| Richard L. Garwin Philip D. Reed Senior Fellow for Science and Technology Council on Foreign Relations, 58 East 68th Street New York, NY 10021 (212) 434-9663; FAX: (914) 945-4419 INTERNET: rgarwin at cfr.org September 26, 2003 (Via Email to overbye at nytimes.com) Mr. Dennis Overbye Editor The New York Times 229 West 43rd Street New York, NY 10036 Dear Dennis Overbye, Re "An Elevator to Space" (September 23) proposing to build two carbon-fiber strands to beyond geosynchronous altitude, there is nothing impossible about this. But its utility is minimal. First, climbing such a strand to the altitude of the most numerous low-Earth orbit satellites (LEO) at an altitude of 300 km or so would not help to put a mass into orbit. It would need to gain a speed of almost eight kilometers per second. Climbing to 300 km at zero speed is best done with a small rocket; but in either case, achieving orbital speed is the major task. Furthermore, we have perfectly good and efficient means of putting satellites into orbit--even into geostationary orbit. My 1988 piece "Space Technology: Myth and Promise" http://fas.org/rlg/myths-of-space.htm notes that for satellite launch to LEO the fraction of the mass put into orbit is only a few percent of the launch mass, but more than 62% of the total energy in the rocket fuel is present in the kinetic energy of the payload. It would be very hard to do nearly so well as this with the conversion of any kind of energy into laser power and the reconversion of that into motive power for climbing the space elevator. What we need is competition in putting small masses into orbit, and that can be achieved far more cheaply than to make the major investment for a space elevator which is, in any case, of very limited utility and will not reduce the cost of launch to orbit. Sincerely yours, Richard L. Garwin Philip D. Reed Senior Fellow for Science and Technology Council on Foreign Relations, New York RLGF:jah:3269ENYT:092603ENYT |