Kepler and Search for Extrasolar Planets

Recently NASA announced an astounding discovery: The Kepler missions confirmed the first exoplanet orbiting in the habitable zone of a sun-like G-types star. The newly discovered planet Kepler-22b is a little more than double the size of Earth, and it is located 600 light years away. [1] That is a long way to go, but either way, this discovery is a milestone for the Kepler mission and the search for Earthlike planets.

Kepler space observatory launched in 2009 on a mission to scan an area of the Milky Way galaxy between Cygnus and Lyra in search for Earthlike life supporting planets located in habitable zones. [2] The telescope uses the transit method to detect if a planet passes in front of a star and blocks its light for a very short time. So far 2326 possible planet candidates circling over 1000 stars have been detected by Kepler. Of these, 207 have the size of Earth, 680 are much bigger than our planet, 1181 have the size of Neptune, 203 of Jupiter, and 55 are even larger than Jupiter. But more importantly, 48 of them are confirmed to orbit in habitable zones. [3]

Potential life habitats should be abundant in water and carbon, as well as other elements necessary in organic compounds, such as nitrogen. For the water to stay in liquid form, pressure should not be less than 610Pa. Temperature is also crucial: carbon based life can develop in environments with a temperature up to 160°C and down to several tens of degrees bellow 0°C. Habitats can exist either at the surface or below. [4] All these conditions create the so-called habitable zones. The habitable zone is the range of distances from a star within which water occupies large territories and remains in liquid form on the surface of a planet. [5] It is however not enough for a planet to be in the habitable zone to develop life. Volatiles are needed to form an atmosphere. The planet has to have sufficient mass so that the atmosphere could provide pressure for water to stay liquid; it has to be geologically active; its atmosphere should not leak into space. [6]

Some of the planets discovered by Kepler live in a binary system, orbiting two stars (Kepler-16b), some are much larger than Earth (Kepler-11), or much smaller and rocky (Kepler-10b); others live in complex solar systems with more planets (Kepler-18b, c, and d), yet others seem to be almost identical twins of our planet (Kepler-22b). [7] Kepler may be able to confirm that Earth is not that unique after all.

The latest discovery, Kepler-22b has a revolution period of 290 days, it is 2.4 times larger than Earth, and has a temperature of approximately 22°C. [8] It is yet to be discovered if the planet is gaseous or rocky, what is its mass, and if it has an atmosphere or magnetosphere. Since our technology is far from even studying in depth such a planet, let alone to visit it even by robotic missions, the promise of such discoveries is more in terms of revealing that Earthlike planets could have formed in other solar system and therefore could harbor life.

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Notes:

[1] Phillips, Tony.  Kepler Confirms First Planet in Habitable Zone of Sun-like Star. NASA Science News. http://science.nasa.gov/science-news/science-at-nasa/2011/05dec_firstplanet/ (accessed December 12, 2011), para. 1

[2] Ames Research Center. Kepler: Importance of Planet Detection. http://kepler.nasa.gov/Mission/QuickGuide/ (accessed December 12, 2011), para. 1

[3] Phillips, Tony.  Kepler Confirms First Planet in Habitable Zone of Sun-like Star. NASA Science News. http://science.nasa.gov/science-news/science-at-nasa/2011/05dec_firstplanet/ (accessed December 12, 2011), para. 9

[4] Jones, Barrie William. Life in the Solar System and Beyond. Chichester: Praxis Publishing, 2004, 78.

[5] Ibid, 79.

[6] Ibid, 80.

[7] Ames Research Center. Kepler: Discoveries. http://kepler.nasa.gov/Mission/discoveries/ (accessed December 12, 2011), para. 1

[8] Phillips, Tony.  Kepler Confirms First Planet in Habitable Zone of Sun-like Star. NASA Science News. http://science.nasa.gov/science-news/science-at-nasa/2011/05dec_firstplanet/ (accessed December 12, 2011), para. 4.

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References

Ames Research Center. Kepler: Discoveries. http://kepler.nasa.gov/Mission/discoveries/ (accessed December 12, 2011).

Ames Research Center. Kepler: Importance of Planet Detection. http://kepler.nasa.gov/Mission/QuickGuide/ (accessed December 12, 2011).

Jones, Barrie William. Life in the Solar System and Beyond. Chichester: Praxis Publishing, 2004

Phillips, Tony.  Kepler Confirms First Planet in Habitable Zone of Sun-like Star. NASA Science News. http://science.nasa.gov/science-news/science-at-nasa/2011/05dec_firstplanet/ (accessed December 12, 2011).

Image source: NASA/Ames/JPL-Caltech, http://www.nasa.gov/images/content/607691main_Kepler22bArtwork_946-710.jpg

Failures of Robotic Exploration to Mars

Mars is known has a reputation to be the “spacecraft cemetery” because lots of robotic missions to the Red Planet have been lost. Actually, an overwhelming 60 percent (26 of 43) of the probes launched by all space exploration nations to explore Mars have failed. NASA’s results are not far from these either: without taking into consideration the Mars Science Laboratory, which is on the way to Mars and hopefully will succeed, NASA launched 19 missions to the Red Planet, of which seven probes were lost: Mariner 3, Mariner 8, Mars Observer, Mars Climate Orbiter, Mars Polar Lander, and the two Deep Space 2 Probes. [1] What is going on?

