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Exploration of Mars

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Computer generated image of one of the two Mars Exploration Rovers which touched down on Mars in 2004.

The exploration of Mars has been an important part of the space exploration missions of the Soviet Union (later Russia), the United States, Europe, and Japan. Dozens of unmanned spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s. These missions were aimed at gathering data and answering questions about the red planet and its past that may yield further insight into Earth's past, present, and future.

The exploration of Mars has come at a considerable financial cost with roughly two-thirds of all spacecraft destined for Mars failing before completing or even beginning their missions. This high failure rate can be ascribed to the large number of things that can go wrong, but enough have either failed or lost communications for no apparent reason that some researchers half-jokingly speak of a Great Galactic Ghoul which subsists on a diet of Mars probes. This phenomenon is also known widely as the Mars Curse.

Questions to explore

Mars has long been the subject of human fascination. Early telescopic observations revealed color changes on the surface which were originally attributed to seasonal vegetation and linear features which were ascribed to intelligent design. These early and erroneous interpretations led to wide public interest in Mars. Other telescopic observations found Mars' two tiny moons, dry channels and depressions, polar ice caps, Olympus Mons, the solar system's tallest mountain, and Valles Marineris, the solar system's largest canyon system. These discoveries have only piqued further interest in the study and exploration of the red planet. Mars is a rocky planet, like Earth, that formed around the same time, yet with only half the diameter of Earth and a cold and desert-like surface. Among the questions asked by scientists are the following:

  1. How does the composition of Mars differ from the Earth's and how have the two planets evolved differently?
  2. How does the composition and state of the interior of Mars differ from the Earth's?
  3. Is Mars still geologically active?
  4. What natural resources are available at the surface for future human use?
  5. Was there an early dense atmosphere on Mars?
  6. Did Mars once have oceans?
  7. What changes in climate has Mars experienced over its geologic history and what caused those changes?
  8. How stable is the climate of Mars today?
  9. Did chemical evolution take place on Mars, leading to the formation of prebiotic organic molecules?
  10. Did chemical evolution lead to the formation of replicating molecules, i.e. life?
  11. If life once arose, is it to be found anywhere on Mars today?
  12. How did Phobos and Deimos come to be where they are? What geology and resources do they possess?

Launch windows

In order to understand the history of the robotic exploration of Mars it is important to note that launch windows occur at intervals of 2.135 years, i.e. 780 days (the planet's synodic period). Launch windows were / will be in:

  • November 1996 to December 1996
  • December 1998 to January 1999
  • April 2001
  • June to July 2003
  • August 2005
  • October 2007
  • December 2009

Early flyby probes and orbiters

Early Soviet missions

The Soviet space program launched two flyby probes towards Mars in October 1960, dubbed Mars 1960A and Mars 1960B, but both failed to reach Earth orbit. In 1962, three more Soviet probes failed — two in Earth orbit (Mars 1962A and Mars 1962B) and one losing communication with Earth en route to Mars (Mars 1). In 1964, the Soviet Zond 2 was another failed attempt to reach Mars. Later in 1974, Mars 5 reached Mars and sent back over sixty pictures of the area south of Valles Marineris, before a depressurisation ended the mission.

Mariner program

Taken from Mariner 4, the first close-up image ever taken of Mars shows an area about 330 km across by 1200 km from limb to bottom of frame.

In 1964, NASA's Jet Propulsion Laboratory made two attempts at reaching Mars. Mariner 3 and Mariner 4 were identical spacecraft designed to carry out the first flybys of Mars. Mariner 3 was launched on November 5, 1964, but the shroud encasing the spacecraft atop its rocket failed to open properly, and it failed to reach Mars. Three weeks later, on November 28, 1964, Mariner 4 was launched successfully on an eight-month voyage to the red planet.

Mariner 4 flew past Mars on July 14, 1965, providing the first close-up photographs of another planet. The pictures, gradually played back to Earth from a small tape recorder on the probe, showed lunar-type impact craters. Some of them seemed touched with frost in the chill of a Martian evening.

NASA continued the Mariner program with another pair of Mars flyby probes at the next launch window. These probes reached the planet in 1969. See Mariner 6 and 7 for details. During the following launch window the Mariner program again suffered the loss of one of a pair of probes. Mariner 9 successfully entered orbit about Mars, after the launch time failure of its sister ship, Mariner 8. When Mariner 9 reached Mars, it and two Soviet orbiters (Mars 2 and Mars 3, see Mars probe program below) found that a planet-wide dust storm was in progress. The mission controllers used the time spent waiting for the storm to clear to have the probe rendezvous with, and photograph, Phobos. When the storm cleared sufficiently for Mars' surface to be photographed by Mariner 9, the pictures returned represented a substantial advance over previous missions. These pictures were the first to offer evidence that liquid water might at one time have flowed on the planetary surface.

