Endeavour Returns After 16 1/2-Day Mission : Space: Astronauts touch down at Edwards Air Force Base, ending the longest flight in shuttle history.

The space shuttle Endeavour and seven astronauts touched down in California’s Mojave Desert on Saturday, ending a 16 1/2-day stargazing mission, the longest flight in shuttle history.

Shuttle commander Stephen Oswald guided Endeavour through clear skies to an Edwards Air Force Base landing at 1:47 p.m., leaving a couple of thundering sonic booms in his wake. The mission ended 16 days and 15 hours after the crew blasted off from Kennedy Space Center in Florida.

The astronauts traveled 6.9 million miles and circled Earth 262 times during NASA’s 68th shuttle flight, Endeavour’s eighth.

The longest previous shuttle flight was 14 days and 18 hours by Columbia last summer.

“Welcome home Endeavour, after a fantastic record-setting mission. It will be a tough one to beat,” Mission Control’s Curtis Brown told the crew after Endeavour rolled to a stop on the runway. “It sure is nice to have you all home.”

“It’s nice to be here,” Oswald replied.

More than 1,000 spectators filled a viewing stand and another 100 VIPs, including crew members’ families, watched the afternoon landing. NASA officials made last-minute arrangements for Administrator Daniel S. Goldin, accompanied by two daughters and a grandson, to witness the landing.

Goldin earlier in the week had been at NASA’s Ames Research Center in Mountain View, Calif.

Goldin greeted Oswald and two other astronauts--Wendy B. Lawrence and William G. Gregory--in the bright sunshine while they still were in their orange flight suits and getting their land legs.

The astronauts were scheduled to fly to Houston today after extended medical evaluations, said NASA spokesman Don Haley.

Stormy weather in Florida thwarted attempts on Friday and Saturday to return the shuttle to its home base. Aside from slight crosswinds, the weather at Edwards was good, with high scattered clouds. Wind kicked up swirling dust from the dry lake bed surrounding the concrete runway.

As the shuttle made its final approach, its twin sonic booms were felt throughout the Los Angeles area.

NASA prefers to land its shuttles at Kennedy because it costs $1 million to ferry them across the country atop a modified jumbo jet. It also adds about a week to the turnaround time shuttles require before they fly again.

Endeavour’s next flight is in July. The craft should begin its piggyback return trip by Thursday, Haley said.

Endeavour was launched March 2 with a $200-million observatory in the cargo bay. The astronauts, including four astrophysicists, worked 24 hours a day in two shifts to point three ultraviolet telescopes toward the heavens.