Earth and Mars may sit side by side in the solar system, but at first glance they have little in common. The Red Planet is colder — its average recorded
temperature is -81 degrees Fahrenheit — more desert-like, and surrounded by a thinner atmosphere. Yet there are also remarkable similarities: both planets go through seasonal cycles, and they have comparable surface characteristics, such as dried-up riverbeds and volcanoes.
Many astronomers believe the two planets started out with similar climates and then diverged over time. But key questions remain: what happened to the water that was there? And how did the atmosphere change?
These questions are the basis for two proposals recently selected by NASA for a nine-month feasibility study designed to examine how Mars
evolved and to explore the potential habitability of the planet. In about a year, NASA will select the winning study for the second mission of its Mars Scout program, which is scheduled to launch in 2011. Each proposal focuses on the “escape” of the upper atmosphere and the subject of water on Mars. One includes the research of Michael Mendillo, a College of Arts and Sciences professor of astronomy and of electrical and computer engineering at the College of Engineering, and John Clarke, a CAS professor of astronomy, is a contributor to the other — making Boston University the only school in New England to have a professor on each research team.
"Both finalists are in the same area of science,” says Mendillo (GRS’68,’71), “which shows that NASA feels this is a high priority of study.”
Mendillo, working with Alan Stern, a leading planetary scientist from the Southwest Research Institute, in Boulder, Colo., is a member of the Great Escape (TGE) team. The TGE plan is to fly a satellite “that will orbit Mars with a group of instruments to study various aspects of the current Martian atmosphere,” Mendillo says. “The goal is to look for indicators that will help us understand the status of the Martian atmosphere in the distant past.”
Clarke is part of the Mars Atmosphere and Volatile Evolution Mission (MAVEN) team, led by Bruce Jakosky, a University of Colorado geology professor and astrobiology specialist. If selected, the MAVEN team plans to send a spacecraft to orbit Mars for at least two years, equivalent to one Martian year, to collect data on the planet’s atmosphere, which will then be sent back to Earth for analysis. Team members hope to explore the possibility that Mars’ upper atmosphere may have blown off into space because of the planet’s gravitational pull, which is weaker than that of Earth.
Researching how Mars lost its atmosphere will help scientists understand a planet’s potential habitability and how it evolves, including the possibility that if life at one time existed on Mars, it could have been disrupted by atmosphere changes, says Clarke, as well as the impact of global change.
In addition, Mendillo points out, understanding Mars’ atmosphere will provide important details for future manned missions to the planet.
The 2 proposals were selected from a field of 20 for the nine-month $2 million feasibility studies funded by NASA. While the science of both proposals has been accepted, the two groups need to show that they can perform the 2011 Mars Scout mission on time and within its $475 million budget.
“It is the goal of science, and specifically the goal of astronomy, to understand our place in the physical universe,” says Mendillo. “We have eight wonderful objects to study, but Mars is extra appealing because we see that it changes.”