Mars for Less
Encyclopedia
Mars for Less is a proposal for a near-term human Mars expedition that involves the use of existing Evolved Expendable Launch Vehicles (EELVs, or alternatively, Medium-Lift Launch Vehicles, MLLVs). The MFL plan claims that the barrier to entry for a manned Mars mission can be lowered significantly by avoiding development costs in launch vehicles, particularly heavy lift launch vehicle
s (HLLVs) that many think are required for human space exploration. While more complex than many other mission proposals, Mars for Less has strong economic arguments, including avoiding launch vehicle development costs, and offering the prospect of an anchor tenent for the currently over-supplied launch vehicle market, which could result in reduced launch costs and incentives to develop reusable launch technology. The MFL plan was developed by aerospace engineer Grant Bonin in 2003 when he was a student at Carleton University
.
's Mars Direct
mission design, in which two different spacecraft
are used for a single human expedition. One spacecraft (called the Earth Return Vehicle, or ERV) is sent to Mars unmanned on a trajectory similar to a Hohmann Transfer Orbit
before the crew. This vehicle lands and fuels itself using a Sabatier process, creating methane/oxygen rocket fuel (bipropellant) out of carbon dioxide obtained from the Martian atmosphere and a relatively small amount of hydrogen imported from Earth. Once the ERV is fuelled, the crew is launched to Mars on a free return trajectory
. The crew arrives after about 180 days and lands in the proximity of the ERV. They spend about 500 days on the surface exploring, then return to Earth in the ERV.
The Mars for Less plan is different from Mars Direct in that it uses multiple launches of existing launch vehicles, instead of a few launches of heavy lift boosters. In the MFL plan, separate components are launched individually to low-Earth orbit, where they are mated together over the course of about half a year. Each component is itself autonomous, so that only an orbital assembly, and not construction, would ideally be required. By avoiding the development of a heavy lift launch vehicle like NASA's proposed Ares V
, such a mission could theoretically be undertaken today.
While Bonin maintains that better economics result from high launch rate, smaller, currently flying vehicles, Zubrin claims that the cost per kilogram for launching payloads is lowest with bigger systems today. On the other hand, Bonin cites the importance of high launch volumes and an anchor tenant for the launch industry as being key to driving such costs down, and to promoting better systems instead of bigger ones. Bonin also cites the critical issue of redundancy, maintaining that a larger number of smaller boosters reduces risk, whereas a program based on a single big vehicle puts its eggs in one basket.
There are other arguments that walk a middle ground, advocating a mixed fleet approach and/or the use of orbital propellant transfer to separate the issue of launch from the in-space aspects of a given mission. In such scenarios, spacecraft may be launched with a big launch vehicle to avoid orbital assembly, and then have fuel transferred to them by smaller launches.
, descent and landing
, since proven technologies do not scale well for larger payloads. Mars expeditions with humans may therefore need new technology development for the descent process. At Space Vision 2006, Bonin acknowledged this fact, stating that either Mars for Less or its parent plan Mars Direct would have to be recalculated because their original figures were overly optimistic with regard to aerocapture
.
. A modified version of the proposal was presented at the International Space Development Conference
and SpaceVision in 2006. Mars for Less was also an early mission design advocated by the space advocate group Marsdrive
. Mars for Less has also been released as an add-on for the Orbiter Space Flight Simulator.
Heavy Lift Launch Vehicle
A Heavy Lift Launch Vehicle, or HLLV, is a launch vehicle capable of lifting more mass into Low Earth Orbit than Medium Lift or Mid-Heavy Lift Launch Vehicles.There is no universally accepted capability requirements for heavy-lift launch vehicles....
s (HLLVs) that many think are required for human space exploration. While more complex than many other mission proposals, Mars for Less has strong economic arguments, including avoiding launch vehicle development costs, and offering the prospect of an anchor tenent for the currently over-supplied launch vehicle market, which could result in reduced launch costs and incentives to develop reusable launch technology. The MFL plan was developed by aerospace engineer Grant Bonin in 2003 when he was a student at Carleton University
Carleton University
Carleton University is a comprehensive university located in the capital of Canada, Ottawa, Ontario. The enabling legislation is The Carleton University Act, 1952, S.O. 1952. Founded as a small college in 1942, Carleton now offers over 65 programs in a diverse range of disciplines. Carleton has...
.
The proposal
The Mars for Less mission is heavily based on Robert ZubrinRobert Zubrin
Robert Zubrin is an American aerospace engineer and author, best known for his advocacy of the manned exploration of Mars. He was the driving force behind Mars Direct—a proposal intended to produce significant reductions in the cost and complexity of such a mission...
