfactorily until an unscheduled yaw-lift (northeast) maneuver was detected by the range safety officer. Faulty application of the guidance commands made steering impossible and were directing the spacecraft towards a crash, possibly in the North Atlantic shipping lanes or in an inhabited area. The destruct command was sent 6 seconds before separation, after which the launch vehicle could not have been destroyed. The radio transponder continued to transmit signals for 64 seconds after the destruct command had been sent. The failure was apparently caused by a combination of two factors. Improper operation of the Atlas airborne beacon equipment resulted in a loss of the rate signal from the vehicle for a prolonged period. The airborne beacon used for obtaining rate data was inoperative for four periods ranging from 1.5 to 61 seconds in duration. Additionally, the Mariner 1 Post Flight Review Board determined that the omission of a hyphen in coded computer instructions in the data-editing program allowed transmission of incorrect guidance signals to the spacecraft. During the periods the airborne beacon was inoperative the omission of the hyphen in the data-editing program caused the computer to incorrectly accept the sweep frequency of the ground receiver as it sought the vehicle beacon signal and combined this data with the tracking data sent to the remaining guidance computation. This caused the computer to swing automatically into a series of unnecessary course corrections with erroneous steering commands which finally threw the spacecraft off course.

Spacecraft and Subsystems

The Mariner 1 spacecraft was identical to Mariner 2, launched 27 August 1962. Mariner 1 consisted of a hexagonal base, 1.04 meters across and 0.36 meters thick, which contained six magnesium chassis housing the electronics for the science experiments, communications, data encoding, computing, timing, and attitude control, and the power control, battery, and battery charger, as well as the attitude control gas bottles and the rocket engine. On top of the base was a tall pyramid-shaped mast on which the science experiments were mounted which brought the total height of the spacecraft to 3.66 meters. Attached to either side of the base were rectangular solar panel wings with a total span of 5.05 meters and width of 0.76 meters. Attached by an arm to one side of the base and extending below the spacecraft was a large directional dish antenna. The Mariner 1 power system consisted of the two solar cell wings, one 183 cm by 76 cm and the other 152 cm by 76 cm (with a 31 cm dacron extension (a solar sail) to balance the solar pressure on the panels) which powered the craft directly or recharged a 1000 Watt-hour sealed silver-zinc cell battery, which was to be used before the panels were deployed, when the panels were not illuminated by the Sun, and when loads were heavy. A power-switching and booster regulator device controlled the power flow. Communications consisted of a 3 Watt transmitter capable of continuous telemetry operation, the large high gain directional dish antenna, a cylindrical omnidirectional antenna at the top of the instrument mast, and two command antennas, one on the end of either solar panel, which received instructions for midcourse maneuvers and other functions. Propulsion for midcourse maneuvers was supplied by a monopropellant (anhydrous hydrazine) 225 N retro-rocket. The hydrazine was ignited using nitrogen tetroxide and aluminum oxide pellets, and thrust direction was controlled by four jet vanes situated below the thrust chamber. Attitude control with a 1 degree pointing error was maintained by a system of nitrogen gas jets. The Sun and Earth were used as references for attitude stabilization. Overall timing and control was performed by a digital Central Computer and Sequencer. Thermal control was achieved through the use of passive reflecting and absorbing surfaces, thermal shields, and movable louvers. The scientific experiments were mounted on the instrument mast and base. A magnetometer was attached to the top of the mast below the omnidirectional antenna. Particle detectors were mounted halfway up the mast, along with the cosmic ray detector. A cosmic dust detector and solar plasma spectrometer detector were attached to the top edges of the spacecraft base. A microwave radiometer and an infrared radiometer and the radiometer reference horns were rigidly mounted to a 48 cm diameter parabolic radiometer antenna mounted near the bottom of the mast. Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.

