March 4, 2002, 12:00pm CST
Dr. Edward Cheng (different Ed)
HST Development Project Scientist
Johnson Space Center
 Another
great day in space last night. If it were not for the fact that
mission preparations take two years to complete, one might be tempted
to think that working in space is a piece of cake!
Last night, we successfully replaced the first of two solar arrays.
There were a few mechanical snags that slowed things down, but everything
went pretty much as expected. The astronauts worked for a total
of 7 hours and 2 minutes (25.306 Ksec), very close to the original
plan. We did discover a small anomaly in the behavior of the electrical
system as the new panel was installed. During this procedure, a
small current was flowing through a path that was not originally
predicted. However, this is now understood and the procedure for
the second panel changed to avoid the situation. The effect does
not present a problem for either the crew or the spacecraft, but
is easily avoided. Dr. Ed Cheung, a contributor to this page, has
been working hard on understanding this effect. Thanks, Ed!
Everything on the Shuttle and on HST is normal, and ready for the
second day of EVA. Tonight, we'll get the second new solar panel
on, and replace a reaction wheel assembly that is used for pointing
the telescope.
The headache metric today reads:
Excedrin: 1
Tylenol: 1 + 3 = 4
Bayer: 0 = 0
Aleve: 1
Advil: 1
March 3, 2002
Dr. Edward Cheung (Jackson & Tull)
HST Principal Engineer
Flight Day 3 Report
 I
am writing this from the Johnson Space Center, where I will be working
for the duration of our servicing mission. We just finished our
first day with Hubble, and everything is going very smoothly.
We work each console position in two shifts, 12 hours each. Because
of the time of launch, the astronauts do their space walks during
our night. This latter 12 hour period is called the 'Orbit Shift'.
The other is called the 'Planning Shift'. I staff my position during
the Planning Shift. It is the role of our shift to plan the next
day's space walks in response to any problems that occurred on the
previous day(s).
In the previous missions, I worked the Planning Shift also, but
at night. Working a mission during the day is much less physical
stress, and is a relief. The guys on the Orbit Shift can stay awake
at night by following the astronauts, and solving problems as they
arise, but it is still a long night.
On the previous day, we caught up to the Hubble Space Telescope,
and grabbed her with the Shuttle Robot Arm. I am still amazed we
can do this delicate game of catch-up with another craft going Mach
25. After we matched orbits, she was then fastened to the Shuttle
using one of the carriers called the FSS.
Seeing HST is like seeing an old friend again that you have not
seen in years. She is very dear to our hearts. Our initial assessment
is that the outer surface looks good, and not damaged too much from
the sun. We then successfully rolled up the two solar arrays. This
roll-up did not occur without problems on the first mission in 1993,
so our team worked on tons of plans in case of any problems. We
covered all kinds of possibilities, even flying additional hardware
to protect against any problems. Happily, all that work went to
waste, as they both rolled up just fine.
Tomorrow morning, the astronauts will replace one of the solar arrays
during their first space walk. As part of the job, they will be
installing a unit called the Diode Box Controller (DBC), a system
I designed. I will document as much as I can on my mission web site.
Then the day after, another pair of astronauts will install the
second solar array, again with another DBC.
Electrical power is a spacecraft most precious resource. Power means
life. Lack of it means destruction and loss of the spacecraft. The
DBC has control over the HSTs power, and as a result has a very
important job. I took this responsibility very seriously during
the design of the DBC. Power handling is a very large part of this
mission, and I will describe more about it as the mission progresses.
More from Ed at: http://www.edcheung.com/job/sm3b/sm3b.htm
Click here for more
pictures of the rendezvous with Hubble...
March 3, 2002
Dr. Edward Cheng (different Ed)
HST Development Project Scientist
Johnson Space Center
 A
great day in space last night, and a boring day on Earth today.
That's great news for everyone!
Last night's accomplishments include a flawless Shuttle docking
with HST, and the successful stow of the old Solar Arrays. This
paves the way for the Solar Array replacements which will start
late tonight, early tomorrow morning.
Everything on the Shuttle and on HST is normal, and ready to support
the servicing mission as planned. There were some concerns about
a Secondary Oxygen Pack on one of the astronaut suits, but this
has been worked out and is not a concern any more.
The team is excited that things have gone so well at this preparatory
stage, and looks forward to the challenging work ahead.
