material for Flight Day 5 -
SOLAR ARRAY pt 2
Goddard Space Flight Center
The Hubble Space Telescope Project
Hubble Status Report
| Mar. 5, 2002 - 9:02 am EST
The just-completed second spacewalk, or EVA, by the STS-109
astronauts was a tremendous success. Changing out the port
wing of the second generation solar array (SA2), astronauts
James H. Newman and Michael J. Massimino completed the replacement
of Hubble's power-generating arrays. SA3's two wings will
deliver 23% more power than the SA2 arrays they replaced.
The other major activity of EVA#2 was the changeout of reaction
wheel assembly #1 (RWA1).
Hubble's scientific productivity has greatly benefited through
the years by the simultaneous operation of all or most of
its science instruments. Operating the instruments in parallel
requires a great deal of electrical power. The previous solar
arrays, SA2, performed at a very high level, but as expected
they had degraded through the years to the point where full-up
parallel observations would not be possible with the post-SM3B
array of instruments and other equipment. The newly installed
SA3 will permit a more complete scientific program because
there will be sufficient power to run all of Hubble's increasingly
productive instruments simultaneously.
Reaction wheels use changes in spin, or angular momentum,
to move the telescope from one target to another. The RWAs
are also part of the pointing control system, which maintains
extremely precise pointing on individual targets during science
exposures. Three RWAs are needed for science observations,
and with today's changeout the telescope has four healthy
units, providing an important measure of redundancy. The changeout
was necessary because the RWA which was replaced had shown
some anomalous behavior in November, and was not considered
reliable on the long term. CLICK
HERE FOR MORE IMAGES...
Space News :: Latest Items
| Mar. 5, 2002 - 7:54 am EST
With the major tasks of their spacewalk successfully completed,
Mike Massimino and Jim Newman got a head start on some servicing
work for the Hubble Space Telescope.
Following the installation of a new solar array and reaction
wheel assembly, Newman and Massimino were given approval to
proceed with a test of latches on the shroud - or door - that
houses two of Hubble's observing instruments, and to install
some additional insulating material on one portion of the
When those tasks are complete, the two spacewalkers will begin
cleaning up the payload bay before climbing back on board
to complete the second spacewalk of this mission.
| Mar. 5, 2002 - 7:04 am EST
Crew memebrs Jim Newman and Mike Massimino sucessfully replaced
the Reaction Wheel Assembly (RWA). An aliveness test confirmed
its proper operation.
Tuesday | Mar. 5, 2002 - 5:02
Spacewalking Columbia astronauts Jim Newman and Mike Massimino
installed a rigid solar array on the Hubble Space Telescope's
port side early Tuesday, the day after a similar array was
attached to the orbiting observatory's other side.
Also during today's spacewalk they will install a replacement
Reaction Wheel Assembly (RWA), one of four such devices that
point Hubble. That task is scheduled to take about one hour.CLICK
HERE FOR MORE IMAGES...
| Mar. 5, 2002 - 2:55 am EST
Spacewalking astronauts Jim Newman and Mike Massimino removed
the Hubble Space Telescope's port solar array early Tuesday.
They will replace it with a smaller, more powerful solar array
like the one installed on Hubble's Starboard on Monday.
material about this mission day