Interplanetary Probes

The Cassini-Huygens probe courtesy of Jet Propulsion Labs

Introduction

The purpose of probes is to help us solve the mysteries of the solar system. There have been many interplanetary probes launched primarily by the Russian Space Agency and NASA but also some from the European and Japanese Space Agencies. At first probes were mainly sent to the Moon, but now they have been sent to explore the far reaches of the solar system. Some probes have been sent merely to hit the planet, whilst others were sent to explore the atmosphere of the planet. This section will look at probes to the different planets.

Lunar Probes

Luna (1959 - 1976)

Luna was a series of 24 lunar probes launched by the former USSR. 11 were successful and achievements of the series were great: The first man made object to reach another planetary body (Luna 2, 1959). The first pictures sent back of the far side of the Moon (Luna 3, 1959). The first probe to soft land on another planetary body (Luna 9, 1966). The first probe to orbit another planetary body (Luna 10, 1966). The first soil return to Earth from another planetary body (Luna 16, 1970). The first Lunar rover Lunokhod (unmanned) (Luna 17, 1970). To the right is a picture of Luna 9.

Pioneer (1958-59)

Pioneer was a series of five US lunar flights between 1958 and 1959, but only 4 was successful. 4 was launched on March 3, 1959. It achieved an Earth-Moon trajectory, passing within 37,000 miles of the Moon before falling into a solar orbit.

Ranger (1961-65)

The US Ranger series was designed to fly straight to the Moon and send back images of the surface of the Moon before impact. It was the first US attempt to obtain images of the surface of the Moon using a probe. To the left is the Ranger spacecraft. Ranger 7 impacted in the mare terrain modified by crater rays. Ranger 8 also impacted in the mare terrain, but in an area of complex system of ridges. Ranger 9 impacted in the lunar highlands. The images sent back showed the planners of the Apollo missions that finding a smooth landing place would not be easy since the surface if the Moon is made up of so many craters and ridges.

Zond (1965-70)

Zond was a series of 8 lunar probes launched by the former USSR, 5 of which were successful. Some were tests for future Mars and Soyuz missions.

Surveyor (1966-68)

Surveyor probes were the first U.S. spacecraft to land safely on the Moon's surface. They were designed to obtain close-up images of the lunar surface and thus allowing project leaders to determine if a manned landing would be possible. Each probe had a television camera, but in addition Surveyors 3 and 7 each carried a soil sampler scoop which dug trenches and was used for soil testing. Surveyors 5, 6 and 7 had magnets attached to the footpads and an alpha scattering instrument for chemical analysis of the lunar material. Surveyors 1,2 and 4 were lost before they could complete their missions.

Lunar Orbiter (1966-67)

There were five US Lunar Orbiter missions designed to map the lunar surface. All the missions were successful and they mapped 99% of the Moon. The first three missions were dedicated to imaging potential lunar landing sites, which had been selected based on Earth-based observations. The fourth and fifth missions were used to image the lunar surface for more scientific purposes. Right, is an image taken by the Lunar Orbiter 4 of the Moon centred on the Mare Orientale Basin. The innermost circle of the "bull's eye" is the Cordillera Mountain scarp, almost 900km in diameter.

Hiten-Hagomoro (1990-1993)

This was the first Japanese lunar orbiter, and the first ever craft to successfully complete an aerobraking manoeuvre. It completed 10 flybys of the moon before being deliberately crashed.

Lunar Prospector (1998-1999)

Lunar Prospector was sent particularly to further investigate the potential signs of water ice that had been discovered by the probe Clementine. It found signs that the moon had a tiny iron-rich core, but upon descent to the surface after its orbital mission ended it failed to obtain further evidence for lunar water ice.

Smart-1 (Current)

Smart-1 is ESA's first lunar mission, designed to test miniaturisation technology. It was launched in 2003, and is now on an extended mission until August 2006. It is the first craft to have discovered calcium on the moon from orbit, using X-ray spectrometer technology. Another major objective was to examine the so-called 'pics de lumière éternelle' (peaks of eternal light) at the poles of the moon (see right), and also craters that potentially never see the light of day and might therefore act as reservoirs for water ice. (Image courtesy of ESA)

LUNAR-A & SELENE (2005 - )

These two Japanese probes are both due to launch in August 2005. LUNAR-A will carry penetrators that will collect seismographic and thermal data from the Moon's interior, which should provide information about its internal structure. SELENE is an orbiter that will map the Moon's surface, as well as measuring the gravitational field of its dark side.

Mercury Probes

Mariner (1962-75)

The final Mariner Probe, no. 10, was launched in 1974 and used Venus as a gravity assist to Mercury. It returned close-up images of the Venetian atmosphere before flying on to Mercury. It managed three flybys of Mercury before running out of attitude control gas. It revealed the planet to be a heavily cratered world with a greater mass than previously thought.

Messenger (2011)

Messenger, only the second probe to Mercury, is due to orbit the innermost planet for one year, commencing in 2011 after flybys of the Earth, Venus and Mercury itself.

