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10kBq Jaro


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NASA Readying Mars Architecture
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NASA Readying Mars Architecture
Aviation Week & Space Technology, 04/16/2007, page 31
Frank Morring, Jr., Colorado Springs

NASA hopes to release a top-level Mars exploration plan this summerExploration, science and aeronautics managers at NASA will draw on years of studies to decide some basic questions this summer about how humans can travel to Mars.Doug Cooke, deputy associate administrator for exploration, says a broad architecture for Mars missions should be ready by August, addressing such issues as the optimum duration of a mission that will help planners set requirements for the hardware to carry it out.The work will stem from design reference mission concepts developed in past Mars exploration studies, as the lunar-exploration strategy NASA unveiled last December did. That approach called for using the planned Ares I and heavy-lift Ares V launch vehicles to build a permanent outpost at one of the lunar poles that would take advantage of long periods of daylight for solar power (AW&ST Dec. 11, 2006, p. 24)."Given the existence of the Ares V and the Orion crew vehicle, we're asking ourselves what more do we need than that for a mission to Mars, how should we conduct that, when could it be conducted, what needs to be developed, what would be the goals of the first expedition?" says Administrator Michael Griffin, who spoke to reporters at the National Space Symposium here.For the Mars planning, exploration managers are working with their operations, science and aeronautics counterparts to determine where to land on Mars, what science to do on arrival, what kind of power source to use and how much reliance to place on local resources for life support and return-trip fuel. They hope to get some of the big questions answered by this summer, and one of the biggest and most basic is just how long a mission should last. Cooke says that decision will be based on well-understood trajectories based on the relative positions of Earth and Mars. Using today's technology, a 500-day mission would require 240 days to return, leaving only 30-40 days for surface exploration. A 1,000-day mission would shorten the debilitating cruise time between the planets to about 180 days each way, but would require the explorers to remain on the surface of Mars for almost two years.Feeding into the duration decision will be fuel-consumption calculations and the anticipated difficulty of making equipment reliable enough to handle the different time periods, Cooke says. Scientific results from robotic Mars orbiters and landers will play into the results, as will space-operations considerations and plans to learn more about the Martian atmosphere from instruments to be placed on the heat shield that will protect the Mars Science Laboratory set for a 2009 launch.Also under study is what can be done on the Moon to prepare for Mars, including working in fractional gravity, heavy ion radiation studies and learning to live for an extended period on another planetary surface."Those are things we'll be doing on the Moon to feed the next step to Mars," says Griffin, who stresses that choices made this summer will not be "decisive" for Mars missions to be launched in 2027 or beyond. Instead, they will be "vectors, or point-aheads" from the return to the Moon planned by 2020. Some of the work must await mapping data to be returned by Japan's Selene lunar orbiter after its planned launch this summer and by NASA's Lunar Reconnaissance Orbiter and India's Chandrayaan-1 to launch next year. NASA wants to place the outpost where it can receive maximum light for solar power. Although early planning work has focused on the rim of the Shackleton Crater at the Moon's south pole, there is a suggestion that sites at the north pole may get more light (AW&ST Mar. 19/26, p. 48). The Moon's polar regions have not been mapped as extensively as equatorial regions, but by the time the coming wave of lunar orbiters is over that situation should be remedied.Just as the site of the first outpost will be determined in part by the international flotilla of lunar orbiters, so will the facilities at that site be shaped by an international agreement on cooperation in human lunar exploration nearing completion. Adopted in draft form in Kyoto, Japan, last month, the "framework agreement" for international lunar exploration should get final ratification from all 14 parties by Apr. 30.Kaoru Mamiya, vice president of the Japan Aerospace Exploration Agency (JAXA), says his agency hopes to piggyback on the lunar transportation architecture NASA is developing to send its own astronauts to the Moon after 2020. In an address to the space symposium, Mamiya says Japan wants to follow the precedent set on the International Space Station by contributing facilities for the lunar outpost--power systems rank high on the Japanese list--in exchange for transportation to the Moon. "Space is the common frontier of humanity," Mamiya says. "International cooperation in space exploration is essential." NASA's work on the Orion crew exploration vehicle and its Ares I launcher continues on schedule for now, although Griffin has told Congress that cuts to NASA's budget under the Fiscal 2007 funding resolution will likely force a slip for its initial operational capability into 2015.Cooke says the contract for the Ares I upper stage production should be awarded to a team led by ATK or Boeing by fall, and the one for the rocket's instrument unit by December. The bidding process for the upper stage, to be built to government design at NASA's Michoud Assembly Facility in Louisiana, is wrapping up, and the request proposals for the instrument unit containing the vehicle avionics are expected in June.Ares I's largest obstacle will be delivery of Pratt & Whitney Rocketdyne's (PWR's) J2-X upper-stage engine. Cooke says that the Saturn-heritage J2-X essentially will be a new engine requiring a full-test regimen to qualify it for human spaceflight. So far, upgrading is going well, says Walt Janowski, deputy program manager for the J2-X at PWR. Preliminary design review is scheduled this summer, and the engine's power pack is due for a first round of testing at Stennis Space Center this fall.


