Field Journal

The Future of Mars Exploration

By Geoff Briggs
May 30, 2003

Rotorcraft on Mars
By the end of this decade Mars landers are expected to arrive at their destination accurately landing within a few kilometers of their target. Mobility will play a key role if the lander is to adequately explore any chosen site.

Presently, surface mobility is painfully slow and it will remain so for the foreseeable future even as rovers grow larger and acquire nuclear power. Aerial mobility offers many advantages for astrobiology field work. For example, future Mars rovers are expected to travel at speeds of 1 kilometer per week. A rotorcraft could travel at 2 kilometers per minute and it could reach otherwise inaccessible sites. The rotorcraft would need to have the ability to land at, and take-off at unprepared sites on the martian surface, return to its mother lander for refuelling before its next sortie.
The thin martian atmosphere makes rotorcraft flight a big challenge. In simulated martian atmospheric conditions at NASA Ames Research Center, on-going test-stand experiments have demonstrated that such flight can be achieved. By using ultra-lightweight construction techniques and large area rotors appropriate for flight in the thin air we can build a rotorcraft with the ability to explore much more of Mars than will be possible rolling over the rocky surface.

NASA Ames Research Center is currently putting a lot of effort into the autonomous control of rotorcraft for all sorts of terrestrial applications and we expect to inherit this technology to support our martian missions.

We plan to develop a smart (largely autonomous) rotorcraft field assistant (SRFA -- "surfer") that will include field testing at the 20 km wide, 20 million year old Haughton impact crater in the Canadian Arctic. The field test will continue ongoing (and highly productive) astrobiology research at Haughton and will demonstrate a systems level capability to carry out such research on Mars. The rotorcraft will include imaging instrumentation for aerial reconnaissance of multiple sites including ones that are otherwise inaccessible. It will also be equipped with a panoramic camera for post-landing surface characterization and a mechanism on the landing legs to automatically acquire a soil sample.

Autonomous Mars Drill
Since summer 2001 the Johnson Space Center and the Baker Hughes Company have been developing an autonomous Mars drill using an electrically-powered down-hole "tractor" unit. The unit is lowered on the end of a cable, locks itself to the sides of the hole and pushes down from there. The drill is intended to bore holes from meters to kilometers in depth (limited by cable length and available time) and the system will be capable of providing hole stabilization as required. The drill bit design is based on hard rock diamond drilling experience. The drill achieves high energy efficiency by carving away only enough rock to achieve a thin "kerf", creating a core which is then broken off and extracted to the surface by cable. Because of weight considerations and to keep from contaminating the core samples, drilling fluids will not be used. On earth such fluids (sometimes compressed air) are used to cool the bit and to extract the cuttings. For this reason, we will have to drill very slowly and we will have to haul up the cuttings along witth the cores.

Initially we plan to test the drill in a Mars analog environment -- permafrost regions in the Arctic. When we have a reliable system that can return uncontaminated samples we will be ready to plan a mission to Mars to look for "biomarkers" that may be preserved in the ground ice that we believe is common on Mars. Such subsurface access is a new capability and would constitute a combined research effort of NASA Ames Research Center, NASA Johnson Space Center, Baker Hughes Inc., and the University of California, Berkeley.

Field testing with the JSC-BH drill will be carried out near a Canadian base in Eureka on Ellesmere Island in the summers of 2004 and 2005. Core samples will be acquired for study of microbial survival in ancient permafrost that may be millions of years old.