Mariner 3, launched in 1964, did not make it to Mars because the shroud on top of the rocket where the probe was located did not open properly, and the solar panels did not open, so the spacecraft ended up orbiting the sun uselessly. [2] Mariner 8 failed during launch in 1971. [3] While the Mars Observer was successfully launched in 1992 and traveled all the way to Mars for 337 days, the contact with the probe was lost in 1993 just when it was about to enter orbit. [4] The Mars Climate Orbiter was launched in 1998 to function as a weather satellite in orbit around Mars, but it was also lost when it arrived to the Red Planet one year later, in 1999. [5] The Mars Polar Lander had as mission to land to the Martian South Pole. Launched in the beginning of 1999 together with the two Deep Space 2 probes, the entire missions with 3 probes on board was lost, again at their arrival to the Red Planet, at the end of 1999. [6]

Is there a Mars curse going on? One reason more probes are lost to Mars than any other celestial body is that more missions were launched to explore the Red Planet than any other body in the solar system. But there is also human error. Such an error occurred during inserting the Mars Climate Orbiter into orbit: because of a navigational error, the satellite occupied an orbit 100 kilometers lower than it was initially intended. The error was performed by NASA’s subcontractors, Lockheed Martin simply because they were not using the standard metric system, which in turn led to serious calculation errors. [7]

It is also important to notice that most failures have occurred in the early years of space exploration, and each of them helped improve the next mission. I would rather give some credit to the Red Planet than blame it for those missions that did not make it, by labeling such results as being a consequence of a Mars curse. It may also seem not to be the right approach to look into failures rather than successes, but I am a firm believer that we learn from the failed missions much more than we learn from the successful ones. Sending robotic explorers to Mars is a complex business, and the recently extremely successful missions to the Red Planet owe a lot to those that did not make it.

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Notes:
[1] National Aeronautics and Space Administration. Mars Exploration Program: Historical Log. http://mars.jpl.nasa.gov/programmissions/missions/log/ (accessed December 5, 2011), p. 1.

[2] NASA. Mars: NASA Explores the Red Planet, Mariner 3 and 4. http://www.nasa.gov/mission_pages/mars/missions/mariner3-4-index.html (accessed December 5, 2011), para. 2.

[3] NASA. Mars: NASA Explores the Red Planet, Mariner 8 and 9. http://www.nasa.gov/mission_pages/mars/missions/mariner8-9-index.html (accessed December 5, 2011), para. 2.

[4] NASA. Mars: NASA Explores the Red Planet. http://www.nasa.gov/mission_pages/mars/missions/index-past.html (accessed December 5, 2011).

[5] Ibid.

[6] Ibid.

[7] O'Neill, Ian. The “Mars Curse”: Why Have So Many Missions Failed? Universe Today, March 22, 2008. http://www.universetoday.com/13267/the-mars-curse-why-have-so-many-missions-failed/ (accessed December 5, 2011), para. 9.

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References

NASA. Mars: NASA Explores the Red Planet. http://www.nasa.gov/mission_pages/mars/missions/index-past.html (accessed December 5, 2011).

NASA. Mars: NASA Explores the Red Planet, Mariner 3 and 4. http://www.nasa.gov/mission_pages/mars/missions/mariner3-4-index.html (accessed December 5, 2011).

NASA. Mars: NASA Explores the Red Planet, Mariner 8 and 9. http://www.nasa.gov/mission_pages/mars/missions/mariner8-9-index.html (accessed December 5, 2011).

National Aeronautics and Space Administration. Mars Exploration Program: Historical Log. http://mars.jpl.nasa.gov/programmissions/missions/log/ (accessed December 5, 2011).

O'Neill, Ian. The “Mars Curse”: Why Have So Many Missions Failed? Universe Today, March 22, 2008. http://www.universetoday.com/13267/the-mars-curse-why-have-so-many-missions-failed/ (accessed December 5, 2011).

Science Fiction - Science Fact

I have never been a science fiction fan, and I am not familiar with many examples. Therefore the ones I have chosen may belong to common knowledge. For a science fiction thing that is already a science fact, I chose man’s trip to the moon, as illustrated by Jules Verne and transformed into a science fact by the Apollo program. For a science fiction thing that is still to become a science fact, but it may sometime soon, I chose extraterrestrial life.

In 1865 Jules Verne published From the Earth to the Moon. In this story, to reach the moon, the characters launch themselves from a canon in a projectile spaceship to land on the Moon. Since the novel does not conclude as to what happened to the characters afterwards, Jules Verne wrote a sequel entitled Around the Moon in which the author continues to follow the unfinished trip to the moon. I believe the idea that man could travel to the moon developed in this book has generated lots of confidence in people that such a thing could become a possibility. After all, Jules Verne’s literature brought some other ideas that later on became reality, such as the submarine in Twenty Thousand Leagues under the Sea, and the helicopter in Robur the Conqueror. A book like From the Earth to the Moon could have had an impact on the eventual development of space travel to the moon. Actually, during the return trip to Earth of Apollo 11, Neil Armstrong said:

"A hundred years ago, Jules Verne wrote a book about a voyage to the Moon. His spaceship, Columbia took off from Florida and landed in the Pacific Ocean after completing a trip to the Moon. It seems appropriate to us to share with you some of the reflections of the crew as the modern-day Columbia completes its rendezvous with the planet Earth and the same Pacific Ocean tomorrow." [1]

The Day the Earth Stood Still is probably one of the very few science fiction stories that captured my interest. At the beginning of this story, an astrobiologist is recruited by the government to participate in a highly classified operation that turns out to be the landing of an extraterrestrial spaceship in the Central Park of New York. I believe we are getting close to discover life elsewhere in the universe. While I am not convinced the reality will occur just like in The Day the Earth Stood Still, as intelligent life seems to be scarce, simple life forms have a good chance to thrive on various other celestial bodies. Earth’s extremophiles have proved that life can develop about anywhere, in any kind of environment. With this knowledge in mind, we will have to design future missions capable to reveal such a possibility. While Curiosity is on the way to forever change our views about the neighbor planet, missions like the Europa Jupiter System Mission seem realistic and possible in the next decade. Such a mission would search Europa’s surface for evidence of fossilized organisms that have been carried up through the cracks and deposited on the surface. This would be sufficient to reveal life on Europa, provided its already discovered liquid ocean has been harboring life for quite while. This seems to be a science fiction scenario about to become science fact, and I sure hope this will happen in my lifetime. 