-- Edited by 10kBq Jaro at 01:36, 2007-04-17

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10kBq Jaro


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I thought it interesting that the Aviation Week article above didn't mention the N-word.
Well this one does -- as any article having to do with travel to Mars should.
Have you seen any others ?

http://www.flightglobal.com/articles/2007/04/16/213243/nasa-aims-to-finish-manned-mars-mission-study-by-august.html  
NASA aims to finish manned Mars mission study by August
By Rob Coppinger

NASA will have a basic architecture for a manned Mars mission in late July, says NASA deputy associate administrator for exploration systems Doug Cooke.The Mars work began in January and will build on previous design reference missions produced by NASA. What differs with this study is that the performance specifications of the Ares I crew launch vehicle and Ares V heavy lift vehicle will play a large part in the analysis."It wont be as detailed as the [2005] Exploration Systems Architecture Study [that dealt with the Moon]," says Cooke.However it will draw conclusions about whether NASA wants to carry out long or short stay missions to Mars, what surface power supply would be used, and what propulsion is required. At the moment NASA envisages a Marsship that is as large as the International Space Station and uses either nuclear or solar electric propulsion systems.

Cooke added that NASAs aeronautics centers were interested in working on the dynamics of Mars atmospheric entry. Last year NASA administrator Michael Griffin announced that Mars mission studies would be undertaken this year.



-- Edited by 10kBq Jaro at 01:37, 2007-04-17

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GoogleNaut


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Well, personally, I think it would not only be silly, but irresponsible to send a crew to Mars without also sending the means to keep them alive. A nuclear power plant, even a small one, could supply sufficient power and heat, even during darkest days of a global dust storm, to keep a small base running.

The cooling tower or radiator could be peridically cleared of dust simply by blowing high pressure CO2 onto its surfaces--a small compressor could easily take in the thin local atmosphere and compress it into a liquid in a storage tank.

Solar cells could be cleared in similar manner, of course, but there will be more acreage. And during a dust storm their collection efficiency will plummet quite a bit, especially if the cells become covered.

A small nuclear plant is really the only realistic and responsible choice to power a Mars Base. And I would take that assertion to the bank!



-- Edited by GoogleNaut at 05:26, 2007-04-17

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Andrew


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Not to mention the fact that solar's power per square meter is around 1/3rd of Earth's and the small fact that expensive and sensitive solar panel's won't take well to Mars's harsh dust.

Something similar goes for using solar thermal, low energy, has practical problems (I recall that a Mars Surveyor went offline when not correctly aligning surwards) and there is the small fact that performance is smaller compared to ion or even VASIMR drives. Any crew signing off for such a mission would be signing off their death warrant.

