Exploration of Mars

Viking Lander 2 site May 1979

Viking Lander 1 site February 1978

The exploration of Mars has been an important part of the space exploration programs of the Soviet Union, the United States, Europe, and Japan. Dozens of robotic spacecraft, including orbiters, landers, and rovers, have been launched toward Mars since the 1960s. These missions were aimed at gathering data about current conditions and answering questions about the history of Mars as well as a preparation for a possible human mission to Mars. The questions raised by the scientific community are expected to not only give a better appreciation of the red planet but also yield further insight into the past, and possible future, of Earth.

The exploration of Mars has come at a considerable financial cost with roughly two-thirds of all spacecraft destined for Mars failing before completing their missions, with some failing before they even begin. Such a high failure rate can be attributed to the complexity and large number of variables involved in an interplanetary journey, and has led researchers to jokingly speak of The Great Galactic Ghoul ^[1] which subsists on a diet of Mars probes. This phenomenon is also informally known as the Mars Curse.^[2] As of July 2011, there is one functioning piece of equipment on the surface of Mars beaming signals back to Earth: the Opportunity rover.

In October 2009, an agreement was signed between United States' space agency, NASA, and Europe's space agency, ESA in order to increase cooperation and expand collective capabilities, resources and expertise to continue the exploration of Mars; this agreement is named the Mars Exploration Joint Initiative (MEJI).^[3][4]

The planet Mars

Computer-generated image of Spirit Mars Exploration Rover which touched down in Gusev Crater in 2004.

Real image from Mars, part of a panorama taken by the Spirit rover in 2004

Heat Shield Rock (Meridiani Planum) is examined by Opportunity rover (MER-B) in 2005

Main article: Mars

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 as well as apparent linear features which were ascribed to intelligent design. These early and erroneous interpretations led to widespread public interest in Mars. Further telescopic observations found Mars' two moons - Phobos and Deimos, the polar ice caps and the feature now known as Olympus Mons, the solar system's tallest mountain.^[5] These discoveries 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 far thinner atmosphere, it has a cold and desert-like surface. It is notable, however, that although the planet has only one quarter of the surface area of the Earth, it has about the same land area, since only one quarter of the surface area of the Earth is land.

Launch windows

In order to understand the history of the robotic exploration of Mars it is important to note that minimum-energy launch windows occur at intervals of approximately 2.135 years, i.e. 780 days (the planet's synodic period with respect to Earth). This is a consequence of the Hohmann transfer orbit for minimum-energy interplanetary transfer. The slight inclination and eccentricity of Mars' orbit relative to Earth's orbit means that the minimum energy launch date differs from that implied by the synodic period slightly. Launch window width is subject to vehicle constraints but are typically on the order of one month wide. The windows for recent/future years were/will be centred on the following dates:^{[citation needed]}

• 18 November 1996 (MJD 50405)
• 22 January 1999 (MJD 51200)
• 19 April 2001 (MJD 52018)
• 5 June 2003 (MJD 52795)
• 10 August 2005 (MJD 53592)
• 21 September 2007 (MJD 54364)
• 15 October 2009 (MJD 55119)
• 7 November 2011 (MJD 55872)
• 2 January 2014 (MJD 56659)

Minimum energy inbound (Mars to Earth) launch windows also occur at similar intervals.^{[citation needed]}

In addition to these minimum-energy trajectories, which occur when the planets are aligned so that the Earth to Mars transfer trajectory goes halfway around the Sun, an alternate trajectory which has been proposed goes first inward toward Venus orbit, and then outward, resulting in a longer trajectory which goes about 360 degrees around the Sun ^{[6][Full citation needed]}.

Early flyby probes and orbiters

Early Soviet missions

Main article: Mars 1M

Main article: Mars 1

Mars 1M spacecraft

The Mars 1M program (sometimes dubbed Marsnik in Western media) was the first Soviet unmanned spacecraft interplanetary exploration program, which consisted of two flyby probes launched towards Mars in October 1960, Mars 1960A and Mars 1960B (also known as Korabl 4 and Korabl 5 respectively). After launch, the third stage pumps on both launchers were unable to develop enough thrust to commence ignition, so Earth parking orbit was not achieved. The spacecraft reached an altitude of 120 km before reentry.

