Saturday, August 9, 2014

Thursday, July 31, 2014

Thursday, July 10, 2014

Landing Large Cargos and Crews on the Surface of Mars

Tethered beneath a hydrogen inflated ballute, a crewed  Ares 2 (Ares ETLV-2) reusable landing shuttle slowly descends towards the martian surface.






















Launching human crews from the surface of the Earth to low Earth orbit (LEO) requires a delta-v of more than 9.3 kilometers per second (km/s). But on the Moon and Mars, the delta-v requirements are significantly lower. Launching humans from the surface of the Moon to lunar orbit can require as little delta-v as 1.87 km/s. And launching human crews from the surface of Mars to low Mars orbit requires a delta-v of only 4.4 km/s.

Landing humans on the surface of the Earth and on the Moon is relatively easy. Only minuscule amounts of delta-v are required to for crews to  leave Earth orbit and glide or parachute through the Earth's thick atmosphere to the terrestrial surface. The delta-v required to land a crew on the surface of the Moon from lunar orbit is equivalent to the delta-v required to leave the lunar surface to low lunar orbit.

Unfortunately,  landing crews and large payloads on the surface of Mars  is much more problematical. The largest spacecraft that NASA has managed to safely  deploy to the Martian surface are all below 600 kilograms in mass. The weight of a lunar derived crewed vehicle to the Martian surface is likely to weigh as much as 10 tonnes, not including the substantial amounts of fuel  needed to return to orbit around the Red Planet. And NASA eventually wants the ability to  deploy as much as 100 tonnes of payload onto the martian surface by a single spacecraft. 



Notional ballutes designed to aerobrake into a planetary orbit or to land on the surface of Mars (Credit: NASA)

 The problem with landing large masses on the surface of Mars is that even though the martian atmosphere is approximately 1% as dense as the Earth's atmosphere, it's still thick enough to produce substantial amounts of frictional heating as a vehicle plunges at hypersonic speeds through its atmosphere  but still not enough friction to sufficiently lower the terminal velocity as it approaches the planet's surface. Small vehicles (less than 600 kg) attempting to land on Mars have, therefore, been designed to have a high  drag coefficients. Designing a spacecraft with a high drag coefficient for vehicles weighing several tonnes or more, however, is much more difficult.

This has pushed NASA towards the idea of utilizing large inflatable ballutes to assist heavy payloads and spacecraft entering the martian atmosphere. The large drag coefficient of a toroidal ballute could allow a spacecraft to decelerate at very low densities high in the martian atmosphere with relatively low rates of frictional heating.  The low frictional heat experienced by the ballute could allow for light-weight construction techniques that could enhance the ability to deploy more mass to the martian surface. Ballutes inflated with gases that are lighter than the carbon dioxide could also increases static lift. Recent studies  suggest that a toroidal ballute with a tube radius of 80 meters could be used to deliver masses the martian surface of approximately 100 tonnes.

Top: ETLV-2 vehicle designed for landing on the surfaces of the Moon and  the moons of Mars; Bottom: An ETLV-2 derived Ares 2 vehicle designed to dock with a disposable heat shield  and compacted ballute in order to land on the surface of Mars.
Placed on the surface of Mars, a single staged reusable vehicle with an inert weight of approximately 10 tonnes (including payload and crew) designed to travel to and from the lunar surface would require at least 18 tonnes of fuel to transport a crew from the martian surface to low Mars orbit;  22 tonnes of fuel  would be required to reach the surface of Phobos and  24 tonnes of fuel would be needed to reach the surface of Deimos from the martian surface. So with a delta-v requirement of less than 5.3 km/s, a fueled  single staged crew vehicle weighing nearly 40 tonnes placed on the surface of Mars should be capable of  traveling all the way from the martian surface to the surface of Deimos or to high Mars orbit.
 

