How many astronomical detectors have been launched by humans?

Interplanetary Vehicles

The following list only lists a series of aircraft related to interplanetary scientific research, and is far from a complete list of aircraft.

Past missions

Luna 2 Luna 2

Crash into the moon in 1959 (Soviet Union)

Luna 3 Luna 3

Obtained the first photo of the far side of the moon in 1959 (Soviet Union)

Mariner 2 Mariner 2

Became the first ship to successfully conduct a low-altitude flyby in December 1962 The information sent back by Venus' detectors proves that Venus is a hot star (800 degrees Fahrenheit, now revised to 900 degrees), and is covered by a thick cloud-like carbon dioxide atmosphere.

Mariner 3 Mariner 3

Launched on November 5, 1964. After entering interplanetary space, the protective covering failed to eject and disappeared. Unable to absorb solar energy with solar panels, the detector soon failed due to exhausted batteries, and it is still orbiting the sun to this day. It was originally intended to fly past Mars with Mariner 4.

Mariner 4 Mariner 4

Mariner 3’s sister probe arrived at Mars in 1965 and took 22 close-up photos of the Martian surface during its passage. The probe discovered a crater world with a much thinner atmosphere than expected. Scientists have concluded that Mars is a "dead" star from both a geological and biological perspective.

Mariner 9 Mariner 9

The sister probe of Mariner 8, which failed to launch, became the first spacecraft to orbit Mars in 1971 and returned the first large-scale data. Star information about the Red Planet, including giant volcanoes on the surface, the Grand Canyon system, and evidence that water once flowed on the planet. The probe also took several close-up photos of Mars' two small moons, Phobos and Deimos.

Apollo

6 man-made lunar landers and recovered lunar samples from 1969-72.

Luna 16 Luna 16

Automatically collected lunar samples back to Earth (Soviet Union) in 1970

Pioneer 10 and Pioneer 11 Pioneer 10 and 11

Pioneer 10 became the first spacecraft to fly by Jupiter in 1973, followed by Pioneer 11 in 1974. Then, in 1979, they became the first probes to study Saturn. Pioneers are also used to test the survival rate through the asteroid belt and Jupiter's giant magnetic field. In fact, it seems that the asteroid belt is really a piece of cake, but they were almost exploded by the ions in Jupiter's magnetic field. This information made the situation for the subsequent Travelers plan very serious.

Pioneer 11's RTG power system was damaged, and its last contact with Earth was in November 1995. Pioneer 10 is still working normally (but it's fast), but due to budget cuts, it can no longer be tracked regularly. The last time data was obtained from it was on March 31, 1997. They will be the first aircraft to enter interstellar space.

(The Pioneer Project was officially terminated on March 31, 1997, although the United States still contacts it from time to time. - Translation Annotation)

When they left the solar system , a 6*9-inch gold plaque will be ejected to the main frame of the aircraft.

Mariner 10 Mariner 10

It reached Mercury in 1974 with the help of Venus' gravity. The probe was the first to send back close-up photos of Venus' atmosphere in ultraviolet light, revealing many previously unseen details of the cloud cover and discovering that the entire cloud system orbits the planet every four Earth days. Mariner 10 made three flybys of Mercury in 1974-75 before running out of power. The flight revealed that Mercury is a cratered world with a much greater mass than originally estimated, and appears to have an iron core that accounts for 75% of its total mass.

Venera 7

In 1970, it became the first probe to send back data from the surface of another planet (Venus).

Venera 9

In 1975, a soft landing was made on Venus and pictures of the surface were sent back (Soviet Union). It was the first spacecraft to land on another planet.

Pioneer Venus

Orbiter and four atmospheric detectors; produced the first high-resolution map of the surface of Venus in 1978.

Viking 1 Viking 1

It was launched from Cape Canberra, Florida on August 20, 1975 by a TITAN 3E-CENTAUR D1 rocket. The probe entered Mars' orbit on June 19, 1976, and the landing device successfully landed on the slope of Chryse Planitia on July 20, 1976. Then, it immediately launched into a pre-programmed search for Martian microorganisms (people are still debating whether there are living things on Mars), and sent back incredible full-color images of the surrounding landscape. From this, scientists learned that the sky on Mars is slightly peach-pink, not the dark blue they originally thought (the sky is pink because red dust particles in the thin atmosphere reflect sunlight). The lander landed on a patch of red sand, with boulders stretching out in all directions, giving it the furthest range for photography.