Mars 1962A was a Mars fly-by mission, launched on October 24, 1962 and Mars 1962B a lander mission, launched in late December of the same year both failed from either breaking up as they were going into Earth orbit or having the upper stage explode in orbit during the burn to put the spacecraft into the Mars trajectory.

Mars 1 (1962 Beta Nu 1) an automatic interplanetary station launched to Mars on November 1, 1962 was the first probe of the Soviet Mars probe program. Mars 1 was intended to fly by the planet at a distance of about 11,000 km and take images of the surface as well as send back data on cosmic radiation, micrometeoroid impacts and Mars' magnetic field, radiation environment, atmospheric structure, and possible organic compounds. Sixty-one radio transmissions were held, initially at two day intervals and later at 5 days in which a large amount of interplanetary data was collected. On 21 March 1963, when the spacecraft was at a distance of 106,760,000 km from Earth, on its way to Mars, communications ceased, due to failure of the spacecraft's antenna orientation system.

In 1964, both Soviet probe launches, of Zond 1964A on June 4, and Zond 2 on November 30, (part of the Zond program), resulted in failures. Zond 1964A had a failure at launch, while communication was lost with Zond 2 en route to Mars after a mid-course maneuver, in early May 1965.

The USSR intended to have the first artificial satellite of Mars beating the planned American Mariner 8 and Mariner 9 martian orbiters. But on May 5, 1971 Cosmos 419 (Mars 1971C), a heavy probe of the Soviet Mars program M-71, failed on launch. This spacecraft was designed as an orbiter only, while the second and third probes of project M-71, Mars 2 and Mars 3, were multi-aimed combinations of orbiter and lander.

Mariner program

Main article: Mariner program

The first close-up images taken of Mars in 1965 from Mariner 4 show an area about 330 km across by 1200 km from limb to bottom of frame.

Mariner Crater, as seen by Mariner 4. The location is Phaethontis quadrangle.

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 a 7½-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.

NASA continued the Mariner program with another pair of Mars flyby probes, Mariner 6 and 7, at the next launch window. These probes reached the planet in 1969. 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, the first spacecraft ever to do so, 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.

Viking program

The Viking Orbiters caused a revolution in our ideas about water on Mars. Huge river valleys were found in many areas. They showed that floods of water carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers. Areas of branched streams, in the southern hemisphere, suggested that rain once fell.^[7][8][9]

The images below, some of the best from the Viking Orbiters, are mosaics of many small, high resolution images. Click on the images for more detail. Some of the pictures are labeled with place names.

• 

  Streamlined Islands seen by Viking showed that large floods occurred on Mars. Image is located in Lunae Palus quadrangle.

• 

  Tear-drop shaped islands caused by flood waters from Maja Valles, as seen by Viking Orbiter. Image is located in Oxia Palus quadrangle. The islands are formed in the ejecta of Lod Crater, Bok Crater, and Gold Crater.

• 

  Scour Patterns, located in Lunae Palus quadrangle, were produced by flowing water from Maja Vallis, which lies just to the left of this mosaic. Detail of flow around Dromore Crater is shown on the next image.

• 

  Great amounts of water were required to carry out the erosion shown in this Viking image. Image is located in Lunae Palus quadrangle. The erosion shaped the ejecta around Dromore Crater.

• 

  Waters from Vedra Vallis, Maumee Vallis, and Maja Vallis went from Lunae Planum on the left, to Chryse Planitia on the right. Image is located in Lunae Palus quadrangle and was taken by Viking Orbiter.

• 

  Area around Northern Kasei Valles, showing relationships among Kasei Valles, Bahram Vallis, Vedra Vallis, Maumee Vallis, and Maja Valles. Map location is in Lunae Palus quadrangle and includes parts of Lunae Planum and Chryse Planitia.

• 

  The ejecta from Arandas Crater acts like mud. It moves around small craters (indicated by arrows), instead of just falling down on them. Craters like this suggest that large amounts of frozen water were melted when the impact crater was produced. Image is located in Mare Acidalium quadrangle and was taken by Viking Orbiter.

• 

  This view of the flank of Alba Patera shows several channels/troughs. Some channels are associated with lava flows; others are probably caused by running water. A large trough or graben turns into a line of collapse pits. Image is located in Arcadia quadrangle and was taken by Viking Orbiter.

