March 6, 2002
One Hubble Girl's View by Ann Jenkins
Mission Control, Houston
EVA 3 and the Next Morning
 WAITING
TO EXHALE
After a long, nerve-wracking night, we finally got word minutes
ago: Hubble has a heartbeat once again! Last night was the spacewalking
surgery that stopped our baby's heart and kept it stopped for more
than 6 hours. But now, with the aliveness and functional tests complete,
we're happy to report that our telescope's new electric heart is
once more beating strong and steady.
The aliveness test came at the end of an arduous spacewalk, but
before the astronauts returned to the Shuttle. They stood by (well,
floated) while controllers sent power into Hubble. And Hubble responded
by coming back to life!
I really expected to hear cheers at that news. I figured that the
the sense of happiness and relief would be uncontainable. But up
here in the Payload Control Center at Mission Control, the mood
was far more serious. My co-workers noted the moment, but--ever
the engineers--they did it with extreme caution. I think they were
waiting for the more thorough functional test to be performed.
Well, hours later, the test is finally finished--and Hubble's new
heart is alive and healthy! But the group that worked through the
night is now sleeping so they will be fresh for tonight's spacewalk.
The day shift is in, but they're off on other tasks to prepare for
this evening. Anyway, they weren't here through the rollercoaster
ride that was last night. When the word finally came, of course
they cheered. But I wish all those folks who had endured the long
and agonizing night could have been here to cheer with us. I bet
the astronauts would have heard us in orbit!
March
6, 2002, 12:00pm CST
Dr. Edward Cheng (different Ed)
HST Development Project Scientist
Johnson Space Center
 What
a relief! The Power Control Unit (PCU) changeout last night went
about as flawlessly as can be expected, and HST is waking up after
taking a 4 hour nap. (Well deserved after 12 years of continuous
work advancing the frontiers of knowledge!) The PCU functional tests
have been successfully completed, and most of the subsystems will
be back on-line after a few more hours of commanding and checkout.
Needless to say, the team has worked exceptionally hard on this
aspect of the mission, and this is a great achievement. HST now
has a new and fully functional power system to take it to the end
of its mission. The net result is that we have about 30% more power
on the spacecraft now, compared to before SM3B.
How does this stack up? We now have about 3 kilowatts (orbit average)
available from the solar arrays. (Previously, this number was more
like 2.3 KW, so we gained about 0.7 KW.) A quiescent HST that is
doing nothing consumes about 1.9 KW. So in terms of available power
to do science, we went from something like 0.4 KW to 1 KW, over
a factor of 2! This increase in power capability is one of the things
that makes it possible to put up new generation instruments like
the Advanced Camera for Surveys (ACS), the NICMOS Cooling System
(NCS), and two more new instruments for SM4.
Last night's activities were not without some high drama though.
Before the astronauts started decompression of the airlock, Grunsfeld's
backpack for his spacesuit started leaking water. This was just
at the point where we had stopped "warming up" the HST
in preparation for turning its power off. Controllers at GSFC immediately
resumed the heating, and postponed the power off sequences until
the issue was resolved. The leak was isolated to a valve which should
not have opened until the astronauts were in vacuum. The conjecture
is that a power glitch in the umbilical that powers the suit in
the airlock caused this problem. As a result, the astronauts will
be using battery power instead of the umbilical for future EVAs.
The crew did a superb job of switching over to another suit, resulting
in a EVA start delay of only around 2 hours.
The astronauts worked for a total of 6 hours and 48 minutes (24.485
Ksec). Everything on the Shuttle and on HST is normal, and ready
for the fourth day of EVA. We'll be getting to the first of two
"science oriented" EVA days tomorrow, with the installation
of the ACS instrument.
The headache metric today reads:
Excedrin: 1 + 4 = 5
Tylenol: 4 + 1 = 5
Bayer: 0
Aleve: 2 + 1 = 3
Advil: 3 + 4 = 7
Clearly, we had an exciting day.
March
5, 2002
One Hubble Girl's View by Ann Jenkins
Mission Control, Houston
Flight Day 5 and the next EVA
 As
of this morning, Hubble now sports two beautiful new rigid arrays
and a fresh and healthy reaction wheel. The mission's first two
nights of spacewalks went exceedingly well, with the astronauts
successfully completing all scheduled tasks--and even managing to
squeeze in two extra "get-ahead" tasks. We couldn't be happier!
Now it's time for shift handover, with the mission's two teams huddled
around consoles discussing the flight day's events. We split the
day into two 13-hour shifts to allow for continuity and smooth transfer
of information. I sit here in the Payload Control Center and watch
my colleagues with a reverence I generally reserve for childhood
heros. These are just ordinary people. But I've watched them prepare
for this mission for years, working long days and nights, sacrificing
so much time they could have spent in other, more enjoyable ways.
All to get to this point, and to cheer like a crowd at a football
game when they hear the good news from the aliveness tests. I love
to just sit like a fly on a wall and watch.
