One now knows that it is not necessary to take all equipment
from Earth to be able to go to Mars, stay there and to come back.
This is the idea of Mars Direct.
Mars Direct Plan begins with the launch of an unmanned Earth Return Vehicle,
or ERV, that will, on landing on Mars, manufacture its own propellant,
thereby laying the groundwork for the arrival of astronauts.
Two years later a manned spacecraft and another unmanned
ERV blast of for the Red Planet; the astronauts head for the previous landing
site, while the unmanned craft prepares for the next manned mission, scheduled
to arrive in another two years.
The project can continue for as long as desired, leaving
behind a string of base camps across the Martian surface.
The astronauts get on Mars after half a year of travel,
stay there for two years and get back to Earth in another half year of
The goal is not beyond out reach. No giant spacecraft
built with exotic equipment is required. Indeed, all the technologies needed
for sending humans to Mars are available today.
We can reach the Red Planet with relatively small spacecraft
launched directly to Mars by booster rockets embodying the same technology
that carried astronauts to the moon more than 30 years ago.
(1) 3H2 + CO2 -->
CH4(to storage) + H2O
(2) 2H2O -->
2H2 (back to (1)) + O2(to storage)
(3) CH4 + 2O2 -->
CO2 + 2H2O
(4) CO2 --> C + O2
The 6 tons of hydrogen brought from Earth react with the
Martian atmosphere ( 95% CO2 ) to produce water ( H2O
) and methane ( CH4 ). This process (1) is called methanation.
Methane has the advantage that it is easier to store than hydrogen. The
methane is liquefied and stored and the watermolecule is electrolyzed to
get hydrogen and oxygen. The resulting oxygen gets stored and the hydrogen
is used in process (1) again.
As a result, we get 48 tons of oxygen and 24 tons of
methane ( compare that to the amount of hydrogen brought from earth! ).
But to ensure that the methane burns efficiently, further
36 tons of oxygen have to be produced (3).
This is done by braking apart the CO2 of the
Martian atmosphere with the energy of the 100 kW reactor.
After 10 months, we have 108 tons of propellant. This
is 18 times more than the original feedstock needed to produce it.
Much less mass has to be brought from Earth. This is the
main reason why the Mars Direct mission is much less expensive than the
The return trip requires 96 tons of propellant, leaving
12 tons for the operation of the rovers.
Additional stockpiles of oxygen can also be produced;
both for breathing and for conversion into water, by reacting the O2
with the H2 brought from Earth.
The ability of doing this also greatly reduces the amount
of life-supporting supplies that must be hauled from Earth.
By reducing the amount of life-supporting supplies, the
price of the mission gets greatly reduced.
It has been estimated that the entire mission would cost
This is not much more expensive than the $20 billion
This might still seem to be a lot of money, but spent
over 10 years, this amount would constitute an annual expenditure of about
20 percent of NASA's budget, or around 1 percent of the U.S. military's
It is a small price to pay for a new world. (Robert
Zubrin, astronautical engineer, president of the Mars Society and author
of The Case for Mars)
This is what the base on Mars would look like:
The rocket in the back is the ERV (Earth Return Vehicle), the tunafishcan-like
looking thing is the habitat. In the front, you can see a greenhouse where
food is produced. A greenhouse would be impossible on the Moon. In the
far-back solar panels are visible which produce 5 kW of electricity. Close
to the habitat is an antenna, used to keep up contact with Earth. Two rovers
are also visible. One of the three astronauts is hooking up some instrumentation
on a balloon that will float above the surface. On the top of the picture
the two Martian Moons are visible. The bigger one is Phobos, the smaller
The habitats have the advantage of being able to be used
on any celestial object mankind would like to land on. Here you can see
a colony on the Moon, where the inhabitants have Mars-habitats.
Here is a short table of "facts" that previously made
a manned Marsmission impossible and how it is now made possible with Mars
|Launch cost to high
||Launch cost cheaper through ability of producing propellant,
oxygen and water on Mars, thereby reducing mass at launch.
