Global Aerospace Corporation developed a revolutionary concept for an overall interplanetary rapid transit system architecture for human transportation between Earth and Mars which supports a sustained Mars base of 20 people circa 2035.
This innovative design architecture relies upon the use of small, highly autonomous, solar-electric-propelled space ships, we dub Astrotels for astronaut hotels and hyperbolic rendezvous between them and the planetary transport hubs using even smaller, fast-transfer, aeroassist vehicles we shall call Taxis.
Astrotels operating in cyclic orbits between Earth, Mars and the Moon and Taxis operating on rendezvous trajectories between Astrotels and transport hubs or Spaceports will enable low-cost, low-energy, frequent and short duration trips between these bodies.
The results of this study effort provides a vision of a far off future which establishes a context for near-term technology advance, systems studies, robotic Mars missions and human spaceflight.
In this fashion, Global Aerospace Corporation assists
NASA in
preparing to conduct human missions of exploration to
planetary and other bodies in the solar system,
expanding scientific knowledge, providing safe and
affordable access to space, and establishing a human
presence in space. Key elements of this innovative,
new concept are the use of:
Five month human flights between Earth and Mars
on cyclic orbits,
Small, highly autonomous human transport vehicles
or Astrotels:
- In cyclic orbits between Earth and Mars
- Solar Electric Propulsion for orbit corrections
- Untended for more than 20 out of 26 months
- No artificial gravity
Fast-transfer, aeroassist vehicles, or Taxis, between
Spaceports and the cycling Astrotels,
Low energy, long flight-time orbits and unmanned
vehicles for the transport of cargo,
In situ resources for propulsion and life support,
and
In 1985 the National Commission on Space (NCOS) published
their plans for the future of space exploration, which
included support to a sustained Mars base. The NCOS plan
assumed the existence of a sustained Mars base of 20 humans
circa 2035, which required significant support in the
form of crew replacement and cargo. The NCOS Mars base
was supported by the use of large (>460 metric tonnes
[mt]) interplanetary space ships for transporting humans
and their material back and forth between the planets
originally conceived by William Hollister at MIT in 1967.
In addition, an entire support infrastructure was envisioned
that includes human, cargo and propellant transfer vehicles,
transport hubs and propellant manufacturing plants.
The new innovative Mars transportation system architecture concept being developed by Global Aerospace Corporation uses small, highly autonomous, solar-electric-propelled space ships, we dub Astrotels for astronaut hotels, for transporting humans to and from Earth and Mars on cyclic orbits between these planets, that were originally conceived by former Apollo astronaut, Buzz Aldrin. Human transfer between planetary Spaceports and Astrotels is by means of hyperbolic rendezvous trajectories using new, even smaller, fast-transfer, aeroassist vehicles called Taxis. Figure 1 illustrates one concept for an Astrotel along with a Taxi docked at one end.
Figure 1. Astrotel and Taxi Concepts
These basic systems combined with other elements
of the Mars transportation infrastructure and a new
analysis of the celestial mechanics and aeroassist
options will enable low life cycle costs, low-energy,
frequent and short duration trips between these bodies.
Figure 2 shows a schematic of the overall concept
for regular human visits to Mars via an Astrotel concept
that uses cyclic interplanetary orbits.
The innovative design architecture developed by Global Aerospace Corporation departs from the concepts in the mid-1980s in several fundamental ways, and these are described below.
Figure 2. Mars Transportation Architecture
Schematic
(Click figure for larger image.)
Our visions for a Mars base circa 2035, its transportation
support concept, and its elements are discussed later.
What Makes This Concept
Revolutionary?
First, this new transportation systems
architecture assumes the use of highly autonomous on-board
systems to a) reduce the number of crew and b) their occupation
time of the transfer space ships to only five months in
interplanetary space. Experience with untended
space flight on the Russian Mir and the construction phase
of the International Space Station make it clear that
crew are not essential to maintain support systems. Reducing
the size of crew and reducing the duration of their time
spent in space reduces the size of the space vehicle and
its complexity and the amount of logistics supporting
the daily needs of the crew. In addition, by eliminating
crew on long flight legs, we eliminate the need for additional
Taxis for return to Spaceports thus reducing the number
required by one half. Because these Taxis are not carried
on these long trajectory legs, Astrotel propulsion requirements
are therefore reduced.