Landers and later missions

Mars probe program

In 1969, the Soviet Union prepared an ambitious 5-ton orbiter called M-69. Two copies of the probe were both lost in launch mishaps involving the new and powerful Proton rocket.

In 1971, shortly after Cosmos 419 failed to launch, the Soviet Union successfully sent Mars 2 and Mars 3, nearly a decade after the launch of Mars 1, all part of the Mars probe program. The Mars 2 and 3 probes each carried a lander, both arriving on Mars in 1971. The Mars 2 lander entered Mars' atmosphere at too steep an angle, causing it to crash, and the Mars 3 lander functioned for only 20 seconds after landing. They were the first human artifacts to touch down on Mars.

In 1973, the Soviet Union sent four more probes to Mars: the Mars 4 and Mars 5 orbiters and the Mars 6 and Mars 7 flyby/lander combinations. Of the four, only Mars 5 succeeded; it transmitted 60 images before suffering a transmitter failure. Mars 6's lander transmitted data during descent but failed on impact. Mars 4 and 7 both missed the planet.

Viking program

File:Vikinglander1-1.jpg
Viking Lander 1 landing site (click image for detailed description).

In 1976 the two Viking probes entered orbit about Mars and each released a lander module that made a successful soft landing on the planet's surface. The two missions returned the first color pictures and extensive scientific information. Measured temperatures at the landing sites ranged from 150 to 250 K, with a variation over a given day of 35 to 50 K. Seasonal dust storms, pressure changes, and movement of atmospheric gases between the polar caps were observed. A biology experiment produced possible evidence of life, but it was not corroborated by other on-board experiments. Most scientists believe there currently is no life on Mars.

While searching for a suitable landing spot for Viking 2's lander, the Viking 1 orbiter photographed the landform that constitutes the so-called "Face on Mars" on July 25, 1976.

The Viking program was a descendant of the cancelled Voyager program, whose name was later reused for a pair of outer solar system probes.

Phobos program

The Soviet Union went to Mars again in 1988 with the Phobos 1 and 2 probes to study the planet and its moons Phobos and Deimos. Phobos 1 lost contact on the way to Mars. Phobos 2 successfully photographed Mars and Phobos, including several striking images of Moon and Planet in the same frame; however, it failed just before it was set to release two landers on Phobos' surface.

Mars Global Surveyor

This image from Mars Global Surveyor spans a region about 1500 meters across. Gullies, similar to those formed on Earth, are visible from Newton Basin in Sirenum Terra (NASA).

After the 1992 failure of NASA's Mars Observer orbiter, NASA retooled and launched Mars Global Surveyor. This mission was the first successful United States mission, and the first fully successful mission overall, to the red planet in two decades when it launched November 7, 1996, and entered orbit on September 12, 1997. After a year and a half trimming its orbit from a looping ellipse to a circular track around the planet, the spacecraft began its primary mapping mission in March 1999. It has observed the planet from a low-altitude, nearly polar orbit over the course of one complete Martian year, the equivalent of nearly two Earth years. Mars Global Surveyor completed its primary mission on January 31, 2001, and is now in an extended mission phase.

The mission has studied the entire Martian surface, atmosphere, and interior, and has returned more data about the red planet than all other Mars missions combined. These valuable data are archived and available publicly. [1]

Among key scientific findings so far, Global Surveyor has taken pictures of gullies and debris flow features that suggest there may be current sources of liquid water, similar to an aquifer, at or near the surface of the planet. Similar channels on Earth are formed by flowing water, but on Mars the temperature is normally too cold and the atmosphere too thin to sustain liquid water. Nevertheless, many scientists hypothesize that liquid groundwater can sometimes surface on Mars, erode gullies and channels, and pool at the bottom before freezing and evaporating.

Magnetometer readings show that the planet's magnetic field is not globally generated in the planet's core, but is localized in particular areas of the crust. New temperature data and closeup images of the Martian moon Phobos show its surface is composed of powdery material at least 1 metre (3 feet) thick, caused by millions of years of meteoroid impacts. Data from the spacecraft's laser altimeter have given scientists their first 3-D views of Mars' north polar ice cap.

