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The Question

(Submitted November 26, 1997)

Could you send me some info on Anti-Matter and on Nuclear Powered Spacecraft Engines?

I've seen these two things on the internet or FOXTEL and would like to know some more about them.

The Answer

Our website contains a lot of information on antimatter. If you enter 'antimatter' into the search feature on our homepage you will get a list of links to all the places the topic is discussed.

There is a book called 'Mirror Matter' by Robert Forward which talks about engineering with antimatter and using it to make rockets. It is currently out of print, but it may be in a local library. Hardcover, 262 pages, Published by John Wiley & Sons, Publication date: May 1, 1988, Dimensions (in inches): 9.50 x 6.65 x .98, ISBN: 0471628123,

NASA does not have plans or designs at present on either nuclear powered rockets or anti-matter engines. Anti-matter is very very very expensive to make (a gram of antiprotons would cost several hundred billions of dollars to make...). And you thought the price of gasoline was bad! It's really not a good choice for fuel right now nor into the easily foreseeable future. Science fiction authors do like it, however. Nuclear engine designs are, however, somewhat more realistic. The real bugaboo is safety: what happens if the rocket fails or explodes. I know of only one particular design for nuclear rockets (although I'm certain many exist) called "Orion" which consists of a very large metal plate lofted to orbit by exploding low yield atomic bombs underneath it. As you can imagine, the "rocket exhaust" for an Orion vehicle would pose some serious environmental hazards...

That said, there are far more interesting things NASA REALLY IS DOING! New rocket designs like aerospike engines, supersonic combustion ramjets (often called "scramjets"), solar/electric propulsion, ion drives... For the scoop on some of these fascinating and REALISTIC ideas, check out the Breakthrough Propulsion Physics Program page at

The truth is even more exciting than fiction!

You also might want to search the WWW for information on new rockets such as the X-33 program.

Jesse Allen, with help from David Palmer and Paul Butterworth
for the Ask an Astrophysicist Team

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