Herbert V. Frey, Ph.D., head of the Geodynamics Branch of NASA's Goddard Space Flight Center, spoke at Hamilton on Thursday, Dec. 2, giving a lecture titled "Mars: Less Than The Earth, More Than The Moon." Dr. Frey outlined what science knows about the geology of Mars in comparison to that of the Earth and the Moon. He also dicussed what we are learning from the current NASA exploration of Mars, including evidence about the possibilities of water and primitive life on the planet.
Frey began by comparing Mars to the Earth and the Moon, saying that the study of "comparative planetology" can help us learn about an unknown planet by putting it in terms of things we are already familiar with. Mars is a truly intermediate enviroment between the two bodies, being about half the size of the Earth and twice the size of the Moon. Size is a very important factor in determining a planet's environment, not only because of gravity but because of atmosphere and internal heat.
The Moon is a very simple planet geologically, Frey said. The bright, heavily cratered parts of the Moon are older, and were impacted by many large objects as the crust cooled. The dark "seas" on the Moon's surface are the relatively newer portions of the crust. However, the Moon has been inactive for a very long time now, and has in fact been a "dead" body for most of its history. In contrast, the Earth is a very geologically active planet with a "slow boil" inside its core. Frey briefly reviewed how the "restless Earth's" crust is altered by plate tectonics, and how phenomena like earthquakes and volcanoes exist at the borders between the plates. Another important characteristic of the Earth that sets it apart from the rest of our solar system is that it is the right size and the right distance from the Sun to sustain large bodies of liquid water, which is essential for life.
Mars is a mix of the Earth and Moon, Frey said, and we are finding out more about this through our current exploration of the planet. Mars is a geologically active planet with large volcanoes and a layered crust, but no plate tectonics. Using the Mars Global Surveyor, Mars Oddysey and Mars Exploration Rover programs, we have learned a lot more about the planet's crust. Frey showed pictures from the rovers that displayed the two different types of rock on the surface - that which is above the crust and that which is embedded into it.
Recent evidence shows that Mars had liquid water in its past, and even more than we thought, said Frey. New images from the Mars orbiters show evidence of a previously unrecognized valley and tributary system, suggesting precipitation in the planet's distant past. There are also gullies which suggest that water has seeped from lower ice-rich layers of the crust in more recent times. There are also various kinds of chemical evidence that can be interpreted to show the existence of water. Frey said that while this evidence is persuasive, one has to worry about scientists interpreting the data to fulfill their own hopes to find water.
After establishing that Mars had liquid water in its past, the next question is obviously whether Mars had supported life. Frey said that there is currently no unambiguous evidence for life on Mars. However, there are some interesting findings that suggest it as a possibility. Meteorites found in Antarctica that are thought to have come from Mars show evidence of the life processes of very primitive microbial life. There are also regions on Mars that may have been capable of sustaining life in the past when they had both liquid water and volcanic heat.
Frey then discussed what's next for the Mars Exploration program. NASA already has new things planned for the near future, including a new orbiter with higher photo resolution and a rover called the Mars Science Laboratory that will be able to further test the surface environment. Some other ideas for the future include balloons and airplanes for low atmosphere work, cliff hanging robots and coring below the planet's surface. Manned exploration is also a prospect for farther off in the future. Frey said that he believe this is not a matter of if, but when. Currently, he believes, we can not afford such an endeavor with our deficit economy. He also said that the United States should not attempt such an endeavor on its own, but cooperate with the world's other space agencies. In the meantime, a longer robotic program is needed to figure out how we could land and sustain astronauts on the planet.
Dr. Frey's talk was sponsored by the Emerson Literary Society as the inaugural lecture in its "Tell Me What You Know" series.
-- by Caroline O'Shea '07