See also


- RISKS Digest [http://catless.ncl.ac.uk/Risks/8.75.html#subj1 detail about the Mariner I failure] Category:Venus spacecraft Category:Mariner program

July 22

22 July is the 203rd day (204th in leap years) of the year in the Gregorian Calendar, with 162 days remaining.

Events


- 1298 - Battle of Falkirk - Edward I (Longshanks) of England and his longbowmen defeat William Wallace and his scottish schiltrons outside the town.
- 1499 - Battle of Dornach - The Swiss decisively defeat the Imperial army of Emperor Maximilian I.
- 1587 - Colony of Roanoke: A second group of English settlers arrive on Roanoke Island off of North Carolina to re-establish the deserted colony.
- 1793 - Alexander Mackenzie reaches the Pacific Ocean becoming the first Euro-American to complete a transcontinental crossing north of Mexico.
- 1796 - Surveyors of the Connecticut Land Company name an area in Ohio "Cleveland" after Gen. Moses Cleaveland, the superintendent of the surveying party.
- 1805 - Napoleonic Wars: War of the Third Coalition - inconclusive battle of Cape Finisterre fought between a combined French and Spanish fleets under Admiral Pierre-Charles Villeneuve of Spain and a British fleet under Admiral Robert Calder.
- 1812 - Napoleonic Wars: Peninsular War - Battle of Salamanca - British forces led by Arthur Wellesley (later the Duke of Wellington) defeat French troops near Salamanca, Spain.
- 1864 - American Civil War: Battle of Atlanta - Outside of Atlanta, Georgia, Confederate General John Bell Hood leads an unsuccessful attack on Union troops under General William T. Sherman on Bald Hill.
- 1908 - Albert Fisher establishes the Fisher Body Company to manufacture carriage and automobile bodies.
- 1916 - In San Francisco, California, a bomb explodes on Market Street during a Preparedness Day parade killing 10 and injuring 40.
- 1933 - Wiley Post becomes first person to fly solo around the world traveling 15,596 miles in 7 days, 18 hours and 45 minutes.
- 1934 - Outside Chicago's Biograph Theatre, "Public Enemy No. 1" John Dillinger is mortally wounded by FBI agents.
- 1937 - New Deal: The United States Senate votes down President Franklin D. Roosevelt's proposal to add more justices to the Supreme Court of the United States.
- 1942 - The United States government begins compulsory civilian gasoline rationing due to the wartime demands.
- 1942 - Holocaust: The systematic deportation of Jews from the Warsaw Ghetto begins.
- 1943 - Allied forces capture the Italian city of Palermo.
- 1944 - The Polish Committee of National Liberation publishes its manifesto, starting the period of Communist rule in Poland
- 1946 - King David Hotel bombing: Irgun bombs King David Hotel in Jerusalem, headquarters of the British civil and military administration, killing 90.
- 1962 - Mariner program: Mariner 1 spacecraft flies erratically several minutes after launch and has to be destroyed.
- 1977 - Chinese leader Deng Xiaoping is restored to power.
- 1991 - Serial killer Jeffrey Dahmer is arrested after the remains of 11 men and boys are found in his Milwaukee apartment.
- 1992 - Near Medellín, Colombian drug lord Pablo Escobar escapes from his luxury prison fearing extradition to the United States.
- 1997 - The second Blue Water Bridge opens between Port Huron, Michigan and Sarnia, Ontario.
- 2002 - Israel assasinates Salah Shahade, the Commander-in-Chief of Hamas's military arm, Ezzedeen-al-qassam Brigades, along with 14 civilians.
- 2003 - Members of 101st Airborne of the United States, aided by Special Forces, attack a compound in Iraq, killing Saddam Hussein's sons Uday and Qusay, along with Mustapha Hussein, Qusay's 14-year old son, and a bodyguard.
- 2005 - A man is shot dead by police as the hunt begins for the London Bombers. See 7 July 2005 London bombings and 21 July 2005 London bombings
- 2005 - Microsoft releases the final name for its next-gen operating system, Longhorn. The name will be "Windows Vista".