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10kBq Jaro


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Andrew wrote:

Not to mention the fact that solar's power per square meter is around 1/3rd of Earth's

Maybe this could solve the problem (for both surface power AND transportation)  :

http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=818  http://space.com/businesstechnology/technovel_mars_061118.html

Space Mirrors May Create Martian 'Pocket-Eden'
By Bill Christensen
posted: 18 November 2006

One of the problems that explorers on Mars will face is low surface temperature. Although the surface temperature on Mars can rise above freezing in the summer, the mean temperature is about -60°C (-90°C at night). Mars' orbit is highly elliptical which leads to even greater cold in winter - temperatures as low as -110°C on the poles. Rigel Woida, an engineering student at Arizona State University in Tucson, has been awarded a $9,000 NIAC (NASA Institute for Advanced Concepts) Student Fellows Prize to study the use of large orbital mirrors to heat a small area of the Martian surface. Raising the temperature in a 150 acre patch would make it easier and more economical for humans to study the Red Planet.

Woida's prize-winning project is titled "The Road to Mars." Optical sciences Professor Eustace Dereniak and Assistant Research Professor Robert M. Stone will supervise Woida on the project.

Orbiting balloons made of a reflective metallized polyester would act as mirrors, collecting sunlight and shine it down to the Martian surface.

http://space.newscientist.com/data/images/ns/cms/dn10573/dn10573-1_800.jpg

"I adjusted the aperture so the reflector would heat ... (the) surface to roughly Tucson daytime illumination and temperatures, said Woida. "Eventually, using techniques like these, humans might cultivate plants on Mars."

The higher temperatures would allow astronauts to survive without heavily insulated suits or living quarters, increasing comfort while reducing costs. Added sunlight would increase output from solar power cells on the surface; it might also melt ice at or just below the surface, making it available for human use.

Although still a student, Woida is no stranger to scientifc achievement. In high school, he was the driving force behind the construction of Tucson High Magnet School's thirty-inch telescope. After coming up with the idea, he successfully raised the necessary financial support from the school district, a private laboratory and the University of Arizona.

There is a rather unusual precedent for this idea in science fiction. Fallen Angels, a 1991 novel written by Larry Niven, Jerry Pournelle and Michael Flynn, contains a scene in which people are fleeing across a glacier without the necessary equipment to survive the -30 degree (F) temperatures. They survive by having a satellite focus a "spotlight" of solar-generated microwave energy onto their location:

"Big Momma, it's cold here. We're going to freeze, all of us. We need heat. Can you give us a microwave spotlight? Have SUNSAT lock one of its projectors onto our transponder frequency and track us across the ice."

"Skazhiyte. One moment." Alex waited while Big Momma conferred - probably with the Peace Station chief and the SUNSAT engineer. Sherrine asked him what he was doing and he told her...

"Is that possible?" she asked. "To beam enough microwave energy down to keep us from freezing? ...It won't be too much, will it?"

Alex grinned. "I'll have them set it for thaw, not bake...

(Read more about Spotlight of Heat http://www.technovelgy.com/ct/content.asp?Bnum=1143  )

Woida's plan is also not without potential hazards; the mirrors could focus harmful high-frequency radiation like gamma rays onto the surface. This problem might be solved by using a coating on the balloons that reflected only visible and infrared light, says Woida.



-- Edited by 10kBq Jaro at 20:37, 2007-04-17

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Andrew


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Not new idea, and even if it would work, you will need to make a giant mirror in geosynchronous orbit around Mars, something more difficult then simply pack up some RTG's and extra shielding.

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The space mirrors around Mars isn't such a bad idea. Infact, once there are colonists on Mars, this would be an excellent way to suppliment the sunshine that they would already get. A space mirror some tens of kilometers on a side, aimed as a spacebased heliostate, could provide a decent sized domed city on Mars with enough additional sunlight to approach Earth insolation levels--this should infact provide more than adequate light for growing crops, keeping warm, and even generate some additional power.

I'm sure that such a thing will be obvious to colonists living on Mars--once they get there.

But still, I'll bet they will still want an 'Old Faithful' fission reactor for backup power--just in case!