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Notes:

[1] NASA History. Apollo Flight Journal, Apollo 11, Day 8, part 2: More Television and Stowage for Re-entry. http://history.nasa.gov/ap11fj/25day8-reentry-stowage.htm (accessed November 28, 2011).

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Reference

NASA History. Apollo Flight Journal, Apollo 11, Day 8, part 2: More Television and Stowage for Re-entry. http://history.nasa.gov/ap11fj/25day8-reentry-stowage.htm (accessed November 28, 2011).

Humans and Robots II

I first realized I had an opinion about whether humans or robots should explore space was when the Obama Administration cancelled the Constellation program. I realized then, and no offense to anyone whose job was affected by this decision, that it was appropriate to put the breaks on the human spaceflight program until further progress was made in the field, and that exploring the solar system with probes is the perfect solution for now. Even at that time I was not for exclusive exploration with robots, but rather for using machines in places where humans cannot yet go in preparation for when they will eventually be ready for deep space travel.

The main reason I was completely dedicated the robotic exploration was the outstanding discoveries that our probes have brought in the past two decades. We have learned so much about our neighborhood, and we have discovered for the first time the real vastness of the universe and many of its secrets. While our presence in the solar system is still scarce, with the very few probes that visited Mars, Jupiter and Saturn we came very close to realizing the potential of life all over the place. Just couple of days ago the existence of a liquid water ocean on Europa has been confirmed from the analysis of data sent by Galileo. Not to mention how the Hubble Telescope has completely changed our perspective about the universe. “The greatest explorer today is not even human. It’s the Hubble Space Telescope, which for nearly two decades has offered us all a mind-expanding window to the cosmos”. [1]

But I am a firm believer human should explore space by themselves and not completely rely on robots. “Exploration is inherent to humankind… and it makes us human”. [2] Thirst for knowledge is one of the main characteristics of the species. Space exploration is a process expanding the human knowledge and its range of action. [3] Human space flight has both and immediate and long-term importance. Direct exploration offers closer insights, familiarizing the human species with living in space, and it is likely to provide further survival on other celestial bodies when planet Earth will be no longer suited for human habitation.

Reading chapter 3 in Robots in Space did not really change my ideas, but made me think further about the mid-20^th century when enthusiastic individuals set the foundation of the space age. In the Disney movie Man and the Moon, a whole section is dedicated to Werner von Braun’s fascinating ideas about how man could reach the moon. While watching his presentation I observed myself sliding towards a feeling that this video was recent, and not at all belonging to the fifties. Von Braun’s ideas sounded as if they were taken from Star Trek. I later read in chapter 3 that one reason his fantastic space station could not be accomplished was the discovery of the Van Allen radiation belts. No reason to blame Van Allen for his strong advocacy against human spaceflight after all J But indeed, if I were living in the fifties and watch Von Braun’s presentation I would have not even consider robots. His space station looked more like a building in the city center, having all departments needed to run the show, including gravitation. No wonder such a fantastic idea had a strong impact on the humans vs. robots debate at the beginning of the space age. Who needs robots when humans could live in space just as well as on Earth?

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Notes

[1] Tyson, Neil deGrasse. “Why America Needs to Explore Space”. Parade Magazine. August 5, 2007. http://www.haydenplanetarium.org/tyson/read/2007/08/05/why-america-needs-to-explore-space (accessed November 22, 2011), para. 10.

[2] Dordain, Jean-Jacques. “Space exploration in the 21st Century: Global opportunities and challenges”. http://www.nasa.gov/offices/oce/appel/ask/issues/38/38i_space.html (accessed November 22, 2011), 2.

[3] Ibid, 2.

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References

Dordain, Jean-Jacques. “Space exploration in the 21st Century: Global opportunities and challenges”. NASA Project Management Challenge 9 Feb 2010. http://www.nasa.gov/offices/oce/appel/ask/issues/38/38i_space.html (accessed November 22, 2011)

Tyson, Neil deGrasse. “Why America Needs to Explore Space”. Parade Magazine. August 5, 2007. http://www.haydenplanetarium.org/tyson/read/2007/08/05/why-america-needs-to-explore-space (accessed November 22, 2011).

Image source: http://www.lns.cornell.edu/~seb/celestia/b-vb/images/across_03.jpg

Video Source:  http://www.youtube.com/watch?v=J1urigkMtAw&feature=related

Human & Robotic Spaceflight

While space exploration has been successful both with humans and robots, opinions about whether to continue one, the other, or both are divided. Some people advocate the continuation of human spaceflight, while others consider that robotic exploration will bear fruit in areas where humans cannot go. Such opinions were recently expressed by Michael D. Griffin, NASA administrator, and John Merchant, CEO of the robotics firm RPU Technology.

