aperture door

If the aperture door should jam, for example, space-walking astronauts could pry it open.

They were prepared only to lend a hand if the solar panels or the aperture door to the telescope failed to open properly.

Mission officials said that the telescope's aperture door was reopened on the heavens and that all operations appeared to be normal.

It must keep its distance when the aperture door is opened, as a precaution against contamination of the mirror by gases from the shuttle's steering jets.

Ellsworth Air Force Base (aperture door, 1985)

The telescope's aperture door was then reopened (a 33-minute procedure) and then released at 5:26 am EST.

It closed its aperture door to protect its optics and instruments and aligned its solar panels to the Sun to assure adequate power.

"We have aperture door open," announced Pete Patero, the supervisor of the Hubble control room at the Goddard Space Flight Center in Greenbelt, Md.

If the telescope's aperture door should stick, the Discovery is expected to fly back to a rendezvous with the telescope, and two astronauts would go into space to try to force the door fully open.

With only two working gyroscopes, the Hubble automatically went into "safe mode," a dormant condition in which the telescope closed its aperture door to protect its optics and aligned itself to the sun to ensure its solar panels could draw adequate power.

Aperture Door May Need Help The astronauts aboard the space shuttle Discovery, who placed the $1.5 billion telescope in orbit on Wednesday, continued to fly some 45 miles behind it and were ready to lend a hand if necessary in preparing the Hubble for its 15-year mission of cosmic discovery.