Viking 2 Viking 2

Launched on September 9, 1975, entered Mars orbit on August 7, 1976, and touched down on Utopia Planitia on September 3, 1976 . Completing the same mission as its sister probe, the seismometer unexpectedly worked properly and recorded a Martian earthquake.

Viking Lander 1 made its last data transmission on November 11, 1982. JPL controllers spent six and a half months still unable to restore contact with it. All missions ended on May 21, 1983.

Interesting fact: The Viking 1 lander was named the Thomas A. Mutch Memorial Station in honor of the late leader of the lander imaging research team. The National Museum of Gas and Space in Washington, D.C., is entrusted with the safekeeping of the space station until a human expedition can join it.

Voyager 1 Voyager 1

Voyager 1 (top picture) launched on September 5, 1977, flew by Jupiter on March 5, 1979, 1980 It flew by Saturn on November 13, 2011. Voyager 2 launched on August 20, 1977 (earlier than Voyager 1), flew by Jupiter on August 7, 1979, flew by Saturn on August 26, 1981, flew by Uranus on January 24, 1986, and flew by Uranus on August 1989. It will fly by Neptune on January 8th. The outer planets slingshot every 189 years, and Voyager 2 took full advantage of this. In principle, Voyager 1 can also be used, but in order for it to approach Titan on the way, JPL flew directly to Pluto.

Between the two detector activities, we learned about these four giants. Knowledge of the planets and their moons expanded greatly. Voyager 1 and 2 discovered that Jupiter's atmospheric dynamic structure, lightning, and auroras are extremely complex, and they also discovered three new satellites. The two most surprising points are: Jupiter has a ring, and Io has active sulfur volcanoes, which have an important effect in Jupiter's magnetosphere.

When the two probes arrived at Saturn, they discovered more than 1,000 small rings and 7 moons, including the expected existence of the Shepherd satellite to ensure the stability of the ring structure. The climate is quite stable compared to Jupiter's: the giant jets rarely branch (a 33-year-old white spot/circle was discovered), Titan's atmosphere is smoky, and Mimas' appearance is also surprising. Surprising: A violent planetary collision left it shaped like a Death Star. The big surprise was the strange appearance of the halo: spikes, ribbons, spokes, unexpected and unexplained.

Voyager 2 Voyager 2

Thanks to the efforts of heroic engineers and programmers, it can continue its mission to Uranus and Neptune. Uranus has a monochromatic appearance, and what's strange is that the axis of its magnetic field is also highly deflected from its already highly skewed spin axis, making its magnetosphere weird. Ice straits were discovered on Titan, and Titan is a patchwork of strange terrains. 10 moons and more than 1 ring were discovered.

Compared with Uranus, Neptune has a very active climate and clouds come in various shapes. The halo arcs on a halo become sequins. In addition, 6 other satellites and 2 rings were discovered. Neptune's magnetic field axis is also tilted. Triton looks like a horned magnifying glass and appears to have many fountains. (Imagine what liquid at 38 K is like)

If no unforeseen failures occur, we will be able to stay in touch with them until 2030. Both aircraft had large amounts of hydrazine fuel. Voyager 1's propellant can be used until 2040, and Voyager 2's propellant can be used until 2034. The limiting factor is the RTG (Radioisotope Thermoelectric Generator). By the year 2000, UVS (ultraviolet spectrometer) instruments will run out of power. By 2010, remaining power prevented all field and particle instruments from operating simultaneously. At this point, an energy sharing scheme will be implemented, causing some of the field and particle instruments to work in turn with others. The aircraft can continue to operate in this state for about 10 years.

Eventually, there may be too little energy to sustain the aircraft properly.

Vega

The international project VENUS-HALLEY (Venus - Halley), launched in 1984, with an orbiter and a lander, made a close flight to Halley's Comet.

Phobos

Two spacecraft launched by the Soviet Union in 1988. One failed without warning and only a handful of images were sent back before the second one failed.

Giotto

Giotto was launched by ESA's Ariane-1 on July 2, 1985, and arrived only 540 kilometers from the core of Halley's Comet on March 13, 1986 ( The upper and lower error is 40 kilometers). The craft, which carried 10 instruments, including a multi-color camera, sent back a bit of data, but was soon shut down as it neared its destination and the connection was temporarily interrupted. Due to collision with dust at high speed, the aircraft was seriously damaged and declared to enter hibernation shortly after it entered the expected position and was fixed.