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Andrew


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I'd rather use the mirrors to melt the ice caps.

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10kBq Jaro


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GoogleNaut wrote:

A space mirror some tens of kilometers on a side, aimed as a spacebased heliostate, could provide a decent sized domed city on Mars with enough additional sunlight to approach Earth insolation levels--this should infact provide more than adequate light for growing crops, keeping warm, and even generate some additional power.

I wonder what the minimal size of such a mirror would be -- both in area and in mass -- to serve an early Mars base.
According to the above linked concept, its supposed to be an inflatable structure.
Potentially, with very thin membranes, this could be very lighht -- perhaps light enough to deliver complete from Earth ?
As for development, its possible that it may soon be aided by the US military -- reports of their interest in "solar power satellites" have recently appeared in the press.
But I suspect that rather than "solar power" they may just be interested in sun mirrors, as weapons of war against terrorists :
Illuminating a terrorist camp in the middle of night, just before attack, or in the middle of a hot day -- adding a second sun, as it were -- could be an effective tool.


As for the Mars mirror, anyone know what the radius is for a Mars-stationary orbit ?
One would think that with days about the same length as Earth, and a much lower gravity field, it should be much closer in than geostationary orbit.....



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Andrew


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What I would like to see is how will they prevent the giant mirror from turning it into a giant solar sail.

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O.K., doing a little digging, I found that the Mars rotational period is 24.622962 hr, according to http://en.wikipedia.org/wiki/Mars

We'll call P the orbital period of some orbit about Mars, and set it to: 88642.7 seconds, Mars' rotational period.

Mars' mass from the same source is about: 6.4185×10^23 kg

From first principles the mean orbital speed of an object that has neglible mass compared to the parent body can be found from:

V(r) = sqrt(G*M/r) where V(r) is the mean orbital speed of a circular orbit in m/s, M is the mass in kilograms of the central body, G=Newtons Gravitational Constant 6.672^10^-11 N*m^2/Kg^2

The circumference of a circular orbit is simply found from:

C(r) = 2*pi*r

and the period of a circular orbit at radius r is simply found from:

P(r) = C(r)/V(r)

Now substituting for C(r) and V(r) and doing some algebra we get:

P(r) = 2*pi/sqrt(G*M)*r^(3/2) solving for r in terms of P and cleaning up the mess algebraicly will thus give:

r(P) = (G*M*P^2/(4*pi^2))^(1/3)

To find the aerosynchronous orbital radius, it is sufficient to substitute P=88642.7 seconds for the orbital period, M=6.4185×10^23 kg, and G as before will give:

r = 20427.6 km. This is the orbital radius from Mars' center to a Aerostationary Orbit about Mars.

Mars has an equatorial radius of 3402.5 km, so the orbital height is about: 17,025 km!

Neet problem!

-- Edited by GoogleNaut at 01:26, 2007-04-22

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10kBq Jaro


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Great stuff, Ty -- I should have guessed you'd do another "first principles" demonstration !

Thanks !

....the 17,025 km altitude for Mars is less than half of Earth's 35,786 km -- impressive !
....its also a bit lower than the altitude of Mars' outer moon Deimos ("the orbital period of Deimos of about 30.4 hours exceeds the Martian solar day").

Anyway, that ought to make it a bit easier to put effective solar mirrors in Martion synchronous orbit, than Earth's.

I suppose that in the distant future, Deimos could become a convenient source of raw materials for truly gigantic solar mirrors, serving large Martian colonies -- akin to desert cities like Phoenix or Tucson.

Where in Mars' equatorial region would you prefer to locate the first such city ?

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Some place with warm, clear blue seas, tropical breezes, swaying palm trees, and stunning native princesses should do quite nicely...er, but I digress!

I would imagine that a detailed gamma-ray spectroscopy scan of Mars should find near surface deposits of ice, and or subsurface aquifers. Anyplace that offers reasonably stable ground, access to Martian water, and of course access to plenty of solar energy.


-- Edited by GoogleNaut at 00:55, 2007-04-23

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