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Space Organizations Part 1: NASA - Nasa's Robotic Space Programs

spacecraft earth mars missions

Although NASA's crewed missions have historically received the most public attention, the agency has sent a number of unmanned (robotic) spacecraft into outer space. These machines have taken a number of forms and achieved some incredible milestones in space exploration. Satellites have been put into Earth orbit since the earliest days of NASA's space program to collect weather data or serve military purposes. During the 1960s and 1970s lunar probes were sent to the Moon to support the Apollo program. At the same time, NASA began launching robotic explorers that traveled to other planets. These were followed by sophisticated observatories and other robotic spacecraft placed in orbit around the Earth or Sun or sent to intercept asteroids. These projects are considered crucial to enhancing human understanding of the workings of the Earth, the surrounding solar system, and the universe at large.

Interplanetary Explorers

NASA has conducted a number of interplanetary robotic missions to further space science. The Mariner program began in 1962 and included ten spacecraft sent to gather data as they flew by Mercury, Venus, or Mars. In December 1962 Mariner 2 became the first spacecraft to fly by another planet when it flew within 22,000 miles of Venus. In 1971 Mariner 9 became Mars's first artificial satellite. It sent back more than 7,000 photos of the Red Planet.

The Mariner program provided valuable information that was used during the 1970s to conduct the Viking program. In 1976 twin Viking spacecraft were placed in Martian orbit and sent landers down to the planet's surface. On July 20, 1976, the Viking 1 lander set down on Mars. It was the first safe landing of a spacecraft on another planet. The next year Voyager 1 and Voyager 2 were launched toward the far planets in the solar system. They journeyed past Jupiter and Saturn and continued outward. Voyager 2 flew by Uranus and Neptune. By 1998 Voyager 1 had traveled farther than any human-made object in history. As of February 2004 both Voyagers were still moving toward the outer boundaries of the solar system. NASA hopes it can maintain contact with them as they enter the new frontier of interstellar space.

In 1989 NASA launched two interplanetary missions: Magellan to Venus and Galileo to Jupiter. In August 1990 the Magellan lander set down on the Venutian surface. Five years later Galileo began orbiting Jupiter. It continued to send NASA data until September 2003. Both missions provided new maps of planetary surfaces and important atmospheric data.

The 1990s were a tough decade for NASA's interplanetary craft. Three spacecraft sent to Mars were lost: the Mars Observer in 1992, the Mars Climate Orbiter in 1998, and the Mars Polar Lander/Deep Space 2 of 1999. However, in 1997 the Mars Global Surveyor was put into Martian orbit. The same year Mars Pathfinder successfully put a lander, including the Sojourner rover, on the Martian surface. It explored an area called Ares Vallis in the planet's northern hemisphere.

During the early 2000s NASA had great success with interplanetary missions. In late 2001 Mars Odyssey arrived in Martian orbit and began mapping the planet. Two years later the Mars Exploration mission was launched including twin landing craft with rovers named Spirit and Opportunity. In January 2004 the rovers landed safely on Mars and began exploring its terrain.

In late June 2004 the Cassini spacecraft reached Saturn. It was launched in 1997 as a joint mission between NASA, the European Space Agency (ESA), and the Italian space agency. This robotic spacecraft will orbit the planet for four years and release a scientific probe called Huygens into the atmosphere of Saturn's largest moon, Titan.

Earth and Sun Orbiters

NASA's space science program has been launching robotic spacecraft into orbit since the 1960s. These spacecraft have included numerous satellites put into Earth orbit to collect data about the planet's weather, oceans, and atmosphere. Other NASA satellites were designed to look outward into space.

During the 1980s the agency began a program called NASA's Great Observatories. There are four robotic spacecraft in this program: the Hubble Space Telescope (launched in April 1990), the Compton Gamma Ray Observatory (launched in April 1991), the Chandra X-Ray Observatory (launched in July 1999), and the Spitzer Space Telescope (launched in August 2003). These Earth-orbiting spacecraft contain highly advanced and sensitive instruments that allow scientists to study radiation emitted from nearby celestial bodies and distant galaxies. The space observatories provide a clear picture of the universe because they are located outside the interference of Earth's atmosphere.

Throughout its history NASA has operated a number of small observatories and satellites that incorporate sophisticated instruments such as scatterometers (a specialized form of radar for Earth study) and interferometers (for precise determinations of distance or wavelengths in space).

Numerous NASA science programs are geared toward studying the flow of energy from the Sun to the Earth. This energy includes a continuous flow of plasma called the solar wind. The solar wind and other emissions from the sun affect the magnetic properties of the space surrounding the Earth (or geospace). This magnetic phenomenon is known as "space weather."

During the 1990s NASA began the Discovery program. The goal of this program is to carry out numerous, relatively small and inexpensive space missions with specific objectives. Each mission must cost less than $299 million and proceed from initial development to launch within thirty-six months. NASA calls Discovery the "faster, better, cheaper" approach to space science. Discovery missions ongoing as of February 2004 have a number of goals, including investigation of comets, asteroids, and space weather.

The Explorers program is another NASA science program dedicated to operating small-to-medium sized space missions for a modest cost (less than $180 million per mission). This program includes satellites and observatories that gather data about the Earth, the Sun, and the surrounding universe.

NASA also works with international partners to perform space science missions. The International Solar-Terrestrial Physics (ISTP) Science Initiative is a collaborative effort between NASA, ESA, and Japan's space agency. Begun in the 1990s the ISTP program uses satellites to gather information about space weather and its affects on geospace (the space around the Earth). Ulysses is a joint NASA-ESA mission to study the Sun. The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is an observatory operated by the ESA in conjunction with NASA and the Russian space agency.

Space Organizations Part 1: NASA - Nasa's Organization And Facilities [next] [back] Space Organizations Part 1: NASA - The International Space Station

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