“I am an unabashed supporter of space exploration in general and of human space flight in particular. I believe that the human space flight program is in the long run possibly the most significant activity in which our nation is engaged. For what, today, do we recall renaissance Spain, King Ferdinand, and Queen Isabella? Unless one is a professional historian, the memory which is evoked is their sponsorship of Columbus in his voyages of discovery. For what, in five hundred years, will our era be recalled? We will never know, but I believe it will be for the Apollo lunar landings if for anything at all. And this is entirely appropriate. Human expansion into space is a continuation of the ancient human imperative to explore, to exploit, to settle new territory when and as it becomes possible to do so. This imperative will surely be satisfied, by others if not by us.” -Michael D. Griffin

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Griffin is a strong believer that human spaceflight is the most “significant activity” people can engage into and the only one that will be remembered a few centuries from now. He compares the Apollo program to the missions of discovery during the Renaissance and underlines that in 500 years from now the future generations will refer to the lunar landings in the same way we refer to Columbus’ landing in America. Griffin believes that humans are prone to explore and if the US will not do it, other people will. [1]

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"Putting more money into human spaceflight is going to be extremely unproductive. ...My position is that we shouldn’t give up on the human exploration of space, but we recognize that you can perform the human exploration of space by telepresence. ... we’ve already sent two rovers to Mars using early-stage telepresence to dig into the surface of Mars to look for signs of water. I very strongly feel that if we devoted a fraction of the resources that we’ve been devoting to manned spaceflight missions to telepresence, we could develop a capability so that humans on Earth could experience and function in a distant space environment like Mars as effectively as if they were actually there." -John Merchant

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By contrast, Merchant underlines that continuing to pay for human spaceflight would be a big loss. His belief is that robotic exploration can do what people do and even more, and therefore allocating at least some of the manned spaceflight funds to the robotic missions would allow exploration in hostile environments as if people were there, while remaining on Earth. Merchant exemplifies his beliefs with the successful mission of the Mars rovers able to explore the planet without humans. [2]

According to Launius and McCurdy, the prospect of NASA is that robots and humans should work together for further exploration of space. [3] This perspective seems to be right because it includes everybody’s opinion and it is a productive solution. While Griffin might remain disturbed that robots will still be sent to explore the solar system, and Merchant would still believe it is a waste of money to continue sending humans in space, continuing exploration with both sustains both military and civil space programs. [4]

One interesting idea brought up by Launius and McCurdy is that at the moment human capabilities still exceed those of the robots, but on the other hand robots are cheaper and if lost during the mission no human life is at risk. [5] From Griffin’s point of view, praising human capabilities in space would go hand in hand with his idea of human spaceflight as a necessity if we would like to be remembered by the future generation. In the same time, for Merchant, the fact that machines are cheaper and human risk-free would be just the right concept underlining his belief that robots deserve some of the human spaceflight’s funds so that they can do more than people.

One of the reasons for such different opinions may lay in the fact that individuals engaged in the humans vs. robots debates consider the two to be completely different things with separate visions. The idea advocated by Launius and McCurdy that humans and machines are not “separate entities” may come as a surprise for both Griffin and Merchant. Humans and robots do the same kind of work, while complementing each other rather than taking each other’s place. [6] Having both may be the best solution. While Griffin’s reaction to these arguments may still gravitated around finances and the waste of money invested in human space flight, Merchant’s reaction may also be that robots can do better in places where humans cannot go. Either way, the idea that Griffin and Merchant could pick from Robots in Space is that having humans or robots explorers does not need to be a debate, but rather cooperation.

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Notes:

[1] SpaceRef. Prepared Statement of Dr. Michael D. Griffin: "The Future of Human Space Flight". October 16, 2003. http://www.spaceref.com/news/viewsr.html?pid=10683 (Accessed November 8, 2011), para. 3.

[2] Berger, Eric. The case for sending robots, not humans, to Mars. August 19, 2009. http://blog.chron.com/sciguy/2009/08/the-case-for-sending-robots-not-humans-to-mars/ (Accessed November 8, 2011), para. 4-5.

[3] Launius, Roger D. and Howard E. McCurdy. Robots in Space. Baltimore: Johns Hopkins University Press, 2008, 27.

[4] Ibid, 27.

[5] Ibid, 3.

[6] Ibid, 30.

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References

Berger, Eric. The case for sending robots, not humans, to Mars. August 19, 2009. http://blog.chron.com/sciguy/2009/08/the-case-for-sending-robots-not-humans-to-mars/ (Accessed November 8, 2011).

Launius, Roger D. and Howard E. McCurdy. Robots in Space. Baltimore: Johns Hopkins University Press, 2008.

SpaceRef. Prepared Statement of Dr. Michael D. Griffin: "The Future of Human Space Flight". October 16, 2003. http://www.spaceref.com/news/viewsr.html?pid=10683 (Accessed November 8, 2011).

Image source: http://www.airspacemag.com/space-exploration/Humans_vs_Robots.html

Life in the Solar System - Enceladus

While Voyager 2 was able to provide just low resolution images of Enceladus, stirring up interest, the Cassini mission has revealed that this moon of Saturn is still very active geologically, with geysers shooting water vapors hundreds of miles into the air, similar to the geysers in Yellowstone. Saturn’s gravity creates frictional heat, generating the evaporation of the water ice on Enceladus, creating the geysers. The gases coming through the surface are made of carbon and nitrogen, all sufficient to sustain primitive life. Organic compounds and possibly underground channels of water seem to fulfill the requisites for life. [1] On Earth, microorganisms consuming hydrogen and carbon dioxide, and releasing methane thrive in subsurface volcanic strata where liquid water is present, and take their energy from the planet’s internal heat. Therefore Enceladus seems to be the holy grail of the search for life. [2]

Whether habitable by human understanding or not, exploring only a few celestial bodies in the solar system can forever change human belief about life in the universe. Life could be everywhere, from microorganisms living beneath the surface of Mars and in thermal vents on Enceladus, and creatures developed around other element than carbon that may be living in the methane lakes of Titan, to possibly more complex life forms living in the oceans hidden beneath the surface of Europa. One could be pessimistic and claim that since no life has been seen anywhere else, it is likely that it does not exist. However, the scientists must stay optimistic, as the scientific method requires a hypothesis so that any idea could develop further. Hypothesizing that life may be present on these celestial bodies has at least generated research benefic for the understanding of life’s origin on Earth.

