Information on the density of the upper atmosphere obtained from observations of the Russian satellites will lead the United States to launch its own satellite higher than was originally planned, the Smithsonian Astrophysical Observatory announced yesterday.

Fred L. Whipple, director of the observatory, said that a joint study of Sputnik by Smithsonian and the U.S. Naval Research Laboratory revealed that the air at an altitude of 140 miles is "five times denser" than previous American rocket studies had shown.

The U.S. will therefore have to launch its satellite about 30 miles higher than originally planned to confront the same atmospheric drag, according to Whipple. The data about the air was obtained through a combination of radio and optical observations.

The Institute also released information regarding the death of Alpha I, the first Sputnik's rocket, which should come to earth over the weekend. Dr. Armand Spitz of the Smithsonian staff stated that the "actual death of Alpha should be a spectacular event, a bright flashing streak visible for hundreds of miles."

Though it is impossible to predict where it will fall, since most of the earth is water and uninhabited land, the fall may not be within human eyesight, Dr. Spitz asserted. He said that the flash would be brilliant at night and possibly so bright that it could be visible in the daytime.