Exoscientist

Nice video but I don't think nuclear rockets launched from Earth would have been acceptable. Perhaps if we had space stations on the Moon such vehicles could be launched from there. Bob Clark

Newbie here just learning to use the forum. I teach math at an east coast U.S. university. How do I change my profile and signature? I get an error message that it's not authorized. Bob Clark

I was trying to get a lower roundtrip delta-V for lunar missions by flying directly to the lunar surface rather than going first into lunar orbit then descending, the "direct descent" mode. Here's a list of delta-V's of the Earth/Moon system: Delta-V budget. Earth–Moon space. http://en.wikipedia.org/wiki/Delta-v_budget#Earth.E2.80.93Moon_space If you add up the delta-V's from LEO to LLO, 4,040 m/s, then to the lunar surface, 1,870 m/s, then back to LEO, 2,740 m/s, you get 8,650 m/s, with aerobraking on the return. I wanted to reduce the 4,040 m/s + 1,870 m/s = 5,910 m/s for the trip to the Moon. The idea was to do a trans lunar injection at 3,150 m/s towards the Moon then cancel out the speed the vehicle picks up by the Moons gravity. This would be the escape velocity for the Moon at 2,400 m/s. Then the total would be 5,550 m/s. This is a saving of 360 m/s. This brings the roundtrip delta-V down to 8,290 m/s. I had a question though if the relative velocity of the Moon around the Earth might add to this amount. But the book The Rocket Company, a fictional account of the private development of a reusable launch vehicle written by actual rocket engineers, gives the same amount for the "direct descent" delta-V to the Moon 18,200 feet/sec, 5,550 m/s: The Rocket Company. http://books.google.com/books?id=ku3sBbICJGwC&pg=PA174&lpg=PA174&dq=%22direct+descent%22+Moon+delta-V&source=bl&ots=V0ShEuXLAv&sig=QIpkcV9Gtu-rYMOYJpLOmWwsy54&hl=en#v=onepage&q=%22direct%20descent%22%20Moon%20delta-V&f=false Another approach would be to find the Hohmann transfer burn to take it from LEO to the distance of the Moon's orbit but don't add on the burn to circularize the orbit. Then add on the value of the Moon's escape velocity. I'm looking at that now. Here's another clue. This NASA report from 1970 gives the delta-V for direct descent but it gives it dependent on the specific orbital energy, called the vis viva energy, of the craft when it begins the descent burn: SITE ACCESSIBILITY AND CHARACTERISTIC VELOCITY REQUIREMENTS FOR DIRECT-DESCENT LUNAR LANDINGS. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19700023906_1970023906.pdf The problem is I couldn't connect the specific orbital energy it was citing to a delta-V you would apply at LEO to get to that point. How do you get that? Bob Clark

Thanks for the info. Bob Clark

Thanks for those refs. I\'ll give them a read. Bob Clark

Robert Zubrin has proposed lower cost missions using the new Falcon Heavy rocket: MAY 16, 2011 Robert Zubrin\'s Proposes using three Space Falcon Heavy Launches to send two people to Mars by 2016. http://nextbigfuture.com/2011/05/robert-zubrins-proposes-using-three.html MAY 17, 2011 Zubrin provides more explanation of his Space Falcon Heavy Mars Plan. http://nextbigfuture.com/2011/05/zubrin-provides-more-explanation-of-his.html Bob Clark

That\'s a good plan. That notation with the power as a superscript between the 'sin' and the '(x)' does indeed mean raise the sine function to that power. On a calculator you could enter like this: (sin(x))^2. To get an idea of what the answer to your problem is try plugging large numbers on your calculator into: (sin(x))^2/(x^2+1) Bob Clark

Hello, just joined the forum. How do you get the mathematical formulas into your posts? Bob Clark

Hello, newbie here. I have some spacecraft proposals that I want to create simulations for that I discuss here: The Coming SSTO\'s. http://exoscientist.blogspot.com/2012/05/coming-sstos.html How do you use the kerbal program to simulate a space launch? Also does kerbal have accurate trajectory calculators where you can get a good idea about how much payload your rocket can get to orbit? Thank You, Bob Clark