New Mars Forums

After more than two decades of development, it is essential that the United
States keeps the ability to visit, work and return from the ISS within its
national capabilities. Yet, it is surprising to see how little discussion,
much less pressure, is being applied to accelerating plans to regain an
independent capability for human spaceflight. Now seems to be the time for
Congress, NASA and the general public to all push hard, and get one or more
of these U.S. systems in space as soon as possible."
http://www.space.com/25785-american-hum … riott.html

It means U.S.-based commercial space transport is even more important
than ever, said Frank DiBello, president and CEO of Space Florida, an agency
behind fostering the growth of Florida's space industry.
“This type of news even further magnifies the need for the U.S. to be
aggressive about enabling commercial space market expansion ASAP. As with
transport of crews to the ISS, we cannot wait much longer. Swift action must
be taken to ensure our states and commercial U.S. companies have the tools
they need — whether that be dedicated launch infrastructure or engines — to
keep our national space program intact without reliance on others,” he said.
http://www.bizjournals.com/orlando/blog … -plan.html

To avoid reliance on good Russian–American relations, the United
States must accelerate the development of an American rocket. Bolden has
already asked for this, telling the U.S. Congress that “the choice here is
between fully funding the request to bring space launches back to American
soil or continue to send millions to the Russians.” Thus far, Congress has
not acted to accelerate the development of an American-built rocket.
http://www.themarknews.com/2014/05/13/e … options-2/

RGClark wrote:

Human 2 Mars conference April 22 to April 24 in Washington, D.C.:

http://www.eventbrite.com/event/7899049269/efblike

Keynote speech by NASA administrator Charles Bolden. I plan to attend.
Hoping to get feedback on the possibility of using using solar powered plasma drives to shorten flight times:

http://exoscientist.blogspot.com/2014/0 … sible.html

  Bob Clark

Please give us some updates on the presentations Bob - sounds like a brilliant conference.

L1 is also a possibility; there are a lot of studies of the "L1 Gateway" station, as it is called. L1 may be more convenient because it is closer and faster to reach, but it takes 300 meters per second more delta-v. Either way, trans-Earth injection has to be done deep in Earth's gravity well, so you have to go back to Earth to head to Mars. L1 is closer and more convenient.
You could also save time and propellant using a solar electric or solar thermal engine to move most of your assets into a very large elliptical orbit, then move the people and the earth return capsule there quickly, rendezvous above the Van Allen Belts, loop back in, and perform trans-Earth injection.
Personally, I rather like solar thermal propulsion. You can only generate about 100 pounds of thrust at a time, but you can heat up a transfer medium for many hours and choose when to perform your burn--at perigee--so it is efficient. It can generate specific impulses of 900 seconds, maybe more; so it is comparable to a nuclear thermal engine. But you can't use it to move people; they'd loop through the Van Allen Radiation Belts repeatedly.

Today's weather report on Mars:
http://cab.inta-csic.es/rems/marsweather.html

Air: high -22°C, low -84°C
Ground: high -7°C, low -96°C
Pressure: 843 Pa (0.843 kPa)
Sunrise 5:52am, Sunset 5:34pm local time
Sunny

Today's weather for Winnipeg:
Temperature at 6:00pm: -26.7°C, prediction for the low tonight: -33°C
Windchill: current -38, tonight's low -44
Pressure: 103.6 kPa
Sunrise 7:12am, Sunset 6:10pm
Sunny

Why not use a fold-out heat shield? I keep going back to Mars Direct. This is image is from the original 1989 proposal from Dr. Zubrin and Dr. Baker from Martin Marietta to NASA, the heat shield and landing propulsion module for Mars Direct.
http://www.wired.com/images_blogs/wired … 00x113.jpg

Interesting. The web page describes it as...

Eight months after Earth departure, the propellant factory/ERV would aerobrake into Mars orbit behind a 23-meter-diameter, 5.26-metric-ton umbrella-like ”flex-fabric” heat shield.  Soon after capture into Mars orbit, the landing propulsion module would ignite its rocket motors to decelerate the propellant factory/ERV for reentry into the martian atmosphere

From the images I had assumed it was a solid heat shield with fold-out panels. After reading about DurAFRSI from Ames Research Center, I thought it was my wonderful idea to use the fabric from DurAFRSI as a parasol or "umbrella-like" heat shield. Once again I have re-invented the wheel. So again I return to Mars Direct. My mission plan is tweaked from Mars Direct. but if you can fit a 23-meter-diameter heat shield in an 8-meter diameter fairing, then what is stopping us?

Manned Dragon is funded by NASA,  they are in control of its development schedule and the milestones that must be accomplished.  That schedule calls for first manned flight in 2017.  That's why NASA bought Soyuz rides through 2017. 
If it was just Spacex,  I'd bet that Dragon could fly manned by 2015.  They've been testing the Super Draco thrusters for it,  for some time now.  Once those are ready,  they just integrate into a capsule already designed to have them. 
It's just my opinion,  but I think that NASA's schedule is needlessly delayed by 1 to 2 years. 
GW

Robert Zubrin wrote a critique of VASIMR propulsion here:
The VASIMR Hoax
By Robert Zubrin | Jul. 13, 2011
http://www.spacenews.com/article/vasimr-hoax
The primary criticism is that it would require unrealistically lightweight nuclear propulsion. However, Zubrin doesn't even like the idea of fast propulsion to allow short travel times to Mars. He argues in favor of using 6 month or more one-way travel times to allow free return trajectories at Mars. But the health disadvantages of long travel times such as radiation exposure, bone and muscle loss, and the recently found eye damage and vision loss suggest we should investigate such short travel times.
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So it is important to note we may have a short term power source instead of nuclear power, for plasma propulsion such as Vasimr at the needed lightweight.
The key point is that the power source does not need to be nuclear. According to Zubrin's article on the Vasimr it requires a power source of 1,000 watts per kg power density. This is 100 times better than what has been done with nuclear space power at 10 watts per kg. However, it is only 10 times better than standard solar space cells at 100 watts per kg. Actually more recent space solar cells get 200 watts per kg, so it is only needs to be 5 times better than those.
Now the key fact is that solar cells can put out more power if they have more concentrated light shone on them. Estimates of how much power solar cellls put out are based on the solar insolation at the Earth's distance from the Sun. But if that light is concentrated they can put out more power. In fact some Earth solar power systems get more power by using inexpensive mirrors or lenses to concentrate light over a larger area rather than using expensive solar cells over that larger area.
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