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Martian Aviators and
Planetary Aerial Vehicle Designers
L.A. Young
December 30, 1999
Over the past year and a half I have had the opportunity
to brainstorm ideas for the possible application of rotary-wing technologies
to NASA space/planetary science missions. Three general categories of
rotary-wing technology application to planetary science missions have
come to mind:
- For planetary science missions to Venus, Mars,
Titan
Vertical lift vehicles (aided by, or solely using,
rotors as the means of propulsion) could potentially be developed
and flown to support both proof-of-concept and extended robotic science
missions to these planets and moon - and, in the case of Mars, possibly
support human exploration of the planet. Almost all of vertical lift
and/or rotary-wing multi-discipline knowledge and technologies would
have some application to vehicle development and mission execution
for planetary science missions to these planets and moon.
- For missions to Jupiter, Saturn, Uranus, Neptune
Vertical lift capability is not required for
any planetary aerial vehicles (PAVs) to be used for scientific investigations
of the gas-giant planets (as they don'9t have any '6surfaces'9 per
se). However, rotary-wing technologies such as rotor aeromechanics
(for propeller design, for example), etc., could still be applicable
for vehicle development for these planets.
- For missions to other planetary bodies in our
solar system (Mercury, Pluto, the Moon, Europa, and other moons, asteroids,
and comets)
The tenuous or nonexistent atmospheres of these
planets, moons, and other planetary bodies prohibit the application
of rotary-wing propulsion. Instead, vehicles employing chemical or
electrical propulsion (rockets or ion-engines) could be used for ballistic
and/or low-level flight and take-off and landing to explore these
planetary bodies. However, even under these circumstances, the rotorcraft
and vertical lift technical communities could still contribute. In
particular, guidance, navigation, and control technologies developed
for hover and nap of the earth low-speed flight could be successfully
applied to rocket/ion-engine propulsion vehicles for low-level flight/exploration.
The actual development of a vertical lift planetary aerial
vehicle is the most intriguing of the possibilities noted above. Most of
my brainstorming and conceptual design work has focussed on studying the
feasibility of a Martian autonomous rotorcraft for science missions (the
'6MARS'9 project). This work is still very preliminary but promising.
The Martian atmosphere is 95% CO2 with the remaining
5% comprised of N2 and other trace gases (see Table 1). Further, the atmosphere
of Mars is extremely cold and thin (approximately 1/100'th of Earth'9s
sea-level atmospheric density). This is roughly equivalent to flying an
aerial vehicle at an altitude of 100,000 feet in the Earth'9s atmosphere.
Given the thin, carbon-dioxide-based Martian atmosphere, developing a
rotorcraft design that can fly in that planetary environment will be very
challenging. It will require, in particular, the development of large,
ultra-light-weight structures and aerodynamic surfaces.
Why vertical lift vehicles for planetary exploration?
For the same reason that these vehicles are such flexible aerial platforms
for terrestrial exploration and transportation: the ability to hover and
fly at low-speeds and to take-off and land at unprepared remote sites.
Further, autonomous vertical lift planetary aerial vehicles (PAVs) would
have the following specific advantages/capabilities for planetary exploration:
- Hover and low-speed flight capability would enable
detailed and panoramic survey of remote sites;
- Vertical lift configurations would enable remote-site
sample return to lander platforms, and/or precision placement of scientific
probes;
- Soft landing capability for vehicle reuse (i.e.
lander refueling and multiple sorties) and remote-site monitoring;
- Hover/soft landing are good fail-safe '6hold'9
modes for autonomous operation of PAVs;
- Vertical lift PAVs would provide greater range
and speed than a surface rover while performing detailed surveys;
- Vertical lift PAVs would provide greater resolution
of surface details, or observation of atmospheric phenomena, than an
orbiter;
- Vertical lift vehicles would provide greater access
to hazardous terrain than a lander or rover.
What are my current plans for the MARS project? I am
working with some robotics and autonomous system folk to develop a conceptual
design of a mission/flight control computer architecture. I am also going
to present soon a technical paper summarizing my assessment of the technical
opportunities and challenges of developing vertical lift planetary aerial
vehicles. Meanwhile, I am continuing to refine an inhouse '6baseline'9 conceptual
vehicle design of a Martian autonomous rotorcraft. I have also helped initiate
(along with Sikorsky Aircraft) an American Helicopter Society Student Design
Competition for college/university students on the design topic of a Martian
autonomous rotorcraft. Finally, I am also looking at developing low-cost
proof-of-concept test articles for demonstrating the critical enabling technologies
underlying MARS.
Hopefully, in part through this work, a future generation
of Martian aviators and planetary aerial vehicle designers will be inspired.
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