Life may be everywhere, but it is also possible that no evidence of life will turn up. However, if life can come into existence as easily as it seems to have taken shape on Earth, it has to also develop in some other corners of the solar system. Either way, the search for life will provide the ultimate insight into whether life is rare or widespread, and this will be a decisive point in human understanding of the universe.

Notes

[1] Porco, Carolyn. "The Restless World of Enceladus. (Cover story)." Scientific American 299, no. 6 (December 2008): 52-63. Academic Search Premier, EBSCOhost (accessed October 12, 2011), 52.

2 Ibid, 63.

Life in the Solar System - Titan

One step further in the solar system lays Saturn, and its largest moon Titan seems to be one of the most serious candidates for life, however not a carbon based life. While recent images of this moon have revealed a celestial body that looks very much like Earth, the chemical composition of these features is quite different. Titan seems to be more like an early Earth. It has a thick atmosphere, with oceans and mountains, winds, river channels, dunes, as well as weather cycles and volcanism. The atmosphere on Titan is thick, hazy, and similar to Earth’s early atmosphere, composed of 90 percent nitrogen, as well as argon, methane and ethane. No oxygen means there is no water vapor, ozone or carbon dioxide. However there are greenhouse gases: methane and ethane. The methane condenses, forming clouds and methane rain. The lakes on this moon are made of liquid methane. Sunlight converts methane into ethane, generating organic compound. But it is cold on Titan: -180°C, and the atmospheric pressure on the surface is 50 percent greater than on Earth. [1] Titan is the only moon other than Earth’s to have been explored. In January 2005, the unmanned Huygens probe launched by the Cassini mission descended onto Titan’s surface. Recent studies from the Huygens probe suggest that there is hydrogen and acetylene on the surface of Titan, which could serve as nutrients for methanogens even in cold environments, and therefore the presence of primitive life on the surface of Titan is possible. [2] The chemistry of Titan looks hostile to carbon based life, but back on Earth psychrophiles thrive in extreme cold environments and use methane to produce energy. Either way, the resemblance to an early Earth and the complicated chemical processes on Titan are an excellent source of understanding prebiotic processes. [3]

Life in the Solar System - Europa

Since life in the habitable zone did not yet reveal itself, the search has moved further in the solar system to reach the Jovian planets. While life on the gas giants seems unlikely, the Galileo mission to Jupiter has disclosed that its moons are a whole different topic, and Europa holds the gold medal as far as life is concerned, mainly because liquid water seems to be abundant on this tiny moon. Europa presents itself to be a fascinating world. If there is complex life anywhere else in the solar system, it would be here. The moon is covered by an icy, young crust, almost crater-free, denoting that Europa’s surface is active, and craters must have flattened out by the warmth beneath. [1] The moon has no magnetic field, hence no melted inner core. But there is definitely tidal heat, and therefore geological activity, and interaction with Jupiter’s magnetosphere, revealing that the layer under the thick icy crust might as well be a liquid water sea with warm thermal vents at the bottom of the ocean. [2] On Earth life already thrives in warm thermal vents on the ocean floor. Images of Europa taken by Galileo have also revealed volcanic activity that would generate the chemicals necessary for life.

Europa is the main candidate for complex life forms. As Neil deGrasse Tyson points out enthusiastically, “I want to go ice-fishing on Europa, cut a hole, put a submersible, look around, see if anything swims up to the camera lens and looks at the camera”. [3] But a mission capable of digging through the thick icy crust seems ambitious at the moment. A hydrobot is being built in Austin, Texas - the Deep Phreatic Thermal Explorer (DepthX). [4] If DepthX proves itself successful in exploring Earth’s oceans, it may become a viable solution for a mission to Europa. For now, the Europa Jupiter System Mission seems more realistic, as it would search the surface for evidence of fossilized organisms that have been carried up through the cracks and deposited on the surface. Such a mission would be sufficient to reveal life on this moon. Europa Jupiter System Mission is at the moment only a concept planned to launch around 2020 with an orbiter on board. [5]

Notes

[1] Pappalardo, Robert T., James W. Head, and Ronald Greeley. "The Hidden Ocean of EUROPA." Scientific American Special Edition 13, no. 3 (September 2, 2003): 64-73. Academic Search Premier, EBSCOhost (accessed October 11, 2011), 56.

2 Seeds, Michael. The Solar System. Boston: Brooks/Cole, Cengage Learning, 2011, 594.

3 The Universe: Jupiter, directed by Andrew Nock (2007; The History Channel). DVD.

4 Deep Phreatic Thermal Explorer Project. About the DepthX Project. http://www.frc.ri.cmu.edu/depthx/about.html (Accessed October 11, 2011).

5 Lawler, Andrew. "Is This the Best Place to Find Life in the Solar System?." Discover 30, no. 8 (September 2009): 42-47. Academic Search Premier, EBSCOhost (accessed October 11, 2011), 2.

