Abbreviations and acronyms

AEDL Aero Entry, Descent, and Landing (the process of using a aerodynamic forces to decelerate spacecraft at Mars or Earth for orbit insertion or descent) AIAA American Institute of Aeronautics and Astronautics ALARA As Low As Reasonably Achievable (refers to a philosophy for controlling radiation to astronauts) ALS Advanced Life Support (NASA program to develop advanced systems for life support) Am Amorphous AS Ascent Stage (propulsion stage to ascend from Moon or ASEE American Society of...

Mass and power requirements of a Mars ISRU system

The data in this section are based on a joint JPL Lockheed-Martin Study in 2004-2005 (to be referred to as JPLMS).108 The system being modeled here utilizes the following elements Water is obtained from near-surface regolith containing 10 water by weight. The Sabatier Electrolysis process is used. C02 is acquired by a cryogenic freezing process. ISRU is carried out in a 16-month cycle to produce 10 mT of CH4, 35mT of propellant oxygen, 5mT of consumable oxygen, and 108 mT of water. Propellant...

Solar electric propulsion for orbit raising

One of the major requirements for propellants in any space exploration venture is for departing from the gravitational influence of the Earth. While most mission concepts call for an Earth departure propulsion stage to fire up in LEO, another conceivable alternative is to use solar electric propulsion to raise the orbit of the spacecraft from LEO to a high Earth orbit, and thereby greatly reduce the propulsion requirements for Earth departure from this high orbit that is outside most of the...

Mars ISRU products

A vital ISRU product of relevance to Mars missions is oxygen for use as a propellant in ascent from Mars. This oxygen would be stored as a cryogenic liquid in the Mars Ascent Vehicle. The amount of oxygen required will depend on several factors (1) the mass of the capsule to hold the crew during ascent and rendezvous, (2) the number of crew-members, (3) the orbit in which rendezvous takes place, and (4) the fuel propellant used in conjunction with the oxygen. In a typical rocket using oxygen as...

Radiation effects on humans and allowable dose 4231 Allowable exposure

Because the biological effects of exposure to space radiation are complex, variable from individual to individual, and may take years to show their full impact, definition of allowable exposure will always include some subjectivity. Aside from the difficulty in quantifying the biological impacts of exposure to radiation in space, there is also subjectivity in defining how much risk is appropriate. Presently, there are no guidelines for allowable radiation exposure in deep space. A common...

Why explore Mars

1.1 ROBOTIC EXPLORATION THE ESTABLISHMENT'S VIEW JPL manages the NASA Mars Exploration Program (MEP) for NASA. This Program has been carrying out a series of robotic missions for a number of years to explore Mars. The great success of the Mars Pathfinder and Mars Exploration Rover missions has shown that autonomous rovers can traverse the surface of Mars and make important scientific observations within limited areas. As a result, an ambitious long-range plan for in situ exploration has been...

Oxygen from regolith silicates

Lunar ISRU based on extraction of oxygen from regolith has two advantages (1) Regolith is typically > 40 oxygen. (2) Regolith is available everywhere and solar energy may be feasible for processing. Unfortunately, the oxygen in regolith is tied up in silicate bonds that are amongst the strongest chemical bonds that are known, and breaking these bonds inevitably requires very high temperatures. JSC is currently interested in the carbothermal process. This concept is based upon a...

Space Science Enterprise SSE 8411 SSE scope of technology

One could imagine two extreme positions that NASA might take on advanced technology. On the one hand, NASA could take a narrow point of view that it is an organization dedicated to developing spacecraft for exploration of space, and emphasize technologies of importance to space missions, regardless of the world movements and trends in technology. On the other hand, there is a danger of NASA developing the best spacecraft, but filled with obsolete technology. For the world as a whole, the...

Radiation in space

A number of point estimates of radiation doses in various locations with various levels of shielding are presented in the literature. Figure 4.2 shows the effect of shielding on GCR. Moderate amounts of shielding are beneficial in reducing the lower energy components of GCR, but, as more shielding is added, diminishing returns result 57 Analysis of Lunar and Mars Habitation Modules for the Space Exploration Initiative (SEI), L. C. Simonsen, Chapter 4 in Shielding Strategies for Human Space...

Onorbit staging

A recent published paper119 describes a concept called on-orbit staging'' (00S) that the authors believe is critical to achieving the objectives of the human exploration initiative. The authors say We demonstrate with multiple cases of a fast (< 245-day) round-trip to Mars, that using 00S combined with pre-positioned propulsive elements and supplies sent via fuel-optimal trajectories can reduce the propulsive mass required for the journey by an order-of-magnitude.'' The authors thereby imply...

Michael Griffin and orbiting fuel depots

In a presentation112 given in November 2005, the NASA Administrator, Dr. Michael Griffin, said our mission architecture hauls its own Earth-departure fuel up from the ground for each trip. But if there were a fuel depot available on orbit, one capable of being replenished at any time, the Earth departure stage could after refueling carry significantly more payload to the Moon, maximizing the utility of the inherently expensive Shuttle-derived heavy lift vehicle (SDHLV) for carrying high-value...

Zero boiloff systems

Basically, there are two approaches for cryogenic storage in space 1 Use a larger tank and allow boil-off, so that the desired amount of hydrogen is available at the end of storage duration. 2 Use a tank that contains the ultimate amount of hydrogen needed from the start, and provide an active cooling system to remove an equivalent amount of heat that continually leaks in during the storage period, thus avoiding boil-off. This is called the zero boil-off ZBO approach. The ZBO approach...

Getting there and back

While there are many challenges involved in planning human missions to Mars, the problems involved in launching, transporting, landing, and returning large masses from these bodies appear to be perhaps the most formidable of these hurdles. In a round-trip human mission to Mars or the Moon, there are a number of steps that must typically be traversed Trans-Mars injection from LEO Earth orbit departure . Entry, descent, and landing at Mars. Trans-Earth injection Mars orbit departure . Entry,...

Gear ratio calculations

All previous NASA design reference missions for human missions to Mars involved transfer of some assets mass MM0 to Mars orbit, and some assets to the Mars surface mass MMS . The optimal choice of the Mars orbit depends on 1 whether in situ resource utilization ISRU is used to produce ascent propellants from indi genous resources, and 2 the relative values of Mmo that dictate propellant requirements for orbit insertion and departure, and the mass of the Ascent Capsule that determines the mass...