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NASA Looking At Nuclear Thermal Rockets To Explore the Solar System
MarkWhittington writes: Officially, NASA has been charged with sending astronauts to Mars sometime in the 2030s. Toward that end, according to a story in Universe Today, space agency engineers at the Marshall Space Flight Center are looking at an old concept for interplanetary travel, nuclear thermal engines. "...according to the report (cached), an NTP rocket could generate 200 kWt of power using a single kilogram of uranium for a period of 13 years – which works out of to a fuel efficiency rating of about 45 grams per 1000 MW-hr. In addition, a nuclear-powered engine could also provide superior thrust relative to the amount of propellant used." However, some doubts have been expressed whether NASA will be granted the budget to develop such engines.
ancient discredited NERVA/ROVER program which began in 1956 and dragged on to a miserable failed end in 1973
You mean the discredited program that produced working engines and test-fired them on vacuum stands, proving they are practical and work? You might also note another program that was terminated in 1972: Apollo. Oh my, what an abominable failure that one was...
the fact that any rocket has to carry and throw away a vast load of reaction mass
And how else would you propose to move in space? Mr Newton might have something to say here.
But the actual raw energy needed to lift 118 tonnes to 200 km is...
If you think the difficulty in achieving orbit is just lifting something sufficiently high up, you're more dense than I thought... Here's an idea, first learn about something, then start lecturing about it.
No other mode of transportation has to carry its own reaction mass and throw it away. Not bicycles, cars, trains, ships, submarines, or airplanes.
Please note that all of the above modes of transportation have one thing in common: they only work on the Earth. Or when was the last time you last saw a car drive through outer space?
> maximum final Delta V from source of circa 58,000 ft/sec
Einstein would like to have a word with you. That word is "relative". Suppose there is a planet traveling away from the earth at at 50,000 ft/sec. An alien on that planet can fire a rocket, which can travel away from that planet at 50,000 ft/s, meaning 100,000 ft/s relative to earth. As it catches up to another planet, it might photograph some other aliens launching their own rocket at 50,000 ft/s, which is 150,000 ft/s relative to earth.
In fact, the SAME rocket could from earth to the first planet, then be launched from that planet, then stop at the next planet and be launched at 50,000.
Come to think of it, stopping at each planet doesn't change anything. It's ALWAYS standing still relative to something, and can launch away from that something to 50,000 ft/s. The gas leaves nozzle at 58,000 RELATIVE TO THE COMBUSTION CHAMBER. In other words, it can always go 58,000 faster, as long as it can fire it's engine. 58,000 is the limit for a BALLISTIC projectile, one that is fired from a gun and doesn't carry a working engine with which to keep accelerating. The limit is 58,000 RELATIVE TO the chamber in which the gas is burned. By carrying the combustion chamber within the craft, it can accelerate until it approaches C.