Life in the Solar System - Mars

The fascination with Mars and its habitability has been going on for centuries. And indeed, Mars holds the greatest life potential of all the other planets, since water seems to have been flowing on its surface in the past. The flyby of Mariner 4 in July 1965 has forever changed the hopes that Mars was inhabited by intelligent beings. Mariner 4 revealed a dry planet with a small mass, while the Viking landers confirmed that there was no sign of life on Mars’ surface. [1] The Martian landscape revealed by probes is a witness of a geological active past. On Earth, plate tectonics was essential in promoting biodiversity and defense against mass extinctions. A geological active Red Planet could have been a good habitat for life. In the same time, the Mars Reconnaissance Orbiter has revealed the possibility that salty water could flow on the surface during the Martian summer. Frozen water has been detected in middle to high-latitude regions of the planet. [2]

The Martian surface seems lifeless, static, inhospitable, cold, dry, and desolate. Mars is about half the size of Earth and has lower gravity and pressure. Temperature goes down to 100°C bellow zero every night, and the atmosphere has no oxygen, but it is composed almost entirely of carbon dioxide. Liquid water would freeze and evaporate in the same time on the surface. The Red Planet has lost its magnetic field and atmosphere, and the liquid water disappeared from the surface.  Huge dust storms darken its sky for weeks or months. [3] If life has survived here, it must be hidden below the surface where water may still be liquid.

A recent discovery has revealed that Mars’ atmosphere contains light traces of methane. Methane is abundant on Earth, and 90 to 95 percent of it has biological sources. [4] Since ultraviolet radiation on Mars would destroy the methane, the gas must have been recently produced. Geological activity could also be a source, but methane was discovered in areas where there are no volcanoes. The presence of this gas in Mars’ atmosphere could originate from microorganisms living beneath the surface. [5] However, hard proof evidence may only be available when humans will reach Mars. Until then, scientists rely on the rovers Spirit and Opportunity to discover any traces of life on the neighboring planet. While Spirit has been silent since March 2010, Opportunity is still active. The Mars Science Laboratory, nicknamed Curiosity, launching in November 2011 and scheduled to land in August 2012, has as main mission to search for past and present biological activity.

Notes:

[1] Jones, Barrie William. The Search for Life Continued. Chichester: Praxis Publishing, 2008, 78.

2 Webster, Guy, Cole, Steve, Stolte, Daniel. NASA Spacecraft Data Suggest Water Flowing on Mars. NASA, Aug.4, 2011. http://www.nasa.gov/mission_pages/MRO/news/mro20110804.html (accessed October 11, 2011), 1.

3 Webster, Guy, Cole, Steve, Stolte, Daniel. NASA Spacecraft Data Suggest Water Flowing on Mars. NASA, Aug.4, 2011. http://www.nasa.gov/mission_pages/MRO/news/mro20110804.html (accessed October 11, 2011), 79.

4 Atreya, Sushil K. "The Mystery of Methane on Mars & Titan. (Cover story)." Scientific American 296, no. 5 (May 2007): 42-51. Academic Search Premier, EBSCOhost (accessed October 11, 2011), 42.

5 Seeds, Michael. The Solar System. Boston: Brooks/Cole, Cengage Learning, 2011, 594.

Life in the Solar System - Overview

For millennia, people looked at the sky and wondered about its mysteries. Observing celestial phenomena is a constant that unifies humanity throughout space and time. People followed the movements of the planets and the perpetual change of the constellations. They learned to read their changing patterns, and used them for navigation, agriculture, and warfare. The human hunger for exploration developed further, and man reached the surface of the moon. The search for life elsewhere sprung from a sudden cosmic loneliness that humanity experienced, and hence the question “are we alone?” From looking at the sky to probing other planets with robots, humanity is trying to decipher one of the biggest mysteries known to man. Taking into account the vastness of the universe, searching for life in the neighborhood would be the first step. But where in the solar system should explorers search for life, and what exactly to look for? To gain insight into where and how life could have happened, exploration begins with the only known example: life on Earth. Since Earth seems to be unique, life appears to be sparse. However, life on Earth is abundant and present in extreme environments, therefore it could have developed everywhere else in the universe. This paper provides an overview of the origins of life on Earth and its success in extreme environments as a possible suggestion that life could have developed elsewhere in the solar system, as well as a short research of plausible life on Mars, Europa, Titan and Enceladus.

Life on Earth started four billion years ago, as soon as the conditions on the planet became slightly favorable to ignite the spark of life. Favorable conditions allowed life to become firmly rooted in less than half a billion years. [1] To figure out how this happened and how did non-living matter turn into life, biologists imagined the process of evolution in reverse. Reversing evolution concluded that life on Earth started in simple forms, such as carbon-chained molecules capable of copying themselves. [2] These organisms did not have any bones or shell that could have been fossilized and preserved, and the evidence of their existence is scarce. However, ancient rocks dating over three billion years ago have revealed stromatolites, fossilized colonies of these single cell organisms. Life was thriving in oceans just a billion years after its beginnings. [3]

But what exactly is life? While there is no clear definition, one way of referring to life is by what living organisms do. Life is the process of extracting energy from the surrounding environment in order to maintain and reproduce an organism. [4] All life forms on Earth are carbon based and use water as a solvent. The cell is the basic unit of all living, the ambience in which the processes of life occur. Water is essential for the cell’s proper functioning. Liquid water acts as a solvent for various substances, enabling their transportation inside and between the cells, and it is an active participant in biochemical reactions. [5] Carbon is the best element for formic complex molecules. About all life’s biochemicals are compounds of carbon. Carbon in composition with other elements forms proteins, which have structural, transport, storage, and catalytic functions. The essence of protein synthesis is the RNA and DNA, complex organic compounds playing a role in the process by which organisms reproduce themselves. [6]  

Life on Earth has also developed in extreme conditions. Hyperthermophiles live at high temperatures, between 80–121°C, in the high pressure environment of the ocean floor. Psychrophiles live in low temperatures of about -18°C in the deep oceans, glaciers, polar ice and snowfields. Halophiles live in salinities from 15 to 37.5 percent, alkalophiles live in the alkaline environment of soda lakes and chalky soils, and acidophiles are happy in environments with a pH close to that of vinegar. Some extremophiles can even live in level of radiation lethal to other species. [7] All these organisms are proof that life occurs wherever carbon and liquid water exist.