Second, in previous plans, a means to generate artificial
gravity was required due to the lengthy crew stay time
(up to 2 1/7 years). The Mir experience, Russian (one
year) and US (Shannon Lucid's 6 month flight), indicates
6 months of zero-g are clearly tolerable. When transit
times are reduced to no more than 5 months, artificial
gravity is no longer necessary thus reducing mass, complexity
and risk.
Third, in past planning, conventional propulsion has
been envisioned for the crew transport space ships using
a Taxi's rockets. We are proposing instead to use solar
electric propulsion for the periodic course corrections
that are required for Astrotels (major corrections will
generally occur during untended periods). Utilization
of low-thrust Solar-powered Ion Propulsion reduces propellant
mass requirements by a factor of 9. The cost in propellant
mass for conventional chemical propulsion for course
corrections for the large 460-mt vehicle over 15 years
is more than 173 mt (more than twice our entire proposed
Astrotel vehicle!). If we combine the interplanetary
vehicle size reductions with SEP, the total reduction
in propellant required for the Astrotel in 15 years
is less by a factor of sixty! This reduction has a tremendous
mass and cost multiplying effect since all this propellant
must also be mined, manufactured and stored, transported
to the Spaceport and injected onto high-energy trajectories
required for rendezvous with the Astrotels. See Table
1 for a comparison of several NCOS and preliminary NIAC
study results including propellant requirements. As
they are developed, evolutionary improvements in propulsion
technologies will further reduce propellant requirements,
but they probably will not change the fundamental architecture
explored in this study.
Table
1. Comparison of NCOS and NIAC Study Results
Item
NCOS
Study
NIAC
Study
NIAC Improvement Factor
Cyclic Transport Vehicle Size, mt
460
70
7
Total 15-year Propellant and Consumables, mt
34,335
2,011
17
Lunar LOX Production Rate, kg/day
4,014
73
55
Phobos LOX Production Rate, kg/day
1,066
189
6
Primary Power Generation Mode
Nuclear
Solar
--
Finally, in previous planning, all cargo except certain
propellants needed at Mars, went via the same large
crewed interplanetary space ship. The implication was
that a lot of propulsive energy was being expended on
hardware and supplies that could take a lot longer to
get to Mars without detrimentally effecting the operation
of the base.
All of these departures from the plans originally envisioned
by the NCOS result in significant reductions in mass
requirements and therefore they have enormous implications
to overall energy requirements of a Earth-to-Mars transportation
system. Reduced energy requirements impact the design
of other elements of the transportation infrastructure
and the cost of their development and operations. Since
this new concept for support of a future Mars base results
in a significant reduction in operations cost over previous
concepts, a Mars base could be much the closer to reality.
In fact, elements of this concept could be implemented
at the very beginning of Mars exploration insuring that
the first humans to Mars begin the permanent inhabitation
of this our nearest, most hospitable neighbor.
The key elements of the overall Earth-to-Mars interplanetary
rapid transit infrastructure in support of a permanent
Mars base are listed below:
Cycler orbits between Earth and Mars that enable
fast, frequent transfers between these planets
Small, human transport space ships, or Astrotels,
on cycling orbits between planets,
Orbital Spaceports at the planets
Very small, fast, hyperbolic transfer vehicles,
or Taxis, between Spaceports and Astrotels.
Propellant and life support in situ resource manufacturing
plants
Cargo vehicles that utilize low-energy, long-flighttime
orbits to transport propellant and low value cargo
to and from planets
Shuttles to and from Spaceports and planetary surfaces
Potential Significance To NASA
The proposed concept provide a means to expand human exploration to Mars and by providing a transportation architecture that could be put in use to explore other planetary bodies, potentially near-Earth and Main Belt asteroids. It could also enable frequent, short visits to Mars by scientists. Opportunities for extended direct and teleoperated field science (e.g. geology) by scientists at Mars will swiftly expand scientific knowledge of the planet and increase our understanding of its similarities and differences with our own planet. This transportation architecture offers transport to and from Mars at an expected very low life cycle cost. High life cycle costs will limit Mars exploration by Apollo-like expeditions. If life cycle costs can be significantly reduced, permanent exploration and inhabitation of Mars can be argued as being cost effective. This concept contributes to the establishment of a permanent human presence on the planet Mars. Finally, this concept could also provide future direction to NASA regarding flight system technology development that could set the stage for Mars expeditions in the future.