Venus Probes

Venera (1961-83)

Venera was a series of 16 Venus USSR probes. 14 were successful and particular achievements include Venera 7 (1970) which was the first probe to return data from the surface of another planet and Venera 9 which soft landed on Venus in 1975 and became the first spacecraft to land on another planet.

Mariner (1962-75)

The first Mariner probe, Mariner 1, was designed to fly past Venus in 1962, but unfortunately it was destroyed shortly after take off. Mariner 2 was more successful, it became the first US probe to fly past Venus in December of 1962. It comfirmed that Venus is a very hot world with a cloud-covered atmosphere made up of carbon-dioxide. Mariner 3 was launched in 1964 and was lost when the protective shroud failed to eject when the probe was placed in interplanetary space. It was intended to perform a Mars flyby with its sister probe, Mariner 4. Mariner 4 reached Mars in 1965 and took the first close up images of the planet's surface. The probe revealed a dead planet, with a cratered surface and little atmosphere.

Venus (1978)

The US Venus mission consisted of two components: Orbiter and Multiprobe. The orbiter was placed into orbit around Venus in 1978. The orbiter and four atmospheric probes made the first high-quality map of the surface of Venus.

Magellan (1989-94)

Magellan was launched by the US in 1989, and has mapped 98% of the surface of Venus. In 1994 just before it failed, the probe was sent into Venus's atmosphere to further study aerobraking techniques which can be used to make fuel savings in future missions.

Galileo and Cassini-Huygens (1990 and 1998)

Both of these spacecraft flew by Venus in a gravity-assist manoeuvre on their way to Jupiter and Saturn respectively.

Venus Express (2005-2006)

Venus Express is an ESA orbiter, following much the same format as Mars Express. It launched in November 2005 and arrived successfully in April 2006. Since its arrival it has observed a fascinating double vortex in the Venusian atmosphere at the South Pole.

Mars Probes

Mars (1962-1974)

Mars was a series of 7 Martian probes launched by the former USSR. Few were successful but some achievements were made such as the first successful soft landing on Mars, (Mars 3, 1971).

Mariner (1962-1975)

The US probes Mariners 5 and 6 performed fly pasts of Venus and Mars respectively in '67 and '69.These were followed by Mariner 7 which perfomed a further flypast of Mars in '69. The next Mariner probe was destroyed shortly after launch. Mariner 9 became the first craft to orbit Mars in 1971. It showed the planet had volcanoes, as well as giants canyon systems. It revealed evidence that water had once flowed across the surface and also took the first images of the two moons, Phobos and Deimos.

Viking (1975-1983)

The US Viking mission to Mars was made up of two spacecraft. The mission objectives were to obtain high resolution images of the surface, characterise the structure and composition of the atmosphere and surface, and to search for life on Mars. The images gave the most complete view of Mars to date. They showed volcanoes, canyons, cratered areas, and evidence of surface water. The planet could be divided into two areas: the northern low plains and the sourthern cratered highlands. The surface material at both sites was iron-rich clay. Temperatures varied between 150 and 250 Kelvin. The biological experiments showed no evidence of life at either landing site.

Mars Pathfinder (1997)

NASA's Mars Pathfinder mission was the beginning of a long series of Mars probes to help us understand about the planet. It consisted of a lander and rover. It was the first of NASA's 'faster, better and cheaper' missions and it was extremely successful.

Mars Global Surveyor (Current)

NASA's Mars orbiter space craft has been mapping the surface of Mars since 1999 and is now on an extended mission. It has also taken the first ever orbiter pictures of other spacecraft orbiting the same planet. Scientists working on the mission also developed an innovative technique to gain very high resolution pictures, by rolling the spacecraft at the same speed as the ground moves by underneath.

Mars Odyssey (Current)

Mars Odyssey was launched in 2001 and has now gone into overtime. It indicated that there may be as much as ten percent water in the surface, due to the presence of magnesium sulphate salts which are likely to store water under Mars-like conditions. The image is Mars Oddyssey, taken by Mars Global Surveyor.

Mars Express (Current)

Mars Express is ESA's Mars orbiter. It travelled to Mars in 2003, accompanied by the British lander Beagle2, which was sadly lost after it detached from Mars Express in December 2003. Mars Express is searching for sub-surface water on Mars. Its Fourier spectrometer also discovered Methane on Mars on 28th October 2004. The image, taken by Mars Express, shows signs of water erosion on Mars (courtesy of ESA).

Spirit and Opportunity (Current)

Spirit and Opportuity are NASA's twin rovers. They landed early in 2004, and have obtained some stunning images of the Martian surface. They too have been searching for evidence that there was once water on Mars. On opposite sides of the planet, Spirit discovered rocks heavily altered by water and Opportunity found evidence of an ancient body of water. They are now more than a year into an extended mission.

Mars reconnaissance Orbiter (2005 - )

NASA's latest Mars mission was scheduled for launch on August 10th 2005. It arrived safely on 10th March 2006 and will shrink its orbit over a period of 6 months.

