Amid last-minute worries about whether strong high-altitude winds would abate in time for launch, NASA crews bustled through final preparations to start the new space shuttle Challenger on its maiden orbital flight.
After almost three months of costly technical delays, Astronauts Paul J. Weitz, Karol J. Bobko, Storey Musgrave and Donald H. Peterson are due to lift off from the Kennedy Space Center at 1:30 p.m. EST Monday. Later that night, they plan to deploy in orbit a $300 million communications satellite described as the most complex ever built.
The next four days of their five days in space are to be spent performing a space walk and testing the space-worthiness of the second U.S. spaceliner to rocket into orbit.
"To us, this is not the sixth launch of the space shuttle, it's the first launch of Challenger," Launch Operations Director Alfred D. O'Hara said this afternoon at a news conference. "We're very anxious to have Challenger join Columbia in our space fleet."
Columbia, the first shuttle, made five trips into space and is being refitted while Challenger makes the next three shuttle flights.
Flight directors are also anxious to have the astronauts deploy the 5,000-pound Tracking Data and Relay Satellite (TDRS), first of three identical satellites that the United States will use for the next 20 years to provide global communications coverage with all its satellites in Earth orbit.
Not only will the trio of satellites increase coverage between the United States and orbit to 85 percent of the globe from 20 percent, it also will allow around-the-clock communication with sophisticated satellites of the 1980s, whose rate of information return from orbit is 10 to 20 times that of satellites of the 1960s and 1970s.
Without this satellite network to relay their information at high speed back to Earth, the orbiting Landsat satellite, the experimental Spacelab station due to fly on the ninth shuttle flight later this year, and the $1 billion space telescope due to fly in 1985 or 1986 would all be useless.
"There would be no other way to get the kind of coverage we need for the next two decades," Robert O. Aller, director of the TDRS program for NASA, said in an interview. "To match this coverage on the ground would require an expansion of our ground-based network that would cost billions of dollars."
Getting the satellite network into orbit also will allow the United States to close several ground stations around the world.
The total cost of the three new satellites and a huge new ground station at White Sands, N.M., to collect information relayed by the satellites and to operate them for the next 10 years is estimated at $3 billion, but the space agency expects to save money overall. It will also be able to communicate almost continuously with all of the orbiting satellites and with all future shuttle flights, a luxury it does not now enjoy.
By mid-afternoon today, meteorologists were forecasting near-perfect weather conditions for launch time. Skies were cloudless, winds had decreased dramatically and the jet stream that hovered over Cape Canaveral earlier in the week and raised upper-altitude winds to 150 mph had begun moving north.
At midnight, however, the winds were still too high, and NASA officials said the final decision on whether to launch could be delayed until midday.
For all to go well, the astronauts must lift off on time or no later than 2 p.m. The "launch window" for Challenger's first flight is only 30 minutes, dictated by orbital mechanics that require Challenger to be in a precise place above the Earth at 11:30 p.m. Monday night so the astronauts can deploy the satellite from the shuttle's cargo bay.
Just after midnight Monday, a rocket motor is to fire and send the satellite on its way to a permanent perch in orbit 22,400 miles above Earth, where it will hover above the equator just north of the tip of Brazil.