In April 1990, Giotto was reactivated. Three of the instruments were still operational, four were partially destroyed but inoperable, and the remainder, including the camera, were completely unusable. Giotto encountered Earth on July 2, 1990, and was redirected to comet Grigg-Skjellerup on July 10, 1992.

Clementine

A joint mission plan between the Ballistic Defense Organization (the predecessor of SDIO) and NASA to conduct flight testing of sensors developed by Lawrence Livermore for BMDO. The aircraft was manufactured by the Naval Survey Laboratory. It took off on January 25, 1994, and orbited the moon for a period of 425 kilometers to 2950 kilometers for two months. Its mission was to make maps. The vehicle has instruments such as UV and mid-IR mappers, as well as a lidar mapper to obtain the moon's mid-latitude altitude data. Earlier in May, scientists planned to fly the spacecraft out of lunar orbit to fly by the asteroid 1620 Geographos, but a failure stopped the attempt.

Ground controllers have resumed control of the aircraft, and its future exploration missions are still being considered.

Mars Observer

The Mars orbiter has a camera with a resolution of 1.5 meters per point. It was successfully launched on September 25, 1992 by the Titan III/TOS booster. When it was preparing to enter Mars orbit on August 21, 1993, communication was interrupted. The aircraft mission was nearly canceled (post-mortem analysis). The Mars Global Surveyor, a replacement mission that completed most of the science missions expected of MO, launched in November 1996.

Magellan

Launched in May 1989, it mapped 98% of the surface of Venus with a resolution of 300 meters and mapped 95% of the planet’s gravity field. picture. It is currently undergoing an 80-day air braking project to reduce the altitude and slow down the revolution speed. It has completed radar mapping work and gravity data collection. In the fall of 1994, before the end of the expected life of its radioisotope thermoelectric generator, it was deliberately sent into the atmosphere of Venus to do further aerobraking research and save most of its fuel for any future missions.

(More information, one page and another from JPL; status report from NSSDC)

Mars 96 Mars 96

A large orbiter The vehicle, which contained several landers, was originally called Mars 94. The launch failed on November 17, 1996. (The original Mars 96 attracted attention for a while, until Mars 98 was canceled shortly after.) (More information from MSSS and from IKI (Russia))

Ongoing missions

Voyagers 1 and 2 Voyagers 1 and 2

Can continue to work under control for more than 15 years, during which time they will travel through space until they fly out of the solar system. It is generally believed that the Voyagers will be able to operate until 2015 before the radioisotope thermoelectric generator fails. Their flight path is evidence that there are no planets beyond Pluto. Their next scientific discovery lies in finding the exact location of the edge of the sun's atmosphere. Low-frequency emissions from the edges of the Sun's atmosphere can be used to help travelers determine its location.

Voyagers use their ultraviolet spectrometers to map the boundaries of the Sun's atmosphere and study the interstellar winds it receives. Cosmic ray detectors detect the energy spectrum of cosmic rays emitted from outside the solar atmosphere.

Voyager 1 has surpassed the Pioneer 10 spacecraft and is currently the farthest man-made object from the earth.

Galileo Galileo

Jupiter’s orbiter and atmosphere probe is now in orbit around Jupiter. It will conduct further exploration of Jupiter's moons. It has now entered Jupiter's atmosphere and will provide us with direct data about the red gas giant.

Galileo has sent back decomposed photos of two asteroids 951 Gaspra and 243 Ida on its way to Jupiter. It also sent back the Shoemaker Levi that hit Jupiter from its unique perspective. Photos of Comet 9.

Efforts to deploy high-yield antennas (HGA) were abandoned; low-yield antennas could only transmit approximately 10 bits per second. JPL originally prepared a backup plan to use enhanced receiving antennas and high compression rate data (JPEG-like image compression method, a near-lossless compression method achieved with instruments) on the Deep Space Network spacecraft. Due to the low speed of the low-yield antenna, Galileo completed only 70% of its original scientific observations. At the same time, Jupiter has a strong climate influence, which makes it suffer a lot.