Left: Ares 2 docked with a compacted (pre-deployed) ballute, configured to  inject the spacecraft towards an aerobraking encounter with the martian atmosphere.  Right: After the rocket burn towards Mars, the Ares 2 would reconfigure itself in order to protect the spacecraft and to inflate the ballute in order to aerobrake and to descend through the martian atmosphere.

A liquid hydrogen and oxygen producing water and fuel depot derived from a reusable orbital transfer vehicle. The Ares 2 landing vehicle would fuel up up at the orbital depot before docking with the compacted ballute/heat shield unit.  Water would be transferred to the fuel depot from water factories on  the martian moons, Deimos and Phobos.


Water factory would utilize mobile microwave water bugs to extract water from the regolith of the martian moons, Deimos and Phobos; WFD-LV would convert water into fuel to launch water to fuel manufacturing depot in high Mars orbit.

A  ballute capable of deploying nearly 40 tonnes to the martian surface could also easily deploy habitats and cargo larger than those contemplated for the Altair vehicle  to the lunar surface. Cargo missions to the martian surface could utilize ballutes to deploy mobile robots  for excavating and sintering the surface of Mars to create landing and launch pads for crewed shuttle vehicles and for regolith shielded outpost similar to those that could be utilized on the lunar surface.


Hydrogen inflated ballute would enable the crewed Ares 2 vehicle to aerobrake and land on the martian surface.
Small nuclear reactors would also need to  be deployed to power the martian outpost at night or during periods when sandstorms block out significant amounts of sunlight.  Methanol/oxygen fuel cell electric power plants could also be deployed as back up power, utilizing methanol produced from the pyrolysis of human biowaste and oxygen extracted from atmospheric carbon dioxide or from the electrolysis of water.

Water factories than mine water from the martian regolith would also need to be deployed. Mobile microwave robots  could be used to melt the ice contained in the martian regolith. Water, of course, is essential for drinking, washing, and growing food but is also essential for the production of oxygen for air. Hydrogen and oxygen can also be used to produce hydrogen and oxygen to fuel the reusable shuttle craft.

Ares 2 hovers near the sintered landing area of a martian outpost.
Under the scenario presented here, fuel depots and rotational human outpost would already be placed in high Mars orbit a few years before the first crewed missions to the martian surface along with water and fuel producing facilities on the surface of the martian moons, Deimos and Phobos. Human interplanetary missions to Mars orbit would utilize an orbital transfer vehicle operating between the Earth-Moon Lagrange points and high Mars orbit.
Rotating regolith shielded (enriched with iron ore) SLS fuel tank derived artificial gravity habitat in high Mars orbit capable of housing as many as 16 astronauts.

Such an interplanetary orbital transfer  vehicle would utilize fuel manufactured from water exported from the lunar poles  when going to high Mars orbit and fuel manufactured from water from the martian moons when returning to cis-lunar space. Such crewed missions would already transport  reusable Ares ETLV-2 vehicles to Mars orbit for docking with orbiting space habitats or transferring crews to the surface of the moons of Mars. A single SLS launch could deploy one or two compacted ballutes plus heat shields to high Mars orbit  for one or two human missions to the martian surface.

Three solar powered regolith shielded habitat modules joined together by two inflated corridors. Additional power for the outpost would be provided by a couple of small nuclear reactors buried beneath the regolith, a few hundred meters away.
The Ares ETLV-2 (Ares 2)  would fuel up in high Mars orbit at a OTV derived fuel depot before docking with a ballute/heat shield unit. The Ares ETLV- 2 would thin boost the Mars landing vehicle towards Mars. During the short journey from high Mars orbit towards Mars, the Ares 2 would reconfigure itself while also deploying the ballute. The ballute would allow the Ares 2 to aerobrake into orbit around Mars and then descend into the martian atmosphere. The final vertical descent to the martian surface would first drop off the protective heat shield, allowing Ares 2 rockets to slow down the final descent to the sintered surface of a martian outpost.

Ares 2 (Ares ETLV-2) about to be fueled for take-off by a mobile LH2/LOX cryotanker.


