Crossed Signals Silence Link to Shuttle : Science: Mission Control regains contact after eight minutes of confusion. NASA reports no loss in data or danger to Atlantis’ crew.

NASA briefly lost contact with the space shuttle Atlantis and its six astronauts Sunday because of crossed radio signals.

The problem occurred as Atlantis switched from one Tracking and Data Relay Satellite to another, a routine procedure during shuttle flights. Mission Control uses the satellite network to monitor shuttle systems and talk to the crew.

About the same time as the switch, a computer failed at the Tracking and Data Relay Satellite station at White Sands, N.M., and a backup quickly was activated.

Communication with Atlantis was restored after eight minutes, but it was an hour before engineers realized crossed signals were to blame for the loss of contact, not the computer.

Just before the satellite switch, ground controllers had sent a command to change Atlantis’ radio system from one channel to another. The command never got through because the shuttle was changing its position.

As a result, Mission Control was trying to communicate with Atlantis on one channel while the shuttle was tuned in to another. Another radio system automatically kicked in, and communications returned.

Neither Atlantis nor its crew was in any danger, and no science data was lost, said Mission Control.

A German satellite loaded with infrared and ultraviolet telescopes trailed the shuttle in orbit by less than 60 miles. The astronauts released the satellite Friday so it could measure ozone and atmospheric gases without interference from the shuttle. They’ll pick it up Saturday for the trip home.

Six of the seven atmospheric and solar-energy monitors flying on Atlantis continued to work well. The seventh--a German ozone monitor--remained broken.