December 21, 2015

On Monday night, people living on the Florida coastline took part in an all-new spectacle: a rocket descending and landing gently. Citizens living there had enjoyed for years the sight of shuttles heading for space.spacex-will-attempt-a-potentially-historic-rocket-landing-like-never-before-this-weekend

“It really felt like it was right on top of us,” Elon Musk, the chief executive of Space Exploration Technologies Corporation of Hawthorne, Calif., or SpaceX for short, said during a telephone news conference afterward.

With the rush of sound from the rocket engines, Mr. Musk, who was at the launch site in Florida, said he initially thought the landing was a failure, ending with an explosion. But then he heard from mission control that the booster was standing, in one piece.

For SpaceX, the 8:29 p.m. liftoff of the Falcon 9 rocket from Cape Canaveral Air Force Station was a threefold success.

First, it marked the company’s return to flight after half a year. In SpaceX’s last launch attempt, a rocket taking supplies to the International Space Station disintegrated. (This time, the rocket was carrying a commercial payload: 11 small data-relay satellites for Orbcomm of Rochelle Park, N.J.)

Second, SpaceX’s upgraded design for its Falcon 9 rocket worked flawlessly. The liquid oxygen was chilled to minus 340 degrees Fahrenheit, about 40 degrees colder than on earlier flights, and the kerosene fuel was cooled to 20 degrees instead of 70 degrees.

Mr. Musk explained last week via Twitter that the lower temperatures improved performance of the rocket engines.

Source : http://www.nytimes.com/2015/12/22/science/spacex-rocket-landing.html?_r=0