Having such a successful recipe for life on this planet, the search for life in the cosmic neighborhood starts with looking for the same ingredients: carbon compounds and liquid water. Potential habitats should be abundant in water and carbon, as well as other elements necessary in organic compounds, such as nitrogen. For the water to stay in liquid form, pressure should not be less than 610Pa. Temperature is also crucial: carbon based life can develop in environments with a temperature up to 160°C and down to several tens of degrees bellow 0°C. Habitats can exist either at the surface or below. [8] All these conditions create the so-called habitable zones.

The habitable zone is the range of distances from a star within which water occupies large territories and remains in liquid form on the surface of a planet. [9] It is however not enough for a planet to be in the habitable zone to develop life. Volatiles are needed to form an atmosphere. The planet has to have sufficient mass so that the atmosphere could provide pressure for water to stay liquid; it has to be geologically active; its atmosphere should not leak into space. [10] While Earth has been in the habitable zone throughout its history, Venus has lost its place, and Mars is at the outer boundary.

Water is an abundant substance in the solar system, whether in gaseous or solid form. However life requires liquid water. NASA's Mars Global Surveyor has revealed that some crater walls and hillsides on Mars seem to have formed recently, and liquid water below the surface could have burst out and created the landscape before evaporating. [11] Below surface liquid water is likely to be present also in the outer solar system. Ganymede and Callisto might have oceans trapped between two layers of ice, while Europa is believed to have oceans bellow its ice crust. [12] There seems to be liquid water in the solar system.

The key ingredients essential for life are nutrients and other elements needed for metabolism and reproduction, energy sources (sunlight, chemical reactions, internal heat), liquid water (or other liquid), catalysts such as enzyme proteins, and a stable environment. But life could exist beyond the classical habitable zone. Other habitats could be favorable for different life forms that would revolve around a different element than carbon. Some science fiction stories feature silicon-based life. Silicon belongs to the Group IV of the Periodic Table, together with carbon, and shares many characteristics: both have valence of four, bond to oxygen, form long chains (polymers), alternating with oxygen. However, carbon oxidizes into a gas (carbon dioxide), while silicon into a solid (silicon dioxide). Unlike carbon, silicon does not form many compounds that have handedness, and therefore it would be difficult for such a life form to achieve the functions that carbon-based enzymes perform. The chemistries of life do not seem possible in silicon. [13]

However, arsenic-based life forms have been discovered on Earth: the bacterium GFAJ-1 uses arsenic in its chemical building blocks. Marine algae were found that form organic molecules by incorporating arsenic. [14] Life obviously thrives in environments previously thought to be too harsh, and there is more than one chemical solution to the existence of life. Chlorine and sulfur, as well as nitrogen and phosphorus are also possible replacements for carbon. [15] Since carbon based life has proved to be successful, the search for life must start in the areas where such life forms may be possible. Mars is a candidate.

Where are we headed?

There seem to be two perspectives on the cancellation of the Constellations program, and major participants in previous space programs are divided between the two sides of the barricade. Manned spaceflight is important and giving up on it would be indeed a mistake. However, it did not seem to me at all that this would be the plan of the Obama Administration. 

President Obama’s speech at the Kennedy Space Center was quite inspiring and promising. The President offered an increase in NASA’s funding in order to support robotic exploration which is equally important to the manned spaceflight. Indeed, investing in research that will improve future manned missions seems to be appropriate. [1]. In his speech, President Obama clearly stated the near future objectives of the space program and underlined the importance of stepping forward and doing what NASA has not done before. The proposal seems to be an excellent plan that will support future human endeavors further into deep space, such as landing on asteroids and eventually on Mars.

“…extend the life of the International Space Station likely by more than five years, … conducting advanced research that can help improve the daily lives of people here on Earth, as well as testing and improving upon our capabilities in space. … more efficient life support systems that will help reduce the cost of future missions…” [2]

The Augustine Commission analyzed the situation of the space program in order to offer suggestions on improvements, as well as alternatives, mainly in the light of the termination of the space shuttle program, as well as of the international space station which was supposed to end its operations in 2010. [3] According to the committee, the human spaceflight “appears to be on an unattainable trajectory”. [4] Among the concerns mentioned in the report are matching the space program with the resources, assuring safety, assuring the US keeps its position as global leader in space exploration, as well as moving forward by going further than the LEO and the moon and exploring areas that haven’t been explored before. [5] The Augustine Commission also suggested that in planning the future of the manned spaceflight, goals must be considered first, and destinations should derive from these goals, an excellent idea if we consider that humanity’s main goal with space exploration should be colonizing other celestial bodies and living in space for unlimited time. Ultimately, the conclusion of the committee was that the goal of human spaceflight should be to “chart a path for human expansion into the solar system”. [6]

My belief on the matter is that we should probably look at why we are exploring space in the first place. The motives seem to have changed since the 1960s and 1970s. There is no more space race and the need for military reconnaissance like before. The US does not need to reach first anywhere, but rather improve what has already been done. Most likely the priorities for a space program are of scientific importance. The human race must learn to colonize space in order to assure its future existence. In President Obama’s words, “our goal is the capacity for people to work and learn and operate and live safely beyond the Earth for extended periods of time”. [7] It is appropriate to start focusing on actions that would allow such future endeavors, and for that matter, the future of spaceflight seems promising. I find focusing on such goals to be an excellent strategy.