Galileo schedule (UTC time)

-------------

10/18/89 - Launched from space shuttle

02/09/90 - Fly past Venus

10/**/90 - Send back Venus data

12/08 /90 - First flyby of Earth

05/01/91 - Failed to open high-yield antenna

07/91 - 06/92 - First flyby of the asteroid belt

10/29/91 - Flyby of asteroid Gaspra

12/08/92 - Second flyby of Earth

05/93 - 11/ 93 - Second flyby of the asteroid belt

08/28/93 - Flyby of asteroid Ida

07/13/95 - Probe flies away

< p> 07/20/95 - Orbiter deviates from expected

12/07/95 - Meeting with Jupiter

06/27/96 06:30 - Ganymede-1

09/06/96 19:01 - Ganymede-2

11/04/96 13:30 - Callisto-3

11/06/96 18: 42 - Europa-3A (Unexpected meeting, on the same orbit as Callisto, 32,000 kilometers away from Callisto)

12/19/96 06:56 - Europa-4

01/20/97 01:13 - Europa-5A (flying 27,400 kilometers away)

02/20/97 17:03 - Europa-6

04/ 04/97 06:00 - Europa-7A (Unexpected meeting, on the orbit of Ganymede-7, 23,200 kilometers away)

04/05/97 07:11 - Ganymede-7

05/06/97 12:12 - Callisto-8A (Unexpected meeting, on the orbit of Ganymede-8, 33,500 kilometers away)

05/07/97 15:57 - Ganymede- 8

06/25/97 13:48 - Callisto-9

06/26/97 17:20 - Ganymede-9A (Unexpected meeting, Callisto 80,000 kilometers away -9 orbit)

09/17/97 00:21 - Callisto-10

11/06/97 21:47 - Europa-11 (more details)

The expansion mission of Galileo has been approved. If it goes well, it will focus on studying Europa in another two years.

(Education and Public Outreach (with pictures!); Galileo Home Page; Galileo Probe Home Page and more info from JPL; newsletter; web page; NSSDC page; Preliminary Galileo Probe results from JPL and ARC and LANL)

Hubble Space Telescope

It was launched in April 1990 and underwent adjustment and repairs in December 1993. Harbaugh can provide photos and spectra over a long period of time. This becomes an important alternative factor in obtaining higher-resolution data in planetary exploration.

For example, recent data from Hubble show that Mars is colder and drier now than during the Viking missions; Hubble data on Neptune show that its atmosphere is changing rapidly.

It was named in honor of the American astronomer Edward Hubble.

More information and photos about Hubble are available at the Space Telescope Science Institute. Harbaugh's newest images are being released with regularity. (This is a major history of the Hubble Space Telescope program. JPL has more Hubble information.)

Ulysses

are currently investigating the solar polar regions (European Space Agency Agency/NASA). Ulysses was launched aboard the Discovery spacecraft in October 1990. In February 1992, it was lifted out of the ecliptic plane by Jupiter's gravity. It has now completed its main task of observing the sun's poles. Its mission has been extended to another scope, which is to observe the poles of the sun during the period of maximum sunspot activity. Its aphelion is 5.2 AU, and surprisingly, its perihelion is about 1.5 AU—that's right, a spacecraft that studies the sun is generally farther from the sun than Earth is. It is expected to provide better data for studying the sun's magnetic field and solar wind.

Wind

After launch on November 1, 1994, NASA's Wind satellite will occupy a vantage point between the sun and the Earth, providing scientists with an excellent view of what is believed to be is an opportunity to study the massive flow of energy and momentum in the solar wind.

The main goal of this mission is to measure the mass, momentum and energy of the solar wind that is transmitted to the outer space of the Earth in some way. Although much has been learned from previous space programs about the nature of this massive transmission, it is necessary to collect large amounts of detailed information from key regions of Earth's outer space before scientists can understand the way planetary atmospheres respond to changes in the solar wind. of.

This launch is also the first time that Russian instruments are installed on an American space vehicle. This is the Konus Gamma ray spectrometer provided by the Russian Ioffe Association. It is one of two instruments on Wind. It studies the impact of cosmic gamma rays, not the solar wind. There is also a French instrument on board the spacecraft.

Initially, the satellite will orbit the Earth in a figure-eight shape with the help of the moon's gravitational field. Its farthest point from Earth will be 990,000 miles (1,600,000 kilometers), and its closest point will be at least 18,000 miles (29,000 kilometers).

The mission is that the Wind spacecraft will travel upstream from the Earth and insert it into a special halo of the solar wind, staying at a specific distance that allows Wind to maintain between the sun and the Earth. (Approximately 930,000 to 1,050,000 miles from Earth, or 1,500,000 to 1,690,000 kilometers).

NEAR

The Near-Earth Asteroid Rendezvous Project (NEAR) is committed to answering fundamental questions about the nature of near-Earth objects such as asteroids and comets between the orbits of Jupiter and Mars.

