Tropical storm Josephine turned into a hurricane today, forcing space shuttle planners to think about keeping Challenger in orbit an extra day or diverting it from Florida's Kennedy Space Center to California for its planned return to Earth on Saturday.

Sucking up energy from the warm Atlantic east of the Bahamas, Josephine's winds grew from 50 mph to 80-90 mph in less than eight hours. Still 500 miles east-northeast of Miami, Josephine today began crawling north at five mph.

Although weather forecasters were predicting that the storm would remain on a northerly path that would keep it 400 to 500 miles offshore, there was concern that it could move toward Cape Canaveral.

"We're going to try to go in there, but my guess is it will be a decision we'll make at the last minute like we always do when we're trying to land at the Cape," Flight Director Cleon Lacefield said at Houston's Johnson Space Center.

Bad weather already has forced the rerouting of two of three previous attempts to land in Florida. Astronaut Robert L. Crippen was mission commander both times, as he is on this flight.

If Josephine does move in over Cape Canaveral, it should be clear of the Cape by Friday or Saturday. If so, Challenger's crew may be asked to spend an extra day in orbit and land in Florida on Sunday.

One reason shuttle officials want Challenger to land at the Cape is the damage done at liftoff to one of its engine pods. The pod must be fixed quickly in Florida, as Challenger is due to fly again in early December.

"We cannot cannibalize an engine pod from the shuttle Discovery since it is due to fly in November," a source said.

Flight directors also were looking at what caused the Tracking and Data Relay Satellite (TDRS) being used by the shuttle to fail for more than 13 hours Monday.

The initial explanation was that cosmic rays from a sunspot had caused the failure. Today's explanation was that a cosmic mistake by a human may have been responsible.

The full moon may have gotten into the field of view of a sensor on the satellite. When this happens, as it does every month, someone at the White Sands, N.M., facility where the TDRS is controlled is supposed to switch sensors so the satellite does not confuse the moon and Earth.

"It appears the command to switch Earth sensors was not sent," said Robert Sperry, associate chief of networks at the Goddard Space Flight Center in Greenbelt, Md.

This morning the crew held an "international" news conference via radio links to reporters in Houston, Australia and Indonesia. But when the Indonesian reporters tried to join in, all they heard was the ringing of a telephone and a disembodied voice saying: "If you need help, please hang up and dial the operator." The comment brought gales of laughter from Challenger.