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Notes:

[1] The White House. Remarks by the President on Space Exploration in the 21st Century. John F. Kennedy Space Center, Merritt Island, Florida. April 15, 2010. http://www.whitehouse.gov/the-press-office/remarks-president-space-exploration-21st-century (Accessed October 26, 2011), 2.

[2] Ibid, 2.

[3] Augustine Commission. 2009. Seeking a Human Spaceflight Program Worthy of a Great Nation. Review of U.S. Human Spaceflight Plans Committee.http://www.nasa.gov/pdf/396093main_HSF_Cmte_FinalReport.pdf (Accessed October 26, 2011), 7.

[4] Ibid, 9.

[5] Ibid, 9.

[6] Ibid, 9.

[7] The White House. Remarks by the President on Space Exploration in the 21st Century. John F. Kennedy Space Center, Merritt Island, Florida. April 15, 2010. http://www.whitehouse.gov/the-press-office/remarks-president-space-exploration-21st-century (Accessed October 26, 2011), 4.

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References

Augustine Commission. 2009. Seeking a Human Spaceflight Program Worthy of a Great Nation. Review of U.S. Human Spaceflight Plans Committee. http://www.nasa.gov/pdf/396093main_HSF_Cmte_FinalReport.pdf (Accessed October 26, 2011).

The White House. Remarks by the President on Space Exploration in the 21st Century. John F. Kennedy Space Center, Merritt Island, Florida. April 15, 2010. http://www.whitehouse.gov/the-press-office/remarks-president-space-exploration-21st-century (Accessed October 26, 2011).

Moon Treaty - Two Issues

Two of the issues that caused the Moon Treaty to be so much more contentious than the Outer Space Treaty are: the use of the term "common heritage of mankind", and the protection of the environment of the Moon. [1]

Article 11 of the Moon Treaty stirred up controversy around the sentence “the moon and its natural resources are the common heritage of mankind…” [2], mainly because the term "common heritage of mankind" is not defined in the treaty. According to Berryhill, such unclarity leads to interpretations derived from political, economic or legal predispositions. [3] One such worry is that the less developed countries unable to participate in space exploration could use this term to benefit of a future distribution of resources. [4] However, it is important to keep in mind the frame in which the Moon Treaty was developed. It was the time when humans barely touched the Moon and euphoria was dominating the human spirit. It was a time when the less developed countries had a chance to have their voice heard. Such a situation dominated the debates at the UN, mainly because these countries together had a strong voice, unlike the countries involved in space exploration at the time. [5]

The definition of the term "common heritage of mankind” implies the possession of all humans, but that also means that "all humans", or mankind should be considered an individual invested with property rights, subject of international law. [6] However, states had different opinions on this matter. USSR expressed that individual property rights are out of the question, and therefore by individual in this case one must understand state or country. Argentina favored less developed countries and their participation in equal sharing of the resources. [7] Hungary pointed that even if mankind is not clearly defined, it exists and should benefit from a common heritage. The United States preferred to focus on the debate over the term "common heritage" than discussing whether mankind is subject to the international law. [8] One of the issues brought up was that by focusing on the idea of common heritage of mankind, exploration and exploitation were linked together [9], generating an interest for profit rather than scientific development.

Another controversy is the environmental protection of the Moon and its resources, especially as mentioned above, the term "common heritage of mankind" implies the full and shared access of all states to the lunar resources. Article 4 of the Moon Treaty emphasizes that any exploration of the Moon has to consider the interest of the future generations. [10] In this spirit, Article 7 calls the explorers to “prevent the disruption of the existing balance of its [the moon’s] environment”. [11]  Unfortunately, the environment protection offered by the language of the treaty is limited, by only specifying  the avoidance of harmful contamination, without underlining what would be the circumstances of this stipulation. [12] In the meantime, terms like "harmful contamination" can be interpreted. One explanation for this lack of clarity is the fact that the Moon's environment was still unknown at the time the treaty was debated, and therefore it would have been hard to express clearly what is it that needs protection. [13] It is also important to bear in mind that exploration will inevitably somehow disturb the environment of the Moon, but articles 6 and 8 of the Moon treaty allow exploration for scientific purposes, such as collecting samples or land a spacecraft on the surface, actions that are not considered harmful. [14]

As space exploration develops, a treaty such as the Moon Treaty will probably need revision in accordance with the new developments in the field. So far, the treaty has worked as a mean to offer the entire mankind a chance to benefit from Moon exploration.

Notes:

[1] Berryhill, Katie J. 1996. The Moon Treaty: A Survey of Selected Legal Issues, 1.

[2] Ibid, 3.

[3] Ibid, 3.

[4] Ibid, 4.

[5] Ibid, 6.

[6] Ibid, 7.

[7] Ibid, 8.

[8] Ibid, 9.

[9] Ibid, 10.

[10] Ibid, 18.

[11] Ibid, 18.

[12] Ibid, 19.

[13] Ibid, 20.

[14] Ibid, 20.