Jeff Wright suggests that the Ares
1 has an advantage over the Evolved Expendable Launch Vehicles (EELVs) because it is nonpolluting
[Letters, March 17, page 18]
. This is hardly the case. The Ares uses a solid-fuel booster derived from the space shuttle solid-rocket booster. The solid-rocket booster
uses a fuel composed primarily of ammonium perchlorate and aluminum
and emits hundreds of tons of hydrochloric acid vapor and aluminum oxide smoke during launch – pollutants far more serious than carbon dioxide. Moreover, the solid-fuel booster arrives fully fueled, in a hazardous condition, requires assembly of multiple segments, and is much heavier than a comparable liquid-fueled stage –
all contributing to launch costs considerably higher than those of the EELVs.


The only U.S. launch vehicle that emits no significant pollutants is the Delta 4
Heavy, which is already operational, has essentially the same payload capability as the Ares 1
, and is unique among all the world’s launch vehicles in that it uses only liquid hydrogen for fuel.


Dan Woodard

Merritt Island, Fla.