With an international flotilla of Mars-bound probes nearing their target, plans for future missions to the red planet, possibly paving the way for human exploration, are taking shape.

Following the twin Mars rovers set to land in January 2004, NASA has a progressive, step-by-step agenda of Mars orbiters and landers slated for launch throughout the decade.

The Mars Reconnaissance Orbiter (MRO) is being readied for liftoff in August 2005. It will scrutinize the red planet like no previous orbiter and is equipped to relay images and science data to Earth via the widest dish antenna and highest power level ever operated at Mars.

Current Mars missions are returning data “over the equivalent of a dial-up modem line,” said James Graf, project manager for the MRO at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “When we get to Mars, and at the planet’s closest approach to Earth, we’re going to be able to have the equivalent of two digital subscriber lines. It’s going to be an amazing amount of data coming back.”

The MRO’s duties are divided into three areas: global mapping, regional surveying and close-up scrutiny of specific spots on the planet’s surface. Central to the mission is the High Resolution Imaging Science Experiment. Built by Ball Aerospace and Technologies Corp. here, this zoom camera will operate in the visible part of the spectrum to spot objects as small as a dinner table. This should yield data with unprecedented detail of features including small objects in the debris blankets of mysterious gullies, the geologic structure of canyons, craters and layered deposits.

The spacecraft will pinpoint sites of high science payoff for future landers, plus help ascertain touchdown hazards for robotic vehicles and, possibly, for future human expeditionary crews. The MRO underwent a critical design review in May 2003, said Kevin McNeill, MRO program manager at prime contractor Lockheed Martin Space Systems of Denver. Mission elements, including solar panel segments, the composite skeleton of the spacecraft and engineering development units that are precursors to command and data handling equipment, are taking shape, he said.

Integration of the spacecraft components is scheduled to start in April. “That’s when we start to build up the entire system to make sure it all plays together,” McNeill said.

Beyond the MRO

The MRO is to be followed by the Mars Phoenix lander, the flagship spacecraft for NASA’s Scout line of innovative and relatively low-cost explorers. It is slated to launch in August 2007 and land at an as yet unspecified spot in the northern latitudes of Mars, where it will characterize the local soil content and atmosphere.

The Phoenix lander is based in part on hardware lost when NASA’s Mars Polar Lander apparently crashed near the planet’s south pole on Dec. 3, 1999. A follow-on lander was being tested to fly as part of the 2001 Mars Surveyor program, but this work was halted after the failure. The hardware was stored at Lockheed Martin in 2000, and is now being utilized for the Phoenix mission.

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“We’ve ramped up and things are under way,” said Peter Smith of the University of Arizona’s Lunar and Planetary Laboratory in Tucson and Principle Investigator of the Phoenix mission.

The Phoenix lander will feature a powerful robotic arm that will plow into the martian soil to a depth of roughly 1 meter. This trench digging could reveal a habitable zone that may exist in the ice-soil boundary.

Soil samples scooped up by the robotic arm will be analyzed by the lander’s Thermal and Evolved-Gas Analyzer, which will look for contents including water, carbon dioxide, water-ice, minerals and organic materials that may have formed when Mars had a warmer, wetter climate.

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The planned buildup of Mars orbiters and landers is the impetus behind the Mars Telecommunications Orbiter, which would be lofted toward the planet in 2009. This spacecraft would utilize laser-optical communications technology as well as radio frequency to relay unprecedented quantities of Mars data to Earth.

Also planned for launch no later than Dec. 31, 2009, is NASA’s Mars Science Laboratory, a long-duration rover that would serve as a mobile scientific laboratory. “This is our first nuclear Mars mission in a long time,” said Ed Weiler, NASA associate administrator for space science. Nuclear generators were used in NASA’s Viking Mars landers in the 1970s, he noted.

At a Dec. 2 briefing on the planned January landing of NASA’s relatively short-duration Spirit and Opportunity Mars rovers, Weiler said the nuclear-powered Mars Science Laboratory is expected to last for well over a year, perhaps as many as five years. It will be able to travel hundreds of kilometers over the course of its mission, he said.

James Garvin, lead scientist for Mars exploration in NASA’s Office of Space Science, said the MRO will be tasked to target the mobile lab “to the most compelling site it can safely reach. The rover will be armed with instruments designed to read the signatures of the building blocks of life.

Pathways to Future Exploration

For the second decade of the 21st century, NASA has developed a science-driven set of options, tagged as pathways, Garvin told Space News. The plan involves a Scout mission competition in 2011, based on the status of Mars discoveries at that time.

Beyond 2011, Garvin added, the pathways branch out according to different exploration strategies, which will be pursued via Scout missions.

Already under study is a Ground-Breaking Mars Sample Return mission, a low-cost approach to retrieving martian soil samples for analysis on Earth that could launch in 2013. An alternative pathway calls for an Astrobiology Field Laboratory, which would visit a site on Mars where evidence of past hydrothermal activity has been observed. Instruments toted by this mobile lab could perform on-the-spot life detection studies, Garvin said.

“I am guardedly optimistic we will continue to press on, and learn about the real Mars…which is always better than any Mars we can imagine,” Garvin said.

Setting Foot on Mars

The Mars science data to be collected over the next decade-and-a-half will help bring a possible human expedition to the red planet more clearly into focus. One launch date that is appealing to some advocates of such a mission is 2019 — the 50th anniversary of the Apollo 11 moon landing.

The current exploration campaign “will continue to add substantially, if not dramatically, to our scientific understanding of Mars, and will help obtain some of the data needed to eventually, safely send humans to Mars,” said Lewis Peach, chief engineer for the Universities Space Research Association of Columbia, Md.

But before a human expedition to Mars can be undertaken, Peach said, scientists need to learn more about the planet’s radiation environment and chemical makeup.

Although NASA’s Mars planning beyond 2009 is somewhat hazy, Peach said it should be possible to pursue missions that serve both planetary science as well as human exploration goals. One convergent area of study is Mars’ past, present or future ability to sustain life, he said.
Technology demonstrations also will be needed to pave the way for human exploration of Mars, Peach said. ”The fact that these investigations are not a part of the planning horizon for the next 10 years is troubling to many that would advocate a near-term human mission to Mars,” he said.

Risk management is key, Peach said. “If the environment and useable resources are well known, and the technology and processes well developed, the risk is substantially reduced. If there is a lot of uncertainty, as many believe is the case now, then something needs to be done to reduce this risk,” he said.

Peach acknowledged that scientists cannot learn everything about Mars before humans set foot there. “Mars will offer seemingly inexhaustible mysteries to tackle for the foreseeable future, probably even more so when humans can scientifically explore Mars in person,” Peach concluded.