Astronauts in the space shuttle Discovery took time out to marvel at the swirling Hurricane Elena today as they launched the last of three satellites and prepared for the main task of their eight-day flight, a dramatic satellite rescue on Saturday and Sunday.

Commander Joe H. Engle, who took vivid photographs of the huge storm, a dense white circular mass stretching across almost half of the Gulf of Mexico, noted a second storm in the western part of the Gulf and said:

". . . If those several lows ever get together, it's going to be a real whoomer." Engle is from Kansas, where a whoomer is a bad tornado.

Among the contingencies the space agency must face is the possibility that the storm will strike the Houston area and knock out communications with the Johnson Space Center. A NASA spokesman said operations could quickly be switched to the Goddard Space Flight Center in Maryland.

The drum-shaped satellite launched today is almost identical to the Leasat satellite the crew will try to salvage this weekend with two days of spacewalks totaling 9 1/2 hours. Two other satellites were deployed Tuesday, the first day of the mission.

"It's hard to believe somebody's going to be hanging onto one of those things in a few days," astronaut Robert C. Springer said from the Mission Control Center in Houston. Replied Engle: "It looks even bigger close up."

The crew has been told it will have to make consecutive spacewalks Saturday and Sunday to salvage the Navy communications satellite that has been lifeless in orbit since April.

"The work we've done here is showing that the timeline will take somewhere on the order of 9 1/2 hours," flight director Jay Greene said at the Johnson Space Center. "That is the best estimate we can get from using the tools we have on the ground and that implies breaking off the first spacewalk at some logical point and proceeding on to a second walk."

The decision to go for two spacewalks means the shuttle's 20th mission will last eight days instead of seven and land Tuesday at California's Edwards Air Force Base in the dark instead of in daylight.

The crew must take two spacewalks because the shuttle's mechanical arm has lost the use of one of the motors that drives its elbow joint. This means the entire arm -- shoulder, elbow and wrist -- must be worked from inside the shuttle cockpit with backup motors.

"The backup drive motors are not plugged into a computer the way the main motors are," Greene said. "This forces the arm operator into a joint-by-joint operation to get the end of the arm to go where he wants it to go, an extremely time-consuming thing that adds as much as 75 percent more time to working the arm."

The arm will be worked by astronaut John M. Lounge to hold astronaut James D. van Hoften while he wrestles with the dead satellite and will also be used to reposition the satellite so van Hoften and astronaut William F. Fisher can work on it in the cargo bay.