Mars Pathfinder

File:Mars Twin Peaks (1024px).jpg
"Ares Vallis" as photographed by Mars Pathfinder (click image for detailed description).

The Mars Pathfinder spacecraft, launched one month after Global Surveyor, landed on July 4, 1997. Its landing site was an ancient flood plain in Mars' northern hemisphere called Ares Vallis, which is among the rockiest parts of Mars. It carried a tiny remote-controlled rover called Sojourner, which traveled a few meters around the landing site, exploring the conditions and sampling rocks around it. Newspapers around the world carried images of the lander dispatching the rover to explore the surface of Mars in a way achieved only twice previously by the Russian Lunokhod rovers on the moon 30 years before (the Lunokhods covered considerably greater distances also: 11km and 37km, repectively).

Until the final data transmission on September 27, 1997, Mars Pathfinder returned 16,500 images from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and soil and extensive data on winds and other weather factors. Findings from the investigations carried out by scientific instruments on both the lander and the rover suggest that Mars was at one time in its past warm and wet, with water existing in its liquid state and a thicker atmosphere. The mission website was the most heavily-trafficked up to that time.

Spate of failures

Following the success of Global Surveyor and Pathfinder, another spate of failures occurred in 1998 and 1999, with the Japanese Nozomi orbiter and NASA's Mars Climate Orbiter, Mars Polar Lander, and Deep Space 2 penetrators all suffering various fatal errors. Mars Climate Orbiter is infamous for Lockheed Martin engineers mixing up the usage of imperial units with metric units, causing the orbiter to burn up while entering Mars' atmosphere.

Mars Odyssey

In 2001 the run of bad luck ended when NASA's Mars Odyssey orbiter arrived. Its mission is to use spectrometers and imagers to hunt for evidence of past or present water and volcanic activity on Mars. In 2002, it was announced that the probe's gamma ray spectrometer and neutron spectrometer had detected large amounts of hydrogen, indicating that there are vast deposits of water ice in the upper three meters of Mars' soil within 60° latitude of the south pole.

Mars Express and Beagle 2

File:Marsexpressimage.jpg
Mars Express orbiter image, oblique view generated from stereoscopic data

On June 2, 2003, the European Space Agency's Mars Express set off from Baikonur Cosmodrome to Mars. The Mars Express craft consists of the Mars Express Orbiter and the lander Beagle 2. Although the landing probe was not designed to move, it carried a digging device and the smallest mass spectrometer created to date, as well as a range of other devices, on a robotic arm in order to accurately analyse soil beneath the dusty surface.

The orbiter entered Mars orbit on December 25, 2003, and Beagle 2 entered Mars' atmosphere the same day. However, attempts to contact the lander failed. Communications attempts continued throughout January, but Beagle 2 was declared lost in mid-February, and a joint inquiry was launched by the UK and ESA. Nevertheless, Mars Express Orbiter confirmed the presence of water ice and carbon dioxide ice at the planet's south pole. NASA had previously confirmed their presence at the north pole of Mars.

Mars Exploration Rovers

Shortly after the launch of Mars Express, NASA sent a pair of twin rovers toward the planet as part of the Mars Exploration Rover Mission. On 10 June 2003, NASA's MER-A (Spirit) Mars Exploration Rover was launched. It successfully landed in Gusev Crater (believed once to have been a crater lake) on 3 January 2004. It examined rock and soil for evidence of the area's history of water. On July 7, 2003, a second rover, MER-B (Opportunity) was launched. It landed on 24 January 2004 in Meridiani Planum (where there are large deposits of hematite, indicating the presence of past water) to carry out similar geological work.

Part of a 360 degree panorama photo of the Gusev crater landing site, taken by NASA's Spirit Rover in 2004

Despite a temporary loss of communication with the Spirit Rover (believed to have been caused by corrupted flash memory) delaying exploration for several days, both rovers eventually began exploring their landing sites. The rover Opportunity landed in a particularly interesting spot, a crater with bedrock outcroppings. In fast succession mission team members announced on 2 March that data returned from the rover showed that these rocks were once "drenched in water", and on 23 March that it was concluded that they were laid down underwater in a salty sea. This represented the first strong direct evidence for liquid water being on Mars at some time in the past.