• 

  Branched channels in Thaumasia quadrangle, as seen by Viking Orbiter. Networks of channels like this are strong evidence for rain on Mars in the past.

• 

  The branched channels seen by Viking from orbit strongly suggested that it rained on Mars in the past. Image is located in Margaritifer Sinus quadrangle.

• 

  Ravi Vallis, as seen by Viking Orbiter. Ravi Vallis was probably formed when catastrophic floods came out of the ground to the right (chaotic terrain). Image located in Margaritifer Sinus quadrangle.

Surface missions

Main article: Mars landing

The following is a map of landings on Mars.

The first image transmitted by the Viking 1 Lander from the surface of Mars, showing the craft's footpad.

The Soviet Union intended to beat the USA by sending landers first in the Mars probe program M-69 in 1969, but both probes of the new heavy 5-ton design, Mars 1969A and Mars 1969B, failed at launch.

The first probes to impact and land on Mars were the Soviet Union's Mars 2 and Mars 3, as part of the Mars probe program M-71 in 1971. Each carried a lander. The Mars 2 lander crashed; Mars 3 was the first successful lander but stopped transmitting data and images from the surface after 15 seconds of operation.

Mars 6 and Mars 7 landers on the next Soviet Mars probe program M-73 failed their missions in 1974; the first impacted on the surface, while the second missed the planet.

The first landers to successfully accomplish their missions were the American Viking 1 and Viking 2 in 1976.

Mars Curse

The high failure rate of missions launched from Earth attempting to explore Mars has become informally known as the "Mars Curse" or "Martian Curse". The "Galactic Ghoul"^[10] or "Great Galactic Ghoul" is a fictional space monster jokingly said to consume Mars probes, a term coined in 1997 by Time Magazine journalist Donald Neff.^[11][12][13]

Of 38 launches from Earth in an attempt to reach the planet, only 19 succeeded, a success rate of 50%. Twelve of the missions included attempts to land on the surface, but only seven transmitted data after landing.

The majority of the failed missions occurred in the early years of space exploration and were part of the Soviet and later Russian Mars probe program that suffered several technical difficulties, other than the largely successful Venera program for the exploration of Venus.

Modern missions have an improved success rate; however, the challenge, complexity and length of the missions make it inevitable that failures will occur.^[14]

The U.S. NASA Mars exploration program has had a somewhat better record of success in Mars exploration, achieving success in 13 out of 20 missions launched (a 65% success rate), and succeeding in six out of seven (an 86% success rate) lander missions.

Manned missions

Main article: Manned mission to Mars

Many people 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 easily be able to outperform robotic explorers, justifying the expense. Aerospace engineer Bob Zubrin is one of the main proponents of such missions. Some critics contend, however, that robots can perform better than humans at a fraction of the expense. If life exists on Mars, a manned mission could contaminate it by introducing earthly microbes, so robotic exploration would be preferable.^[15] A list of hypothetical or proposed manned Mars missions is located at manned mission to Mars.

Timeline of Mars exploration

mission type	success rate	success	partial success	launch failure	failed in route	failed to orbit/land
flyby	45%	5		4	2
orbiter	50%	9	2	5	3	3
lander	30%	3			3	4
rover	80%	3	1			1
sample return	0%				1
total	47%	20	3	9	9	8