Births


- 1210 - Joan of England, queen of Alexander II of Scotland (d. 1238)
- 1478 - King Philip I of Castile (d. 1506)
- 1510 - Alessandro de' Medici, Duke of Florence (d. 1537)
- 1519 - Pope Innocent IX (d. 1591)
- 1535 - Katarina Stenbock, queen of Gustav I of Sweden (d. 1621)
- 1559 - Lawrence of Brindisi, Italian monk (d. 1619)
- 1621 - Anthony Ashley-Cooper, 1st Earl of Shaftesbury, English politician (d. 1683)
- 1711 - Georg Wilhelm Richmann, Russian physicist (d. 1753)
- 1713 - Jacques-Germain Soufflot, French architect (d. 1780)
- 1733 - Mikhail Shcherbatov, Russian philosopher and writer (d. 1790)
- 1784 - Friedrich Bessel, German mathematician and astronomer (d. 1846)
- 1822 - Gregor Mendel, Austrian geneticist (d. 1884)
- 1844 - William Archibald Spooner, English priest and scholar (d. 1930)
- 1859 - Emma Lazarus, American poet (d. 1887)
- 1882 - Edward Hopper, American painter (d. 1967)
- 1887 - Gustav Ludwig Hertz, German physicist, Nobel Prize laureate (d. 1975)
- 1888 - Selman Waksman, Ukrainian-born biochemist, recipient of the Nobel Prize in Physiology or Medicine (d. 1973)
- 1893 - James Whale, English film director (d. 1957)
- 1898 - Stephen Vincent Benét, American author (d. 1943)
- 1898 - Alexander Calder, American artist (d. 1976)
- 1905 - Doc Cramer, baseball player (d. 1990)
- 1908 - Amy Vanderbilt, American author on etiquette (d. 1974)
- 1913 - Gorni Kramer, Italian bandleader and songwriter
- 1916 - Marcel Cerdan, French boxer (d. 1949)
- 1921 - William Roth, U.S. Senator (d. 2003)
- 1923 - Bob Dole, U.S. Senator from Kansas and Presidential candidate
- 1923 - Mukesh, Indian singer (d. 1976)
- 1924 - Margaret Whiting, singer
- 1928 - Orson Bean, American film actor
- 1932 - Oscar De la Renta, Dominican-born fashion designer
- 1934 - Louise Fletcher, American actress
- 1936 - Tom Robbins, American author
- 1939 - Terence Stamp, English actor
- 1940 - Alex Trebek, Canadian-born game show host
- 1941 - George Clinton, American musician
- 1941 - Ron Turcotte, Canadian jockey
- 1943 - Kay Bailey Hutchison, U.S. Senator from Texas
- 1944 - Estelle Bennett, American singer (Ronettes)
- 1944 - Rick Davies, British musician (Supertramp)
- 1944 - Sparky Lyle, baseball player
- 1946 - Mireille Mathieu, French singer
- 1946 - Stephen M. Wolownik, Russian musician (d. 2000)
- 1947 - Albert Brooks, American comedian
- 1947 - Danny Glover, American actor
- 1947 - Don Henley, American drummer, singer, and songwriter (Eagles)
- 1948 - S.E. Hinton, American author
- 1948 - Otto Waalkes, German comedian
- 1949 - Alan Menken, American composer
- 1949 - Lasse Virén, Finnish athlete
- 1954 - Lonette McKee, American actress
- 1954 - Al Di Meola, American guitarist
- 1955 - Willem Dafoe, American actor
- 1961 - Keith Sweat, American singer
- 1964 - Patrick Labyorteaux, American actor
- 1964 - John Leguizamo, Colombian actor
- 1964 - David Spade, American actor, comedian, and producer
- 1965 - Shawn Michaels, American professional wrestler
- 1966 - Tim Brown, American football player
- 1971 - Kristine Lilly, American soccer player
- 1972 - Keyshawn Johnson, American football playe