Towards the end of July 2005, it was reported by the Sunday Times that the rovers may have carried the bacteria Bacillus safensis to Mars. According to one NASA microbiologist, this bacteria could survive both the trip and conditions on Mars. A book containing this claim, Out of Eden by Alan Burdick, is due to be published in the United Kingdom. Despite efforts to sterilise both landers, neither could be assured to be completely sterile.[1]

As of March 2006, both rovers are still healthy, though starting to show their ages in ways that require occasional intervention from Earth, and discovering new things, including Heat Shield Rock, the first meteorite to be discovered on another planet.

Mars Reconnaissance Orbiter

Main article: Mars Reconnaissance Orbiter

Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit. The $720 million USD spacecraft was built by Lockheed Martin under the supervision of the Jet Propulsion Laboratory, launched August 12, 2005, and attained Martian orbit on March 10, 2006.

The MRO contains a host of scientific instruments such as the HiRISE camera, CRISM, and SHARAD. The HiRISE camera will be used to analyze Martian landforms, whereas CRISM and SHARAD will detect water, ice, and minerals on and below the surface. Additionally, MRO will pave the way for upcoming generations of spacecraft through daily monitoring of Martian weather and surface conditions, searching for future landing sites, and testing a new telecommunications system that will enable the orbiter to send and receive information at an unprecedented bitrate. Data transfer to and from the spacecraft will occur faster than all previous interplanetary missions combined and allowing it to serve as an important relay satellite for future missions.

Future Missions

The next mission to Mars is the Phoenix Mars lander, expected to launch in 2007.

It should be followed by a (or a couple of) more capable rovers in 2009 or 2011 and by the European ExoMars mission in 2011. A second Scout mission should also be selected soon for 2011.

In addition, NASA plans to launch a proposed rover, the Astrobiology Field Laboratory in 2016.

Russia is still planning to launch its Phobos-Grunt probe in 2009.

The ESA is also planing a mission in 2011. The Exomars mission should obtaining soil samples from upto 2 meters deepth and make a extensive search for organic and biochemical substances.

Mars Curse

The high failure rate of NASA and other governmental agencies in their attempts to explore Mars has become known as the Mars Curse. See below for a full list of launch attempts to Mars.

By the spring of 2006, of 37 launch attempts to reach the planet, only 18 have succeeded. Eleven of the missions included attempts to land on the surface, but only six transmitted data once on the surface, and of those only one was non-American (Russian), which lost contact within 20 seconds of landing. Some suggest, mostly in jest, that there is actually some force trying to prevent or punish the exploration of Mars. The Galactic Ghoul is a fictional space monster that consumes Mars probes, a term coined in 1997 by Time Magazine journalist Donald Neff. [2] [3]

Manned missions

Many people, from Wernher von Braun on, have long advocated a manned mission to Mars as the next logical step for a manned space program after lunar exploration. Aside from the prestige such a mission would bring, advocates argue that humans would be easily able to outperform robotic explorers, justifying the expenses.

Because of the distance between Mars and Earth, the mission would be much more risky and more expensive than past manned flights to the Moon. Supplies and fuel would have to be prepared for a 2-3 year round trip and the spacecraft would have to be designed with at least partial shielding from intense solar radiation. A proposal called Mars Direct, advocated by Robert Zubrin of the Mars Society, is believed by many to be the most practical and affordable plan for a manned Mars mission.

United States President George W. Bush announced an initiative of manned space exploration on January 14, 2004, known as the Vision for Space Exploration. It includes a manned return to the moon by 2015 at the earliest, and suggests that manned missions to Mars may become a possibility at some point in the future. The European Space Agency has the long-term vision of sending a human mission to Mars by 2030, the Aurora Programme.

In the even longer term (centuries hence), some scientists believe Mars to be a good candidate for terraforming and human colonization, though other prominent skeptics (such as Robert L. Park) dispute the practicality of both. Many scientists have argued that if life is found on Mars, all human activities on the planet should be carried out with the goal of preservation in mind. Others argue that the presence of life on Mars would imply that life is prevalent throughout the universe; decreasing the relative importance of Martian microbes.

Timeline of Mars exploration

Dates listed are spacecraft launch dates.