's Mars Direct
Mars Direct
Mars Direct is a proposal for a manned mission to Mars. Proponents of the scheme have claimed it to be both cost-effective and that it can be conducted with current technology. It was originally detailed in a research paper by NASA engineers Robert Zubrin and David Baker in 1990, and later expanded...
mission design, in which two different spacecraft
Spacecraft
A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....
are used for a single human expedition. One spacecraft (called the Earth Return Vehicle, or ERV) is sent to Mars unmanned on a trajectory similar to a Hohmann Transfer Orbit
Hohmann transfer orbit
In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbits, typically both in the same plane....
before the crew. This vehicle lands and fuels itself using a Sabatier process, creating methane/oxygen rocket fuel (bipropellant) out of carbon dioxide obtained from the Martian atmosphere and a relatively small amount of hydrogen imported from Earth. Once the ERV is fuelled, the crew is launched to Mars on a free return trajectory
Free return trajectory
A free return trajectory is one of a very small sub-class of trajectories in which the trajectory of a satellite traveling away from a primary body is modified by the presence of a secondary body causing the satellite to return to the primary body...
. The crew arrives after about 180 days and lands in the proximity of the ERV. They spend about 500 days on the surface exploring, then return to Earth in the ERV.
The Mars for Less plan is different from Mars Direct in that it uses multiple launches of existing launch vehicles, instead of a few launches of heavy lift boosters. In the MFL plan, separate components are launched individually to low-Earth orbit, where they are mated together over the course of about half a year. Each component is itself autonomous, so that only an orbital assembly, and not construction, would ideally be required. By avoiding the development of a heavy lift launch vehicle like NASA's proposed Ares V
Ares V
The Ares V was the planned cargo launch component of the Constellation program, which was to have replaced the Space Shuttle after its retirement in 2011. Ares V was also planned to carry supplies for a human presence on Mars...
, such a mission could theoretically be undertaken today.
Economic arguments
In January 2006 MFL author Grant Bonin wrote an economic argument to complement the technical discussion of MFL, titled "The Case for Smaller Launch Vehicles in Human Space Exploration". Bonin cites high flight rates of existing launch vehicles as a key driver in cost reduction, increased confidence, and in motivating the development of smaller, reusable launch systems instead of bigger expendable ones. Part 1 of this article appeared in The Space Review on January 3 2006, and Part 2 appeared on January 9, one week later.Small vs. large launch vehicles
Mars for Less addresses the issue of whether heavy-lift launch vehicles are needed for human space exploration. Whereas Robert Zubrin has long advocated the development of a new heavy launcher for any Mars expedition, Bonin's work rejects such notions. This issue is still hotly debated among space advocates.While Bonin maintains that better economics result from high launch rate, smaller, currently flying vehicles, Zubrin claims that the cost per kilogram for launching payloads is lowest with bigger systems today. On the other hand, Bonin cites the importance of high launch volumes and an anchor tenant for the launch industry as being key to driving such costs down, and to promoting better systems instead of bigger ones. Bonin also cites the critical issue of redundancy, maintaining that a larger number of smaller boosters reduces risk, whereas a program based on a single big vehicle puts its eggs in one basket.
There are other arguments that walk a middle ground, advocating a mixed fleet approach and/or the use of orbital propellant transfer to separate the issue of launch from the in-space aspects of a given mission. In such scenarios, spacecraft may be launched with a big launch vehicle to avoid orbital assembly, and then have fuel transferred to them by smaller launches.
Near term viability
Critics contend that plans like Mars for Less neglect the issue of landing larger masses, i.e. atmospheric entryAtmospheric reentry
Atmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line,...
, descent and landing
Mars landing
A Mars landing is a landing of a spacecraft on the surface of Mars. Of multiple attempted Mars landings by robotic, unmanned spacecraft, six were successful. There have also been studies for a possible manned mission to Mars, including a landing, but none have been attempted.-Mars probe program:In...
, since proven technologies do not scale well for larger payloads. Mars expeditions with humans may therefore need new technology development for the descent process. At Space Vision 2006, Bonin acknowledged this fact, stating that either Mars for Less or its parent plan Mars Direct would have to be recalculated because their original figures were overly optimistic with regard to aerocapture
Aerocapture
Aerocapture is a technique used to reduce velocity of a spacecraft, arriving at a celestial body with a hyperbolic trajectory, in order to bring it in an orbit with an eccentricity of less than 1. It uses the drag created by the atmosphere of the celestial body to decelerate. Only one pass in the...
.
Publication history
Mars for Less was first published in the September/October 2005 issue of the Journal of the British Interplanetary SocietyJournal of the British Interplanetary Society
The Journal of the British Interplanetary Society is a technical scientific journal, first published in 1934. JBIS is concerned with space science and space technology...
. A modified version of the proposal was presented at the International Space Development Conference
International Space Development Conference
The International Space Development Conference is the annual conference of the National Space Society . Now in its 30th year, these conferences connect the general public and the NSS membership with leaders of contemporary space efforts...
and SpaceVision in 2006. Mars for Less was also an early mission design advocated by the space advocate group Marsdrive
MarsDrive
MarsDrive, founded in 2005, is an international non-profit space organization with a worldwide membership and branches across North America, Europe and Australasia...
. Mars for Less has also been released as an add-on for the Orbiter Space Flight Simulator.