In a packed room of scientists, program managers, software specialists, and spacecraft builders, it was show and tell time.
The scene is the Mars Landing Site Selection Workshop, held here October 17-18. Those gathered are assigned the duty to reduce the number of possible landing places for the dual rovers. Among the sites: Melas Chasma, Central Valles Marineris, Isidis Basin, the craters Gusev and Gale, and Eos Chasma. Each area is steadfastly backed by a "science spokesperson" making the case that their piece of Martian real estate is where to go.
"The real problem is that weve got a bunch of really exciting sites. Its not that they are all boring and not going to offer scientific potential," said John Grant, co-chair of the Landing Site Steering Committee from the Center for Earth and Planetary Studies at the Smithsonians National Air and Space Museum. "Weve got some really good ones. Theres going to be some hard decisions to make," he told SPACE.com.
Science and safety
This weeks meeting is part of a step-by-step process to whittle down a large number of Mars landing targets. Around April of next year, a final selection of the two sites will be determined. "I think were on a reasonable track to do that," said Matt Golombek, a Mars scientist at the Jet Propulsion Laboratory here, and also a co-chair of the Landing Site Steering Committee.
Finding the sweet spots on Mars large ellipses within which the rovers land and are exciting for scientists is also a game of pinning down landscape that is flat, smooth, and non-threatening to the rovers. "Everyone has to work together to make sure we get the best site for the science that is absolutely safe, as best as you can determine," Golombek said.
The just chosen four sites -- Terra Meridiani, Melas Chasma, Gusev Crater, and Athabasca Vallis (Elysium) will now get extra-special scrutiny by Mars rover engineers as well as scientists. More images of these sites are to be taken by the now orbiting Mars Global Surveyor.
Additional data is likely to be accumulated by the Mars Odyssey, set to arrive at the planet next week, Grant said
Getting down and dirty
The Mars 2003 missions mimic that of the Mars Pathfinder project in 1997.
After aeroshell entry into the thin Martian atmosphere, a parachute deploys to slow the spacecraft. Then small rocket engines fire to slow the vehicles down prior to impact. Airbags inflate and then cushion the delicate rovers as they bounce over Martian landscape. The Mars Exploration Rovers (MER) are individually launched and go through the same nail-biting sequence called entry, descent, and landing.
After touchdown on Mars, the rovers will each have far greater mobility than Sojourner, the cute and cuddly craft that rolled about a small area. These bigger Mars Exploration Rovers (MER) can trek up to 330 feet (100 meters), per Martian day. That is almost as far in one Martian day as the Sojourner rover did over its entire lifetime.
Each MER will drop atop different regions of Mars. They are built to scout about and be on the lookout for evidence that liquid water may have been present in the planets past. Rocks and soils will be analyzed with a set of five instruments on each rover. They are collectively known as the Athena payload.
Starting in January 2004, MER surface operations will last for at least 90 Martian days. Depending on the health of the twin rovers, science collection work could continue longer.
Balancing act
Engineers are busy at work on readying the Mars rovers for launch in 2003.
"From our point of view, were ahead on some things and behind on others. But we think we have the time, the energy, and the resources to pull it off," said Robert Manning, JPL manager for systems engineering of the Mars 2003 rovers. "This has a similar feel as we had on Mars Pathfinder. We learn some new things, change or modify this. Were testing and building equipment as fast as we can. Its an amazing production and a lot of parallel work," he said.
"Were at a point where the pencil sharpening is done and now physics and testing is giving us information of what to do next," Manning told SPACE.com.
While a number of constraints about the rovers dictate where they will ultimately land, the balancing act between science and engineering requirements is a friendly tension.
"Everyone knows the importance of getting down safely and working," said Mark Adler, Mars Exploration Rover Deputy Mission System Manager at JPL. "Were going to pick two sites that are safe enough and that have the best science that we can get," he said.
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