Mission Launch Termination Objective Result
Marsnik 1 (Mars 1960A) 10 October 1960 10 October 1960 Flyby Launch failure
Marsnik 2 (Mars 1960B) 14 October 1960 14 October 1960 Flyby Launch failure
Sputnik 22 (Mars 1962A) 24 October 1962 24 October 1962 Flyby Broke up shortly after launch
Mars 1 1 November 1962 21 March 1963 Flyby Some data collected, but lost contact before reaching Mars
Sputnik 24 (Mars 1962B) 4 November 1962 January 1963 Lander Failed to leave Earth's orbit
Mariner 3 5 November 1964 5 November 1964 Flyby Failure during launch ruined trajectory. Currently in solar orbit.
Mariner 4 28 November 1964 21 December 1967 Flyby Success
Zond 2 30 November 1964 May 1965 Flyby Lost contact
Mariner 6 25 February 1969 August 1969 Flyby Success
Mariner 7 27 March 1969 August 1969 Flyby Success
Mars 1969A 27 March 1969 27 March 1969 Orbiter Launch failure
Mars 1969B 2 April 1969 2 April 1969 Orbiter Launch failure
Mission Launch Termination Objective Result
Mariner 8 8 May 1971 8 May 1971 Orbiter Launch failure
Cosmos 419 10 May 1971 12 May 1971 Orbiter Launch failure
Mars 2 19 May 1971 22 August 1972 Orbiter Success
27 November, 1971 Rover[4] Crash landed on surface of Mars
Mars 3 28 May 1971 22 August, 1972 Orbiter Success
2 December, 1971 Rover[4] Landed softly, but ceased transmission within seconds
Mariner 9 30 May 1971 May 1972 Orbiter Success
Mars 4 21 July 1973 February 1974 Orbiter Did not enter orbit, but made a close flyby
Mars 5 25 July 1973 21 February 1974 Orbiter Partial success. Entered orbit, and returned data, but failed within 9 days
Mars 6 5 August 1973 12 March, 1974 Lander Partial success. Data returned during descent, but not after landing on Mars
Mars 7 9 August 1973 9 March 1974 Lander Landing probe separated prematurely; entered heliocentric orbit.
Viking 1 20 August 1975 17 August 1980 Orbiter Success
13 November 1982 Lander Success
Viking 2 9 September 1975 25 July 1978 Orbiter Success
11 April, 1980 Lander Success
Phobos 1 7 July 1988 2 September 1988 Orbiter Contact lost en route to Mars
Phobos lander Not deployed
Phobos 2 12 July 1988 27 March 1989 Orbiter Partial success: entered orbit and returned some data. Contact lost just before deployment of landers
2 Phobos landers Not deployed
Mission Launch Termination Objective Result
Mars Observer 25 September 1992 21 August 1993 Orbiter Lost contact just before arrival
Mars Global Surveyor 7 November 1996 Currently operational Orbiter Success
Mars 96 16 November 1996 17 November 1996 Orbiter / landers Launch failure
Mars Pathfinder 4 December 1996 27 September 1997 Lander / rover Success
Nozomi (Planet-B) 3 July 1998 9 December 2003 Orbiter Complications en route; Never entered orbit
Mars Climate Orbiter 11 December 1998 23 September 1999 Orbiter Crash landed on surface due to metric-imperial mix-up
Mars Polar Lander 3 January 1999 3 December 1999 Lander Lost contact just before arrival
Deep Space 2 (DS2) Landers
Mission Launch Termination Objective Result
2001 Mars Odyssey 7 April 2001 Currently operational Orbiter Success
File:Logo ESA.png Mars Express Orbiter 2 June 2003 Currently operational Orbiter Success
File:Logo ESA.png Beagle 2 25 December 2003 Lander Lost contact upon landing
Spirit rover 10 June 2003 Currently operational Rover Success
Opportunity rover 7 July 2003 Currently operational Rover Success
File:Logo ESA.png Rosetta 2 March 2004 Currently operational Flyby Currently en route
Mars Reconnaissance Orbiter 12 August 2005 Currently operational Orbiter Success

Planned missions

Cancelled missions

See also

References

  1. ^ "It's one small step for a bug, a giant red face for NASA". The Sunday Times (UK). Retrieved 2006-06-17.
  2. ^ "The Depths of Space: The Story of the Pioneer Planetary Probes (2004)" from The National Academies Press. URL accessed April 7, 2006.
  3. ^ "Uncovering the Secrets of Mars" (first paragraph only). Time July 14, 1997 Vol. 150 No. 2. URL accessed April 7, 2006.
  4. ^ a b "The First Rover on Mars - The Soviets Did It in 1971" The Planetary Report July/August 1990 issue. URL accessed March 30, 2006.
  5. ^ "NASA MEPAG: Mars Science and Telecommunications Orbiter (DRAFT)". NASA. Retrieved 2006-06-19.
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