The headache metric today reads:
Excedrin: 0 + 1 = 1
Tylenol: 0 + 1 = 1
Bayer: 0 = 0
Aleve: 1 (miscount from yesterday said 2) = 1
Advil: 0 + 1 = 1
March 2, 2002
Dr. Edward Cheng (different Ed)
HST Development Project Scientist
Johnson Space Center
 After
a spectacular early morning, on-time launch yesterday morning, a
part of the HST Management Team flew from the Kennedy Space Center
in Florida to the Johnson Space Center (JSC) in Houston. The HST
Project, known to the Shuttle world as the "Payload Customer,"
maintains a 24-hour group at JSC for close coordination with the
Shuttle Mission Managers. The main part of the HST Project operates
out of the Goddard Space Flight Center (GSFC) in Greenbelt, MD where
most of the experts reside.
After launch, the Shuttle Team noticed a reduced flow condition
on one of the two freon cooling loops that maintains the temperature
of the shuttle avionics. The concern is that at least one fully
functional loop is normally required for safe return, and having
one degraded loop will reduce the level of redundancy. This situation
is being closely monitored and discussed several times a day.
Here is a situation that illustrates some of the dynamics of a large
organization in a critical operations period. Almost immediately
after this situation was discovered, rumors of terminating the flight
and "coming home" appeared immediately in phone calls
and through the internal communications channels. This proves once
again that bad news spreads faster than the speed of thought! Even
for a mission team that is as highly trained and professional as
the HST Team, this event required some intervention. In large part,
this was because a lot of people were en route travelling to their
mission positions after launch, and were not plugged into the normal
communication channels.
As the team settled into their positions and normal communication
established, it was made clear that we have a situation that needs
to be monitored, but poses no immediate threat to continuing the
Servicing Mission. We will likely be able to make a final assessment
of this in about a day, after the Shuttle Team has looked at all
the data, and has completed some thermal analyses.For now, the HST
Project is proceeding with the nominal mission as planned.
All HST systems appear to be normal as the HST is being prepared
for its fourth rendezvous with a visiting Shuttle. The aperture
door has been closed, and science observations have stopped as HST
Operations makes these preparations.
Since
things are moving along as planned, all of us working the shifts
are getting what we always hope for ... a dull and boring shift.
So far, we are getting our wish.
We have a "Ready Remedies" analgesic dispenser at the
JSC Management Table. It contains 5 types of standard pain killers,
with 15 doses each. I will maintain a count of usage during this
mission as a "headache metric." Here is the current count
of packages used:
Excedrin: 0
Tylenol: 0
Bayer: 0
Aleve: 2
Advil: 0
Mar.
1, 2002
Dr. Edward Cheung (Jackson & Tull)
HST Principal Engineer
Launch Day
 As
you may have heard on the news, the launch was scrubbed on February
28 due to weather. The day before we spent touring the KSC Visitor
Center, and the wind and cold was vicious. The temperature was in
the fourties, and the wind cut right through us. As a result, I
was relieved when the scrub was announced at 3pm, rather than 3am.
I have been to launches that required us to get up very early in
the morning (2 am), only to be scrubbed after we were bussed to
the launch site...
By shear luck, we were assigned to the best visitor launch viewing
site, the 'Banana Creek Viewing Site'. I have never seen a launch
from this location, and it was spectacular. The distance was about
3 miles to the pad, while visitors are usually kept 6 miles away.
Only the press site and the VAB has a slightly better view than
us.
The angle of the sun at 6am allowed us to see the Hubble Space Telescope
as a bright Eastwardly moving star. She passed overhead at Tee equal
zero, and it made her look so close, I could reach out and grab
her myself. Without a break in the count down, the Launch time hit
zero, and the early morning turned into day as a trail of fire like
a bright rooster tail rose over the chilly Florida morning. I could
feel the vibrations on my chest as the sound wave finally hit us.
We could also see the SRBs separating, and they had their own trail
coming down. It was very exciting and tangible to see HST going
by like a star, and the Shuttle shooting off to catch her. It is
a great feeling to know that 'tonight' my hardware is in space once
again.
HST's pass overhead dramatizes why we have a launch window, and
why we have to get up at 2am. In order to stay within the operational
envelope of the Orbiter, we need to launch with precise timing.
Just like a quarterback throws the football at where he thinks the
receiver will be, so do we have to prepare a launch trajectory to
take HSTs speed into account.
I will spend one last day here, then I will head to Johnson Space
Center for my appointed console position. I will write you from
there.
More from Ed at: http://www.edcheung.com/job/sm3b/sm3b.htm
Click here for more pictures
of launch...
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