The NEAR spacecraft was launched on a Delta 2 rocket on February 17, 1996. It should arrive in orbit around the asteroid 433 Eros in early January 1999. It will then observe the rock mass for at least a year from an altitude of nearly 15 miles (24 kilometers). Eros is one of the largest and best-observed of the asteroids whose orbits cross the path of Earth. These asteroids are closely related to the numerous "main-belt" asteroids that orbit the sun in a vast circular orbit between Mars and Jupiter.

Mars Surveyor Program Mars Surveyor Program

The Mars Global Surveyor is the first mission of a new ten-year remotely operated Mars exploration program. This is called the Mars Exploration Plan. A series of active orbiters and landers will be launched every 26 months as Mars moves in line with Earth. The program is affordable, costing about $100 million per year. Providing the public with the latest global and close-up images of Mars. With the development of frontier space technology, higher scientific value can be obtained.

The Mars Global Surveyor will be a spacecraft orbiting the poles of Mars. It is designed to provide global maps of surface topography, mineral distribution and detection of global climate.

On November 7, 1996, it was launched with a Delta II expendable rocket from Cape Canaveral, Fla. This space flight is in an ecliptic orbit around Mars. That year, thruster ignition and air braking technology will be used to reach a nearly circular orbit above Mars' polar caps. Air braking, a technology pioneered by the Magellan program, uses atmospheric drag to slow down a spacecraft so that it reaches its final intended orbit. This would provide a way to reduce the fuel required to reach low altitude orbit around Mars. Pre-order operations are expected to begin in March 1999.

This spacecraft orbits Mars every two hours and maintains a "sun-synchronous" orbit. This will make the angle between the sun and the horizontal plane in each picture a constant value, so that the shadow cast by the noon sun will be Make the surface terrain particularly eye-catching. The spacecraft will carry a portion of the Mars Observer instrument box, which will be used to acquire data on Mars for an entire Martian year. One Martian year is equivalent to almost two Earth years. The spacecraft will serve as a data relay station and low-altitude probe for U.S. and international landers over the next three years.

Pathfinder Pathfinder

The Mars Pathfinder (formerly known as the Mars Environmental Survey or MESUR or Pathfinder) is NASA's second low-lying Cost of a planet discovery mission. The mission consists of a fixed landing module and a Sojourner-like surface rover. The original purpose of the mission was to demonstrate the feasibility of low-cost landing and exploration on the Martian surface. This goal will be achieved through testing of rovers and landers, landers and Earth information, and testing of imaging equipment and sensors.

Its scientific purposes include access to atmospheric science, distant and close-up images of the Earth's surface. It carries the goal of characterizing the Martian environment for further exploration. The vehicle will enter the Martian atmosphere and land on Mars without entering orbit around the planet. As it descends, it carries a parachute assembly, rocket and air bags, and takes atmospheric measurements. Before landing, the spacecraft will be surrounded by three triangular panels (petals). They unfold onto the ground after landing.

The Mars Pathfinder was launched on December 4, 1996, and successfully landed on Mars on July 4, 1997.

Cassini

Saturn's orbiter and Titan's atmospheric probe. Cassini is a joint NASA/ESA project. This project is designed to complete the exploration of the Saturn system using its Cassini Saturn orbiter and Huygens Titan probe. Cassini was launched aboard IV/Centaur on October 15, 1997. Before reaching Saturn, Cassini will undergo two Venus gravitational accelerations, one acceleration each for the Earth and Jupiter (a "VVEJGA" trajectory (Venus Venus Earth Jupiter Gravity Acceleration)), and arrive at Saturn on July 1, 2004.

Lunar Prospector

Lunar Prospector is the first NASA project to visit the moon in the past 30 years. It was launched on June 6, 1998, and within a month it would begin to answer long-standing questions about the Moon and its resources, structure, and origins. (Welcome to the Moon, Lunar Surveyor home page); More information from NSSDC

Future Missions

Mars Surveyor '98 Mars Surveyor 98

Mars Prospector 98 is the next generation of spacecraft sent to Mars. It consists of the orbiter launched on December 10, 1998 and the lander launched in June 1999. Building on information from the Mars Global Surveyor and Mars Pathfinder missions, the Mars 98 mission will continue to grow insights. The scientific theme of the 1998 Explorer program was "Volatiles and Climate History."