Links and References

The Mars Landing Approach: Getting Large Payloads to the Surface of the Red Planet

DUAL-USE BALLUTE-BASED ROBUST AEROCAPTURE, EDL, AND SURFACE EXPLORATION ARCHITECTURE FOR MARS.

Summary of Ultralightweight Ballute Technology Advances

A Survey of Ballute Technology for Aerocapture

TRAJECTORY AND AEROTHERMODYNAMIC ANALYSIS OF TOWED-BALLUTE AEROCAPTURE USING DIRECT SIMULATION MONTE CARLO

An Evaluation of Ballute Entry Systems for Lunar Return Missions

THEORETICAL OBSERVATIONS OF THE ICE FILLED CRATERS ON MARTIAN MOON DEIMOS

SLS Fuel Tank Derived Artificial Gravity Habitats, Interplanetary Vehicles, & Fuel Depots

Pioneering and Commercial Advantages of Permanent Outpost on the Moon and Mars 

Utilizing the SLS to Build a Cis-Lunar Highway



Tuesday, June 24, 2014

Pioneering and Commercial Advantages of Permanent Outpost on the Moon and Mars

Twin Regolith shielded habitats on a sintered  lunar surface area. Each habitat module is connected to each other by an inflatable pressurized  walkway. 
Permanent outposts on the surfaces of the Moon and Mars  could be the first major steps towards the expansion of human civilization into the rest  of the solar system.  Unaided traction for human walking requires a gravity that is at least 10% of the gravity at the  Earth's surface. The Moon, Mars, Mercury, and the Jovian moon, Callisto, are all worlds that have surface gravities higher than 0.1 g. So these are extraterrestrial worlds  that will probably be accessible for continuous human occupation before the end of the century. However, whether such  low gravity environments would  have significant deleterious effects on  human health and reproduction is currently unknown. But long before the permanent settlement of extraterrestrial worlds,  human outpost on the Moon and Mars, could have beneficial scientific, commercial, and even strategic benefits for those nations and businesses that dare to venture there.

Planets and Moons within the solar system that are potentially suitable for human colonization:

Moon

surface area relative to the Earth: 7.4%     

surface gravity relative to the Earth: 0.17g 

diameter relative to the Earth: 27.3%


Mars

surface area relative to the Earth: 28.4%
   
surface gravity relative to the Earth: 0.38g 

diameter relative to the Earth: 53.1%


Mercury
 
surface area relative to the Earth:  14.7%
   
surface gravity relative to the Earth: 0.38g 

diameter relative to the Earth:  38.3%


Callisto 

surface area relative to the Earth:  14.3%
   
surface gravity relative to the Earth: 0.13g 

 diameter relative to the Earth:  37.8%

Note: Land area comprises 29% of the Earth's surface with 71% covered by water

Regolith shielded habitat designed for the Moon and Mars. Mobile water tanker provides water to the habitat for drinking, washing, growing food, and for the production of air.
Internal view of a regolith shielded habitat with regolith placed within the two meter cavity within the automatically deployed walls surrounding  the 8.4 meter in diameter pressurized habitat.

Permanent outpost on the surface of the Moon could immediately exploit lunar regolith to protect humans from significant exposure to harmful levels of radiation.  Just two meters of lunar regolith dumped within the walls of a lunar regolith habitat could reduce annual cosmic radiation exposure below the maximum legal limit for radiation workers on Earth (5 Rem per year)  during the solar minimum while also protecting astronauts from radiation exposure from major solar events. Protection from micrometeorites and extreme temperature fluctuations would be an added benefit of  insulating a lunar habitat with regolith.

A single lunar habitat derived from the technology used to make the light weight 8.4 meter in diameter hydrogen fuel tanks for the SLS could provide two levels of floor space  approximately 111 square meters in area. That would be more floor space than the average home in Germany, Japan, Sweden, Italy, Spain, Russia, and in the UK. The deployment of such  habitats for the private commercial community could also be used  as lunar hotels for space tourist or to house workers for private companies involved in the export of lunar water or regolith for government and private entities.