Phoenix (2007 - )

Phoenix is NASA's lastest lander, currently searching for signs of life in the frozen Arctic of the Martian world. Phoenix has been scraping and analysing soil containing water ice, in order to discover more about the Martian climate in the past and present.

ExoMars

The first approved flagship mission of ESA's Aurora project, ExoMars will consist of an orbiter, descent module and rover. It is likely to present a significant technological challenge.

Probes to the Gas Giants

Pioneer (1973-1997)

The US Pioneer 10 was the first spacecraft to fly past Jupiter in 1973, and Pioneer 11 followed it in 1974 and went on to study Saturn in 1979. Pioneer was designed to test the ability of spacecraft to fly safely through the asteroid belt and Jupiter's magnetosphere. The asteroid belt was easy, but the probes were nearly fried by ions trapped in Jupiters magnetic field. This information was crucial to the success of the Voyager missions.

The last contact with Pioneer 11 was in November 1995. Pioneer 10 is still functioning but is no longer being tracked. The last data was received from it on the 31st march 1997. Both crafts are now heading off into interstellar space - the first manmade craft to do so. Both crafts have plaques, with information about Earth and the human race, bolted to the main frame.

Voyager (1977-)

The US Voyager probes were designed to fly past the outer planets of the solar system and send back images of the previously unphotographed planets. Voyager 1 flew past Jupiter and the Saturn. It then went to Titan for close up pictures. Voyager 2 flew by Jupiter, Saturn, Uranus and Neptune. It then took advantage of a once-every-189-years alignment to sling shot its way from outer planet to outer planet. Both probes have sent back information that has greatly increased our knowledge of the outer planets. As long as there are no unforeseen failures, Earth should be in contact with the probes until the year 2030.

Galileo (1989-1997)

In 1989 the NASA space shuttle Atlantis flight STS-34 launched the probe Galileo. The probe took infrared images of Venus, and images of the asteriod Ida, before continuing to Jupiter. Once in orbit it made extensive surveys of the Jovian moons and a probe descended into the atmosphere, providing our first direct evidence of the interior of a gas giant.

Ulysses (1990 - )

The objective of Ulysses was to put a probe into a heliocentric orbit, but in order to do this the spacecraft had to perform a gravity-assist orbit around Jupiter.

Cassini Huygens (1997 - )

Cassini-Huygens is a joint NASA/ESA mission to Saturn and its moon, Titan. Launched in 1997, the Cassini probe went into orbit around Saturn in July 2004, and Huygens landed on Titan in January 2005. Cassini has obtained some spectacular images of Saturn's rings, including images of resonance effects caused by the ring moons, and has returned photographs of lake-like features and possible volcanoes on Titan. Data from the Huygens probe has provoked scientists to re-evaluate their hypotheses on the structure of Titan, and they are further investigating the precise nature of the supposed 'liquid layer' of the moon. Cassini has recently discovered that another moon, Enceladus, displays signs of active ice vulcanism and is the smallest known body to do so.

Prometheus 1 (2015? - )

Prometheus 1 is the next proposed mission to Jupiter. Its earliest launch date is 2015, so it is still very much in the planning stage, but it is proposed that the spacecraft could orbit Ganymede, Callisto and Europa - three of Jupiter's four Galilean moons. It is believed that all three may have sub-surface oceans.

Probes to Pluto

NASA's New Horizons probe is due to launch in 2006. It will fly by both Pluto and Charon, and also enter the Kuiper belt where Quaoar was recently discovered.

Probes to comets

Giotto (1985-1992)

The Giotto probe was launched in 1985 by an Ariane rocket. It approached to within 540km of the nucleus of Comet Halley in 1986. The probe carried ten instruments and returned data until just before closest approach, when the downlink was temporarily lost. Giotto was damaged by high-speed dust encounters during the flyby and was placed into hibernation shortly afterwards. In 1990 Giotto was reactivated, but only three instruments were fully operational and four were partially operable. It made a close encounter with Earth in July 1990 and was then retargeted to make a successful flyby of comet Grigg-Skjellerup on July 10,1992.

Deep Space 1 (1998-2001)

Deep Space 1 was originally a probe designed to fly by an asteroid. Having succesfully completed this mission, it also flew by Comet Borelly. left, sending back useful images and scientific data.

Stardust (1999-2006)

Stardust flew past comet Wild 2 in 2004 and collected dust particles that will be returned to Earth in 2006.

Rosetta (2004 - 2014)

Rosetta will go into orbit around the comet 67P/Churyumov-Gerasimenko in 2014, and will release a small lander that will make the first ever controlled landing on the surface of a comet.

Deep Impact (2005 )

On July 4th 2005 the Deep Impact mother ship released a dustbin-sized piece of copper above comet Tempel-1. This impacted the comet, and the resulting debris was imaged by the mother ship. It is hoped that data from this mission will enable scientists to learn more about how comets are formed, and also to deduce whether life could have been brought to Earth on board a comet.