Mission (1960–1969)	Launch	Arrival at Mars	Termination	Elements	Result
Mars 1960A	10 October 1960		10 October 1960	Flyby	Launch failure
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, flyby at approx. 193,000 km
Sputnik 24 (Mars 1962B)	4 November 1962		19 January 1963	Lander	Failed to leave Earth's orbit
Mariner 3	5 November 1964		5 November 1964	Flyby	Failure during launch ruined trajectory
Mariner 4	28 November 1964	14 July 1965	21 December 1967	Flyby	Success (first successful flyby)
Zond 2	30 November 1964		May 1965	Flyby	Communication lost three months before reaching Mars
Mariner 6	25 February 1969	31 July 1969	August 1969	Flyby	Success
Mariner 7	27 March 1969	5 August 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 (1970–1989)	Launch	Arrival at Mars	Termination	Elements	Result
Mariner 8	8 May 1971		8 May 1971	Orbiter	Launch failure
Cosmos 419 (Mars 1971C)	10 May 1971		12 May 1971	Orbiter	Launch failure
Mariner 9	30 May 1971	13 November 1971	27 October 1972	Orbiter	Success (first successful orbit)
Mars 2	19 May 1971	27 November 1971	22 August 1972	Orbiter	Success
			27 November 1971	Lander, rover[16]	Crashed on surface of Mars
Mars 3	28 May 1971	2 December 1971	22 August 1972	Orbiter	Success
			2 December 1971	Lander, rover[16]	Partial success. First successful landing; landed softly but ceased transmission within 15 seconds
Mars 4	21 July 1973	10 February 1974	10 February 1974	Orbiter	Could not enter orbit, made a close flyby
Mars 5	25 July 1973	2 February 1974	21 February 1974	Orbiter	Partial success. Entered orbit and returned data, but failed within 9 days
Mars 6	5 August 1973	12 March 1974	12 March 1974	Lander	Partial success. Data returned during descent but not after landing on Mars
Mars 7	9 August 1973	9 March 1974	9 March 1974	Lander	Landing probe separated prematurely; entered heliocentric orbit
Viking 1	20 August 1975	20 July 1976	17 August 1980	Orbiter	Success
			13 November 1982	Lander	Success
Viking 2	9 September 1975	3 September 1976	25 July 1978	Orbiter	Success
			11 April 1980	Lander	Success
Phobos 1	7 July 1988		2 September 1988	Orbiter	Contact lost while on route to Mars
				Lander	Not deployed
Phobos 2	12 July 1988	29 January 1989	27 March 1989	Orbiter	Partial success: entered orbit and returned some data. Contact lost just before deployment of landers
				Landers	Not deployed
Mission (1990–1999)	Launch	Arrival at Mars	Termination	Elements	Result
Mars Observer	25 September 1992	24 August 1993	21 August 1993	Orbiter	Lost contact just before arrival
Mars Global Surveyor	7 November 1996	11 September 1997	5 November 2006	Orbiter	Success
Mars 96	16 November 1996		17 November 1996	Orbiter, lander, penetrator	Launch failure
Mars Pathfinder	4 December 1996	4 July 1997	27 September 1997	Lander, rover	Success
Nozomi (Planet-B)	3 July 1998		9 December 2003	Orbiter	Complications while on route; Never entered orbit
Mars Climate Orbiter	11 December 1998	23 September 1999	23 September 1999	Orbiter	Crashed on surface due to metric-imperial mix-up
Mars Polar Lander	3 January 1999	3 December 1999	3 December 1999	Lander	Crash-landed on surface due to improper hardware testing
Deep Space 2 (DS2)				Hard landers
Mission (2000–2011+)	Launch	Arrival at Mars	Termination	Elements	Result
2001 Mars Odyssey	7 April 2001	24 October 2001	Currently operational	Orbiter	Success
Mars Express	2 June 2003	25 December 2003	Currently operational	Orbiter	Success
Beagle 2			6 February 2004	Lander	Lost contact in December 2003 after separation from Mars Express. Fate unknown.
MER-A Spirit	10 June 2003	4 January 2004	last contact March 2010, stuck. Contact lost.	Rover	Success
MER-B Opportunity	7 July 2003	25 January 2004	Currently operational	Rover	Success
Rosetta	2 March 2004	February 25, 2007	Currently operational	Gravity assist enroute to comet 67P/Churyumov-Gerasimenko	Success
Mars Reconnaissance Orbiter	12 August 2005	10 March 2006	Currently operational	Orbiter	Success
Phoenix	4 August 2007	25 May 2008	10 November 2008	Lander	Success
Dawn	27 September 2007	17 February 2009	Currently operational	Gravity assist to Vesta	Success
Fobos-Grunt	8 November 2011	September 2012	Currently operational	Orbiter	Launch complications[17]
Yinghuo-1		October 2012		Orbiter	Launch complications[18]

Future missions

Name	Estimated launch	Elements	Notes
MSL Curiosity	Between 25 November and 18 December 2011[19]	Rover	Powered by radioisotopes, it will perform chemical and physical analysis on martian soil and atmosphere.
MetNet	2012–2019	Multi-lander network	Simultaneous meteorological measurements at multiple locations.[20]
MAVEN	2013	Orbiter	Will study Mars' upper atmosphere
ExoMars	2016	Orbiter, static lander	The Trace Gas Orbiter will deliver the ExoMars static lander.
	2018	Rover	ExoMars rover
Mars mission	2013-2015[21]	Orbiter	In the conceptual phase[22][23]
Mars sample return mission	2020s	Orbiter, lander, rover, sample return	Under study; not yet funded or scheduled

Concept missions

There are a number of conceptual missions for the exploration of Mars, but the missions are not yet fully funded nor under development.