The orbiter of Mars Prospector 98 will arrive at Mars on September 23, 1999, and the lander will land on December 3, 1999.

Images obtained as the lander descends to the surface will determine the relationship between the geology and physics of the landing site. The Atmospheric LiDAR Experiment will determine the amount of dust in the Martian atmosphere above the landing site.

Stardust Stardust

Planned to be launched in February 1999, Stardust will fly very close to the comet and bring back material from the comet's tail for the first time in history. Earth for analysis by scientists worldwide. The plan is to fly by Comet Wild-2 in 2004 and return to Earth in 2006.

Europa Orbiter

As part of NASA's Ice and Fire Preprojects, the mission to send an aircraft to Europa is beginning to be arranged. It was designed to measure the thickness of surface ice and discover possible hidden liquid oceans. Using an instrument called a radar sounder that sends radio waves through the ice, the Europa orbiter's scientific spacecraft will be able to detect the interface between ice and water, possibly 1 kilometer below the surface. Other instruments will reveal surface details and internal layers. This mission will be the first step before sending out "hydrobots," or submarines that can melt and travel through the ice to explore the depths of the ocean floor.

(Home; see Europa Ocean Exploration)

Pluto-Kuiper Express

(Pluto-Kuiper Express or formerly Pluto-Kuiper Express) pair A brief, rapid, and relatively low-cost initial observation of Pluto, which has never been visited before. If licensed starting in 1998, it could launch in 2001. It is necessary to launch two space vehicles with a dead weight of less than 100 kilograms. They will be launched with Titan IV/Centaura or Proton rocket thrusters in 2001 (an additional solid recoil platform may be required). From 2006 to 2008, they will encounter Pluto and Charon (this depends on the choice of path). The flyby speed will be 12 to 18 kilometers per second, and the data will be recorded on the detector during the brief encounter and then slowly transmitted back to Earth over the next year or even beyond (this is due to the low energy, small size and distance of the antenna) due to distance). Russia's "Drop Zond" probe, which examines the atmosphere, will also be included.

Scientific purposes include mapping the global geology of Pluto and Charon's moons. Plot the sides of each object, and trace Pluto's atmosphere (the atmosphere condenses as Pluto moves away from the sun, so launching very early and minimizing flight time is demanding for this purpose). The 7-kilogram food device may include a CCD image camera, IR mapping spectrometer, ultraviolet spectrometer, and radio scientific occultation experimenter.

The PFF vehicle is a highly scaled-down version of a modern-sized outer space launch pad, breaking the trend of increasingly complex and expensive probes like Galileo and Cassini.

An article about PFF written by the designer appeared in the September and October 1994 issues of Planet Reporter, a bimonthly news letter from the planetary research community.

The amount of funding for this project has not yet been determined.

(More information from NASA; Pluto Direct Program; Pluto Direct Science)

Muses-C

The Japanese-managed mission will launch from an asteroid Collect samples on board and bring them back to Earth. This innovative mission will use new space technologies, including electric space thrusters, to send a space vehicle to the asteroid 4660 Nereus and release a JPL Research rover, which is the size of a leather shoe box, to the asteroid's surface. almost. The Muses-c spacecraft will also ignite the explosives inserted into the asteroid, collect samples ejected from the impact, and then bring the samples back to Earth in a container for laboratory study and analysis. This mission is expected to be launched in 2002.

Mercury Polar Flyby flies over the pole of Mercury

As a result of the renewed focus on Mercury, two related programs are developing towards possible discovery module missions. Discovery is NASA's solar system exploration vehicle with the purpose of "cheaper, better, faster". The total cost of these missions was capped at $150 million. The two Mercury missions are the Mercury Magnetic Pole Probe (MPF) and Hermes (Mercury Orbiter). The MPF's instruments include a neutron spectrometer (for detection of water), compound polarization radar (for detection of rock and ice), and cameras (for capturing magnetic field and hemispheric images that Mariner 10 could not capture). We believe that the spacecraft program that flies close to celestial objects for detection is a cheaper and more technically feasible solution. The MPF is designed to encounter Mercury only a few times at aphelion. At aphelion, an aircraft only needs to withstand 4 times the heat change between the sun and the earth. Mercury's orbit is eccentric so that it changes 11 times at perihelion. A surround has to withstand such conditions, which requires elaborate (and expensive) thermal and cold protection systems. Hermes is the result of the joint efforts of JPL and TRW***. If this is approved, it could launch in 1999.

(All missions not otherwise specified belong to NASA)