Further reduction through new technological developments.
|Development takes to long ( 30 years )
||The devolopment would now take 10 years with only 20%
of NASA's annual budget a year. The reason for the longer development time
of the "Mega-spacecraft" mission is due to its size. It would have to be
build in orbit and would be enormous. So the construction would have taken
longer and it would have taken longer to find the funds.
|0 gravity conditions during the flights back and forth
are very harmful.
||With Mars Direct, there are no 0-g conditions. The manned
craft is attached with a tether to the life-support systems that is sent
at the same time. Both are sent into rotation around one another, so that
the astronauts profit of the centrifugal force as artificial gravity. Gravitational
conditions will be similar to those on Mars.
|Radiation to high.
||During the stay on Mars radiations are not too dangerous
thanks to Mars' thin but never the less existing atmosphere. During the
flight, cosmic and solar radiations come into account. Solar flare radiation
gets completely shielded with 12 cm of water. The residual cosmic-ray dose,
about 50 rem for the 2,5 year mission, represents a statistical cancer
risk of ~1%, roughly the same as the risk from smoking for the same amount
|Contamination from Mars-bacteriae.
||-Mars almost certainly is now dead, at least on the surface,
where astronauts intend to land.
-If there is a Mars-bacteria, it won't be harmful to
humans, because it would be adapted to Martian conditions.
-If there is a Mars-bacteria, we're already infected:
We keep getting bombarded with rock from Mars. This bacteria would easily
have survived and infected humanity.
-There are guys at NASA who make sure the astronauts
are not infected before they get free again.
||It isn't a good idea to land during a sandstorm, so the
rocket would have to stay in orbit until the storm stops. However, during
the astronaut's stay on Mars, a 200 km/h storm wouldn't be dangerous; it
would exert the same force as a 20 km/h breeze on Earth.
||Compared with the stresses dealt with by previous generations
of explorers, the adversities that will be faced by the hand-picked crew
of a Mars mission seem extremely modest.
-- Consumable Requirements for Mars Direct Mission
with Crew of Four
||Daily Need per person (kilograms)
||Daily waste per person (kilograms)
||Payload for 200-day return flight (kilograms)
||Payload for 600-day stay on surface (kilograms)
-- Mass Allocation for Earth Return Vehicle
|ERV cabin structure
|Solar array (5 kilowatts of electricity)
|Reaction control system
|Communications and information management
|Furniture and interior
|Space suits (4)
|Spares and margin (16 percent)
|ERV propulsion stages
|Propellant production plant
|Nuclear reactor (100 kilowatts of electricity)
|ERV total mass
Other manned missions:
There are still other plans for manned missions to Mars
like an Exhaust-Modulated Plasma Rocket that could bring people to Mars
within 90 days.
This mission has the disadvantage of being far more expensive
( construction has to be made in orbit, new technology ) and the astronauts
could only stay for a far shorter lapse of time than with the Mars Direct
mission, probably insufficient for answering a few major questions about
Mars, e.g: The existents of life or the abundance of water.
Anyway, here is how it works:
The Exhaust-Modulated Plasma Rocket is well-suited
for "split-sprint" missions allowing fast, one-way low-payload human transits
of 90 to 104 days, as well as slower, 180-day, high-payload robotic precursor
The idea of it is to ionize hydrogen and to push outwards
with the help of a magnetic field. Note that hydrogen is much more difficult
to store than methane, for example.
Most propellant is used to escape Earth and at arrival
close to Mars. The rocket is launched when Mars is closest to Earth, which
allows a 90 day transit time, but only a 30 day stay on Mars.
Although I know of no estimated price, the mission would
probably be by far more expensive than the Mars Direct mission.
Other missions would also be possible. Atom or hydrogen
bomb-rockets would allow humans to get to Mars really quickly, but would
also be extremely dangerous and even forbidden because of the space-nuclear
Fusion engines would be another high-speed transportation
method, but we don't have the technology yet.
Anti-matter rockets would probably work and be extremely
powerful, but nobody knows how to produce and to store large quantities
of Anti-matter and way of figuring that out is in site.
But fortunately, we don't need such exotic technologies
to reach Mars, since Mars Direct would work fine and be far less expensive.
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