'Red Dragon' Mars Mission

As of July 2011^[update], NASA Ames Research Center is developing a concept for a low-cost Mars mission that would utilize a SpaceX Falcon Heavy as the launch vehicle and trans-Martian injection vehicle, and the Dragon capsule to enter the Martian atmosphere. The concept would be proposed for funding in 2012/2013 as a NASA Discovery mission, for launch in 2018 and arrival at Mars several months later. The science objectives of the mission would be to look for evidence of life — detecting "molecules that are proof of life, like DNA or perchlorate reductase ... proof of life through biomolecules. ... Red Dragon would drill 3.3 feet (1.0 m) or so underground, in an effort to sample reservoirs of water ice known to lurk under the red dirt." The mission cost is projected to be less than US$425,000,000, not including the launch cost.^[24]

Cancelled missions

• Mars 4NM and Mars 5NM - projects intended by the Soviet Union for heavy Marsokhod (in 1973 according to initial plan of 1970) and Mars sample return (planned for 1975) missions by launching on N1 rocket that has never flown successfully.^[25]
• Voyager - USA, 1970s - Two orbiters and two landers, launched by a single Saturn V rocket.
• Mars Aerostat - Russian/French balloon mission,^[26] originally planned for the 1992 launch window, postponed to 1994 and then to 1996 before being cancelled.^[27]
• Mars Environmental Survey - set of 16 landers planned for 1999–2009
• Mars-98 - Russian mission including an orbiter, lander, and rover, planned for 1998 launch opportunity
• Mars Surveyor 2001 Lander - October 2001 - Mars lander
• Beagle 3 - 2009 British lander mission meant to search for life, past or present.
• NetLander- 2007 or 2009 - Mars netlanders
• Mars Telecommunications Orbiter - September 2009 - Mars orbiter for telecommunications
• Mars Astrobiology Explorer-Cacher - 2018 rover
• Kitty Hawk - Mars airplane micromission, proposed for December 17, 2003, the centennial of the Wright brother's first flight.^[28] Its funding was eventually given to the 2003 Mars Network project.^[29]

See also

• Atmospheric reentry
• Life on Mars
• List of artificial objects on Mars
• Mars Exploration Joint Initiative
• Mars Scout Program
• Mars to Stay
• New Frontiers Program
• Space colonization
• Space exploration
• Space weather
• Timeline of Solar System exploration
• Jet Propulsion Laboratory Science Division

