Based on the lovely green rock, olivine, also known as the gemstone, peridot, a Virginia Tech graduate student has created a mineral lifetime diagram that provides the a clue to when and for how long there might have been water on Mars.

Amanda Albright Olsen of Altoona, Pa., a doctoral student in geosciences at Virginia Tech, will present the research at the Geological Society of America national meeting in Philadelphia Oct. 22-25. Virginia Tech Geosciences Professor Donald Rimstidt of Christiansburg, Va., is co-author.

Olivine, a silicate mineral rich in magnesium and iron, is found on earth in volcanic rock (basalts). It has also been spotted on Mars – most recently and in significant amounts by NASA’s Mars Odyssey spacecraft (Geology, June 2005). Because life requires liquid water and because olivine dissolves in water, Olsen set out to establish how long it takes olivine to dissolve. The answer could help scientists determine if there was liquid water on Mars long enough for life to develop.

“Our goal is to produce a robust analysis of olivine dissolution that can be used to predict olivine grain lifetimes,” Olsen said.

She used published information and laboratory studies to construct a baseline model, and introduced controlling factors, such as pH and temperature. Since environmental factors have often resulted in slower dissolution rates in the field than in the lab, she compared her results with an analysis of olivine in natural environments by Virginia Tech Geoscience Professor Michal Kowalewski and Rimstidt (2003), who determined average mineral grain lifetimes based on radiometric dates.

Olsen and Rimstidt’s conclusion is that the Martian olivine could take between slightly less than a million years to as long as many millions of years to dissolve in water. She cautions that pH is a highly controlling factor and a more precise estimate awaits information on the chemical conditions on the Mars surface.

“Amanda’s research will be a tool to help others pin down it down,” Rimstidt said.

“Regardless of what physiochemical conditions that we postulate for early Martian history, we can now propose a scenario and ask, “Is it reasonable to expect that life could have originated in this time frame?” Olsen said.

October 19th, 2006 | Physics | No comments

The ESA is gearing up for the end of the mission of its first spacecraft towards the Moon. SMART-1 was launched on September 27, 2003, and it reached the Moon in November 2004 after a long spiralling around Earth. So far, the mission has been a success and will end in a dramatic fashion.

Initially planned to last 6 months, the SMART-1 mission got a one year extension and further studies were completed. Now the delay is over and the spaceship will be a tool for one last experiment. Since the spacecraft is trapped by the Moon’s gravity, it will come down crashing on the Moon on September 3rd. The last bits of propellant were used to boost the orbit of SMART-1, giving it that one year extension. Out of xenon propellant, SMART-1 used its hydrazine thrusters to perform the last major manoeuvre at the end of June 2006 to further stretch the mission lifetime and win three more weeks of operations.

SMART-1 first contribution was to show that its ion engine could be used efficiently for interplanetary travel (assisted by gravity slingshots). To cover the 385,000 km distance that separates the Earth from the Moon if one travelled in a straight line, this remarkably efficient engine brought the spacecraft on a 100 million km long spiralling journey on only 60 litres of fuel!

SMART-1 also tested future deep-space communication techniques for spacecraft, techniques to achieve autonomous spacecraft navigation, and miniaturised scientific instruments, used for the first time around the Moon. Also, a small instrument on the satellite as shown the first detection from orbit of calcium on the Moon. This could help scientists determine if the Moon form from part of the Earth.

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August 18th, 2006 | Physics, Space | No comments