HOUSTON — After five decades of reconnaissance by flyby missions, orbiters, landers and rovers, Mars may be prime for scrutiny from the air, according to scientists and engineers gathered for a NASA-sponsored Mars Program Planning Group (MPPG) workshop organized by the space agency to forge an exploration strategy that achieves more with less.

Proponents presented the three-day gathering with plans for unmanned hypersonic aircraft, slow-moving UAVs, ultra lights and balloons toting cameras, spectrographs, radar and other instruments to prepare the agency and its international partners for the eventual exploration of Mars by humans. “It’s going from the lunatic fringe to conventional wisdom,” says Larry Lemke, an Ames Research Center proponent who has studied aerial platforms on Mars since the early 1990s. “It has to compete it’s way into the program, justify that its costs are better than other ideas.”

His proposal, a solar-powered, eight-bladed vertical-takeoff-and-landing UAV, would operate semi-autonomously, scouting out and flying from one landing site to another as it scanned crater walls in search of fresh water flows.

Multiple platforms

University of Maryland researchers favor a novel, multiple-platform approach comprised of a low-drag orbiter modeled after the X-43 that could dip to altitudes of less than 100 km (60 mi.) above the planet for science surveys. One of 25 RTG (radioisotope thermal electric generators)-powered descent modules would be released from the orbiter’s underbelly. After ejecting 15 smaller “explorers” of its own, the descent module would descend to the ground, functioning as a data recorder and transmitter. The explorers would flutter to the surface like maple seeds, gathering atmospheric data.

“It sounds like a horror movie, but it’s pretty cool,” said Joseph Lukas, one of the Maryland proponents.

The “gas hoppers” proposed by Robert Zubrin, president of the Mars Society, would draw carbon dioxide from the Martian atmosphere as fuel to rocket from sites separated by 10 to 20 km. A winged, solar-powered version would offer 10 times the range. Either version, equipped with ground-penetrating radar, would search for subterranean ice deposits — signaling either a site for microbial life or a resource for astronauts.

Like their aerial rivals, helium- or hydrogen-filled balloons could cover more ground than a rover but remain aloft for weeks to months and fly as a lightweight secondary payload, according to Aron Wolf, a Jet Propulsion Laboratory researcher. The high-altitude, loitering balloon could be ideal for charting regional magnetic fields.

The three-day MPPG workshop, hosted by the NASA-funded Lunar Planetary Institute (LPI), was convened by NASA to assist in the replanning of its long-term Mars exploration strategy in response to deep spending cuts outlined in the space agency’s proposed 2013 budget.

The White House proposed a 40% reduction, or $361 million, for next year. The annual total falls below $190 million in 2015, before rising to $503 million in 2017, according to NASA budget projections.