References

1. ^ Dinerman, Taylor (2004-09-27). "Is the Great Galactic Ghoul losing his appetite?". The space review. http://www.thespacereview.com/article/232/1. Retrieved 2007-03-27. 
2. ^ Knight, Matthew. "Beating the curse of Mars". Science & Space. http://www.cnn.com/2006/TECH/science/12/23/mwonders.mars/index.html. Retrieved 2007-03-27. 
3. ^ "NASA and ESA Establish a Mars Exploration Joint Initiative". NASA. July 8, 2009. http://www.nasa.gov/mission_pages/mars/news/mars-20090708.html. Retrieved 2009-11-09. 
4. ^ "NASA, ESA Set Up Mars Exploration Framework". Aviation Week. July 10, 2009. http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=space&id=news/Mars071009.xml. Retrieved 2009-11-09. 
5. ^ Sheehan, William (1996). "The Planet Mars: A History of Observation and Discovery". The University of Arizona Press, Tucson. http://www.uapress.arizona.edu/onlinebks/mars/contents.htm. Retrieved 2009-02-15. 
6. ^ ("opposition-class trajectory")
7. ^ ISBN 0-8165-1257-4
8. ^ Raeburn, P. 1998. Uncovering the Secrets of the Red Planet Mars. National Geographic Society. Washington D.C.
9. ^ Moore, P. et al. 1990. The Atlas of the Solar System. Mitchell Beazley Publishers NY, NY.
10. ^ Bothwell, William (2008-10-23). "Looking to Mars". Orangeville Citizen. http://www.citizen.on.ca/news/2008/1023/columns/032.html. Retrieved 2008-10-29. 
11. ^ "The Depths of Space: The Story of the Pioneer Planetary Probes (2004)" from The National Academies Press. URL accessed April 7, 2006.
12. ^ "Uncovering the Secrets of Mars" (first paragraph only). Time July 14, 1997 Vol. 150 No. 2. URL accessed April 7, 2006.
13. ^ Matthews, John & Caitlin. "The Element Encyclopedia of Magical Creatures",Barnes & Noble Publishing, 2005. ISBN 0-7607-7885-X
14. ^ The "Mars Curse": Why Have So Many Missions Failed?
15. ^ Lupisella, ML. "Human Mars Mission Contamination Issues." NASA.
16. ^ ^{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.
17. ^ http://www.msnbc.msn.com/id/45208128/ns/technology_and_science-space/
18. ^ http://www.msnbc.msn.com/id/45208128/ns/technology_and_science-space/
19. ^ "Geometry Drives Selection Date for 2011 Mars Launch". News and Features. NASA/JPL-Caltech. http://www.jpl.nasa.gov/news/news.cfm?release=2010-171. 
20. ^ MetNet Mars Mission
21. ^ http://articles.timesofindia.indiatimes.com/2009-08-31/india/28164136_1_chandrayaan-1-indian-deep-space-network-first-moon-mission
22. ^ "ISRO gearing up for Mars mission news". Aviation and Aerospace. August 12, 2009. http://www.domain-b.com/aero/space/spacemissions/20090812_chandrayaan_1_oneView.html. Retrieved 2009-08-20. 
23. ^ "ISRO Eyes Mission To Mars As Government Sanctions Funding". Mars Daily. August 13, 2009. http://www.marsdaily.com/reports/ISRO_Eyes_Mission_To_Mars_As_Government_Sanctions_Funding_999.html. Retrieved 2009-08-20. 
24. ^ Wall, Mike (2011-07-31). "'Red Dragon' Mission Mulled as Cheap Search for Mars Life". SPACE.com. http://www.space.com/12489-nasa-mars-life-private-spaceship-red-dragon.html. Retrieved 2011-07-31. "This so-called "Red Dragon" mission, which could be ready to launch by 2018, would carry a cost of about $400 million or less. ... developing the Red Dragon concept as a potential NASA Discovery mission, a category that stresses exploration on the relative cheap. ... NASA will make another call for Discovery proposals in 18 months or so... If Red Dragon is selected in that round, it could launch toward Mars in 2018. ... Assuming that $425 million cap [for NASA Discovery missions] is still in place, Red Dragon could come in significantly under the bar. We'd have money left over to do some science." 
25. ^ Советский грунт с Марса (Russian)
26. ^ C. Tarrieu, "Status of the Mars 96 Aerostat Development", Paper IAF-93-Q.3.399, 44th Congress of the International Astronautical Federation, 1993.
27. ^ P.B. de Selding, "Planned French Balloon May Be Dropped", Space News, 17–23 April 1995, pp. 1, 20
28. ^ Oliver Morton in To Mars, En Masse, p.1103-04, Science (Magazine) vol 283, 19 february 1999, ISSN 0036-8075
29. ^ MIT Mars Airplane Project

Further reading

• Mars - A Warmer, Wetter Planet by Jeffrey S. Kargel (published July 2004; ISBN 978-1-85233-568-7)
• The Compact NASA Atlas of the Solar System by Ronald Greeley and Raymond Batson (published January 2002; ISBN 0-5218-0633-X)
• Mars: The NASA Mission Reports / edited by Robert Godwin (2000) ISBN 1896522629

External links

• Mars Program by the American JPL
• Mars Rovers' newsroom
• Next on Mars (Bruce Moomaw, Space Daily, 9 March 2005): An extensive overview of NASA's Mars exploration plans
• Catalog of Soviet Mars images Collection of Russian Mars probes' images.
• Mars balloon
• NASA History Series Publications (many of which are on-line)
• Simplified study of orbits to land on Mars and return to Earth High School level.