I hope I hear those cheers tonight, because this is the night we've
all been dreading. This is the night we turn off Hubble--our beloved
Hubble--for the first time ever. What we're doing tonight has been
compared to a heart-lung transplant. It's the changeout of the Power
Control Unit, which pumps electricity throughout the telescope.
This electricity powers all of Hubble's instruments and systems
and is the very lifeblood of the telescope. And however irrational
our anxiety is, we worry about what will happen when we try to turn
Hubble back on.
We have a great astronaut crew--clearly the best of the best at
NASA. We know them and trust them implicitly. But we still worry
the way a parent would worry about a child going in for surgery.
A surgery that will momentarily stop our baby's heart. We're already
holding our breath...and we won't exhale till this task is through
and Hubble's electricity is flowing again.
I'm off to TRY to get some sleep. Stay tuned.
March 5, 2002
Dr.
Edward Cheung (Jackson & Tull)
HST Principal Engineer
Flight Day 5 Report
 The
mission has been progressing amazingly well, better than the previous
one in 1999. We just finished our second space walk (EVA) day, and
we now have two new powerful Solar Arrays on the Telescope. The
Arrays' power is controlled by a pair of Diode Box Controllers,
which I have spent the past two years building and testing. Their
passing their functional test is a great feeling! HST now has plenty
of power for the future. We also have a new Reaction Wheel, which
is used to orient HST in space. I did not work on this latter piece
of hardware.
Here at Johnson I work the console position named 'Systems Manager'.
Three other colleagues and I staff this position. Our job here at
the Systems Manager console is to monitor the Shuttle to HST combination.
If there is a problem that involves the Shuttle to HST interface,
one of us will be assigned to work it. Of course, since we are still
HST engineers, if there is a problem we can assist with on the HST
side, we will jump in.
Such it was yesterday when we saw a spike in current from one of
the HST screens. I just came on shift then, and everyone was very
high state of activity due to this unexpected current. The astronaut
was just handling the Solar Array connectors, and we thought the
current had something to do with what he did. Since there was nothing
else happening, both Goddard and us started to work on this problem.
It took a few hours, with telecons back to Goddard, but I finally
figured out what the problem was, and the whole project was patting
me on the back for that. Fortunately, this has been the only significant
electrical anomaly. We had to solve this because the same circumstance
would occur today when we install the second solar array.
I do not think that I am exaggerating when I say that tomorrow will
be the most difficult space walk in history. We will be changing
out the heart of HST's power system, which will require powering
down all of the telescope. This will involve removing a box that
was not meant for in space servicing, and that has many connectors.
This has not been done before, but we are confident all will go
well. It will be a great thrill when it is completed.
Since the telescope will be powered down for so many hours, we are
currently performing what is called the 'preheat'. This is where
we basically light up the Telescope like a Christmas tree, turning
on every load we can to get everything good and warm. This allows
us to remain unpowered for the longest amount of time so that the
equipment does not cool below their allowable temperatures. Since
we monitor the Shuttle to HST interface, we monitor the power usage,
which is off the chart right now. To give you some real numbers,
HST is drawing 2.5 kWatts from Shuttle at the moment.
More from Ed at: http://www.edcheung.com/job/sm3b/sm3b.htm
Ed's Web page on the Diode Boxes: http://www.edcheung.com/job/dbc/dbc1.htm
Click here for more pictures
of Flight Day 5...
March
5, 2002
One Hubble Girl's View
by Ann Jenkins
Mission Control, Houston
Some Photos of Our Team
At Mission Control in Houston, we work at consoles 24 hours a day
throughout the mission. Most of us are split into two 13-hour teams
that overlap for hand-off. The long days and nights require intense
concentration, but we try to find time to enjoy the moment. The
work is hard, we miss home, but we all know that being a part of
this mission is the opportunity of a lifetime.
March 5, 2002, 12:00pm CST
Dr. Edward Cheng (different Ed)
HST Development Project Scientist
Johnson Space Center
 Last
night, we successfully replaced the second of the two solar arrays.
We also replaced a Reaction Wheel Assembly. All the replaced hardware
has passed functional tests and are working fine. There was some
time left over, so the astronauts replaced some torn insulation,
and repaired a door hinge on the aft shroud. These "get-ahead"
tasks are optional things to do to save time for subsequent EVA
days or servicing missions.
The astronauts worked for a total of 7 hours and 17 minutes (26.204
Ksec).
Everything on the Shuttle and on HST is normal, and ready for the
third day of EVA. Tonight, we'll change the Power Control Unit (PCU).
This will be a stressful time, since it would be the first time
that power is entirely turned off on the spacecraft since it was
launched. (Individual systems are power cycled as needed, including
during previous servicing missions.) We don't anticipate a problem,
but it's not something one does lightly.
Life continues at a predictable pace in the control center. No great
excitement ... just the way we like it. However, it is tiring all
the same, with adrenalin running high for 12 hour shifts. We're
getting our share of stomach aches from too many Krispy Kreme doughnuts
and meatball sandwiches from Frenchies.
The headache metric today reads:
Excedrin: 1
Tylenol: 4
Bayer: 0
Aleve: 1 + 1 = 2
Advil: 1 + 2 = 3
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