The Mars Rover has already confirmed the presence
of various organic chemicals on the Red Planet, but it is
unable to access hard-to-reach areas, leaving much of the
“Our solution is a marsupial spacecraft - a daughter
ship if you will - that will leave the larger space craft
… land, and take samples after imaging and mapping,”
explains Michael DuPuis, robotics and autonomous
systems engineering and researcher at NASA’s Kennedy
Space Center, as well as the co-principal investigator for
the Extreme Access Flyer (EAF) project.
The EAF project, being developed by engineers at
NASA Swamp Works, is working to develop the small,
low-cost flight systems, called Extreme Access Flyers, to
preform risky exploration and prospecting.
“These missions would be followed up with a more
sophisticated ISRU architecture, wherein the vehicles
would be able to harvest the local resources for years,”
The team is particularly interested in using the Flyers
to find water ice, because its uses are multifold. Water
ice can sustain a human life support system and when
split into hydrogen and oxygen, it can be used as rocket
“We can also recombine hydrogen and oxygen in a fuel
cell to produce electrical power when there is not enough
sunlight to produce power,” adds DuPuis. The volatile
resources can be compressed and used in a cold gas
propulsions system, such as the one that propels the Free
Flyer, or reacted in a chemical combustion rocket engine.
NAVIGATION & CONTROL
The team is working to develop two spacecraft
architectures: one for the near-zero gravity on asteroids, and
one for partial gravity
on the moon and Mars.
While the craft will operate
in different gravity levels, the
overall concept remains the same,
and in both cases, the propulsion systems are based on cold
“Being part of a sustainable ISRU architecture is one reason
why we’re looking at cold gas propulsion,” explains DuPuis.
Another reason is its simplicity, high reliability, and robustness.
“It’s less risky and cheaper to use these simpler fluid-mechanical systems for flight propulsion, versus combustion
or various other propulsion systems,” adds DuPuis.
While the final vehicles will be powered by cold gas
thrusters, the current Mars Free Flyer prototype still uses
rotary ducted fans to serve as a terrestrial proof of concept.
“It’s something that we implemented very quickly,” explains
DuPuis, which allowed the researchers to develop other
aspects of the vehicle, such as the guidance, navigation, and
control system (GNC). According to DuPuis, the vehicle’s
most complex system is the GNC.
The GNC receives input from various sensors and has
to process that information in a system aptly called a state
estimator, as it continuously measures the vehicle’s various
states (position, velocity, rotational rates, etc.). The system is
also called a navigation filter or sensor fusion engine.
The state estimator must also be able to translate between
different reference frames based on different mission
The future of space flight depends on in-situ resource utilization (ISRU) – essentially, living off the
land in space. However, the first step in
using these resources is finding them.
By Melissa Fassbender, Editor
A prototype built to test Extreme Access Flyer systems in different
environments. (All image credit: NASA/Swamp Works)