Creating solid pavement for the deployment of  habitats and other lunar outpost components upon dust free surfaces could be created by using mobile robots to pave and sinter lunar regolith.  This could eliminate tracking in deleterious lunar dust into pressurized habitats when astronauts are working in the paved  lunar outpost area. 

Mobile water tanker for storing and transporting water and a mobile water extracting  robot that uses microwaves to extract water from regolith from the shadowed areas of the lunar poles.
In the lunar polar regions, roving microwave water extraction robots could mine ice particles from the  permanently shadowed areas for the production of water. Water, of course, can be used for drinking, washing, food preparation, and for growing food. Water can also be electrolyzed for the production of oxygen for air and for the production of hydrogen and oxygen for rocket fuel needed to return to Earth.

Human biowaste could be converted into methanol through pyrolysis. Methanol and oxygen can be used with fuel cells to produce electricity for back up energy during periods of lunar darkness. The water produced from the combustion of methanol and oxygen can be recycled. The CO2 produced from the manufacture of methanol and from the combustion of methanol in fuel cells can be used to enhance the growth of indoor lunar crops. Small portable methanol fuel cells could also be used to provide power for pressure suits during lunar excursions.

Nitrogenous biowaste, such as urine, could be used as fertilizer for lunar crops.

However,  there is some  evidence that substantial quantities of carbon and nitrogenous material may also  be a significant component of the permanently shadowed areas at the lunar poles. Astronauts stationed at  lunar outpost at the lunar poles could used to explore and to quantify the amount of volatiles located within the shadowed regions.

Buried nuclear power plant on the lunar surface (Credit: NASA)
While solar panels attached to the habitats would provide the initial power for a lunar habitat, small nuclear reactors   buried beneath the lunar regolith only a few hundred meters away could provide substantial amounts of electricity for the lunar facility, 24 hours a day.

Outposts originally designed for the lunar surface could also be utilized  on the surfaces of Mars, Mercury, and Callisto and even on the meager surfaces of large asteroids and on the moons of Mars.
Three regolith shielded habitat modules on a sintered  Martian surface area. Each habitat module is  connected to each other by two inflatable pressurized  walkways.   


Permanent outpost on the Moon and Mars and on other worlds, would allow the continuous exploration of those surfaces by both humans and robots. Unmanned solar or nuclear powered rovers on the lunar surface, operated by humans on Earth, could visit and collect samples from  practically every area on the surface of the Moon. The collected rocks and soil could then be returned to the lunar outpost for immediate study or for eventual export back to Earth.

On Mars, both robotic rovers and hydrogen blimps could be utilized to continuously explore the Martian surface. Such robots could be operated in real time by the astronauts on the Martian surface or in orbit around Mars at a  space station.  Again, the collected samples by the remote controlled robots could be returned to the Martian outpost for immediate study or for eventual export back to Earth.

A permanent US government presences on the surface of the Moon and Mars will also enhance the ability of private American companies to protect their assets from potentially hostile foreign entities that will probably also be on these new worlds by mid century.

Marcel F. Williams

© New Papyrus


Links and References

 D. Bryant Cramer.  "Physiological Considerations of Artificial Gravity."  Applications of Tethers in Space, volume 1, pages 3·95-3·107.  Edited by Alfred C. Cron.  NASA Scientific and Technical Information Branch, 1985.  Conference Publication 2364: proceedings of a workshop held in Williamsburg, Virginia, June 15-17, 1983.

Lunar Station Protection: Lunar Regolith Shielding

Wet vs Dry Moon

Utilizing the SLS to Build a Cis-Lunar Highway

Cosmic Radiation and the New Frontier

NASA Steps Closer to Nuclear Power for Moon Base

How big is a house? Average house size by country
 
Mission and Implementation of an Affordable Lunar Return (Spudis & Lavoie) 

Using the resources of the Moon to create a permanent, cislunar space faring system (Spudis & Lavoie)



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