What have we learned from Hubble about building telescopes?

FYI...

In reference to my question, I would say that designers need to build
any scope for future repair and updating.

Your thoughts?

TMT


Astronauts making one last house call to Hubble
By MARCIA DUNN, AP Aerospace Writer Marcia Dunn, Ap Aerospace Writer
Thu May 7, 5:37 pm ET

CAPE CANAVERAL, Fla. – The Hubble Space Telescope is about to get one
last house call. And never before have the risks been higher.

On Monday, astronauts will rocket away to the most famous telescope of
modern times. They'll be taking up new scientific instruments,
replacement parts for broken cameras and fresh batteries that should
keep Hubble running for five to 10 years.

This cosmic-scale grand finale — stalled seven months by a telescope
breakdown — will be NASA's most daring overhaul yet of the 19-year-old
orbiting observatory, a captivating, twinkling jewel in the sky
representing $10 billion of investment.

Never before have spacewalking astronauts attempted to fix dead
science instruments on the Hubble, equipment that was never meant to
be handled in orbit. Before they've just swapped out the whole thing
at the telescope, which started out life shockingly nearsighted.

In all, five spacewalks will be performed in as many days by two
repair teams. Two of the repairmen have visited Hubble before and,
because of that, were chosen for this extraordinarily difficult job,
on a par with operating-room surgery.

"Hubble needs a hug," said the chief repairman, John Grunsfeld, who
will be making his third trip to the telescope.

Space shuttle Atlantis and its crew of seven will face increased
danger from space junk because of Hubble's extremely high and littered
orbit 350 miles up. They will need someone to come and get them — fast
— if their ship sustains serious Columbia-type damage during launch or
later in flight. They will not have the luxury of camping out at the
international space station while awaiting rescue. The space station
will be in another orbit and impossible to reach.

The mission, once canceled because it was considered too perilous, has
an unprecedented safety net: another space shuttle on the launch pad.
There is no guarantee, though, that NASA could pull off a rescue in
time to save the Hubble crew. It would take three to seven days, at
least, to launch a second shuttle.

All seven astronauts agree Hubble is worth risking their lives for.

"I'm only going to do that if I think it's for something really
important, and I think Hubble is really important," said Grunsfeld, an
astronaut-astrophysicist. Hubble is "worth bringing up to date and
extending its vision even farther."

"It's showing us the way" to distant galaxies and, indeed, the actual
edge of the universe, said the mission's commander, Scott Altman. "The
next step is for us to try and go there."

Altman and his crew were just two weeks away from liftoff last fall
when Hubble broke down and stopped sending pictures. NASA got the
telescope working again with a backup channel on the failed command
and data-handling unit, but the shuttle flight took a seven-month hit
as engineers scrambled to get an old spare unit ready for launch.

The final cost for the entire mission, including all the new tools and
parts, is just over $1 billion.

No telescope ever has received as much hoo-ha or been on such a seesaw
as Hubble, which has circled Earth more than 100,000 times and logged
nearly 3 billion miles.

Launched aboard the space shuttle in 1990, Hubble went "from the top
of Mount Everest to the bottom of the Dead Sea" in two months flat,
observed NASA's science chief, Ed Weiler. The orbiting telescope had
blurred vision; its primary mirror had been improperly ground.

Astronauts fixed everything in 1993 by installing corrective lenses
and returned three more times — in 1997, 1999 and 2002 — to install
better cameras and make other improvements.

In the meantime, Hubble was churning out breathtaking vistas of the
cosmos, including the celebrated image of Eagle Nebula, a star-forming
region 6,500 light years away. The picture is often referred to as
"Pillars of Creation."

Hubble has shed light on the age of the universe (13.7 billion years)
and shown that the universe may be expanding quicker than ever, and
proved the existence of supermassive black holes, among other things.
The telescope has peered back in time to within 800 million years of
the first moments of the universe. The new instruments going up will
take astronomers to within 500 million to 600 million years of
creation.

Ground-based telescopes might see better than Hubble "over a very,
very tiny field of view," Weiler said. "But you don't see Eagle
Nebulas on the cover of Time magazine taken from the ground. You see
them from Hubble. Hubble still has a unique niche."

The 2003 Columbia disaster put the fifth and final Hubble servicing
mission that had been scheduled for 2004 on indefinite hold and, one
year later, completely knocked it off the shuttle lineup.

With the public outraged over the abandonment of Hubble, NASA
considered the idea of sending up a robot to replace the batteries and
gyroscopes, plug in the latest wide-field camera, and perform some
other jobs. But the robot plan never jelled, and the NASA
administrator at the time, Michael Griffin, nixed it. Instead, Griffin
approved one last Hubble tuneup by astronauts. He left NASA in January
with the change in the White House.

Grunsfeld disagreed about the robot mission.

"I have absolutely no doubt it would have worked," Grunsfeld told The
Associated Press. "I do think that we got a little too greedy and
tried to propose that (a Hubble robot mission) would do a lot more
than it really could."

Grunsfeld is quick to note that no robot could have tackled some
chores they'll undertake — installing the new cosmic origins
spectrograph for detecting faint light from faraway quasars and
repairing two failed science instruments.

The spacewalkers will have to undo 117 fasteners to get to a bad
electronics board inside an old imaging spectrograph, and deal with a
hard-to-get-around corner to replace burned-out power supply cards in
an advanced camera for surveys.

"It's right at the edge of what I think people can do, period,"
Grunsfeld said of the repairs.

In addition to all that, the astronauts will put in a new fine
guidance sensor, part of Hubble's pointing system, add some steel skin
to the telescope's blistered exterior. And they will hook up an
improved capture ring so a future robot-guided craft can latch onto
the Hubble and steer the observatory into a Pacific grave sometime in
the early 2020s.

"I think of Hubble as a roller coaster," Weiler said late last month,
referring to all its ups and downs. But the bottom line is, "Everybody
loves Hubble now."

It's even won over the Twittering crowd. Astronaut Michael Massimino
has been filing training updates via Twitter for the past month; he
hopes to post from orbit, but is uncertain whether he'll have time.

Before tragedy struck with Columbia, Weiler envisioned a space shuttle
bringing Hubble back to Earth and the telescope — "the great American
comeback story" — being displayed at the Smithsonian Institution's
National Air and Space Museum.

He imagined "little school kids going up to this huge four-story
telescope and being able to say, 'That's what filled your textbook
with pictures and traveled billions of miles in orbit.' "

Instead, the world will eventually watch as Hubble plunges from the
sky.

Grunsfeld — who will have spent more time working on Hubble in space
than any other human — said he will have no remorse when it comes time
to leave the telescope near the end of the 11-day shuttle mission.

"The increase in Hubble's capability and the life extension is going
to be so phenomenal that I'm just going to be thrilled to see it as it
recedes onto the horizon as just another bright star," he said.

He's already planning a huge party for when Hubble plummets out of the
sky in another decade or so, on a cruise ship somewhere in the
Pacific.

___

On the Net:

NASA: http://tinyurl.com/d3rqj7

Space Telescope Science Institute: http://www.stsci.edu/hst/
.

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