Click on the image to hear Expedition Four Flight Engineer
Carl E. Walz's greeting (366 Kb).
Spacewalking, ISS Style
Astronaut Carl Walz:
In light of
the launch of STS-110, and hot on the heels of the highly successful
STS-109 Hubble repair flight, I thought I would pass on a few observations
of our ISS experience with our U.S. spacewalk hardware.
On 20 February,
Dan Bursch and I donned the U.S. spacesuit, the EMU, and did a five-hour,
47-minute spacewalk. Yury Onufrienko, our commander, suited us up
and then provided camera views while we were outside the vehicle.
This event marked the first U.S. spacewalk since the Skylab program
to be performed without the Space Shuttle present. Since it was
a unique event, it was designated U.S. EVA Number 1. Of course,
we have to date seven ISS spacewalks using the Russian space-suit,
the Orlan without the Shuttle present. Spacewalk is somewhat of
a misnomer, as the work is very demanding technically and physically.
The suit resists almost all movements, so you get a pretty good
workout. The EVA had two major purposes. The first was to verify
that all major joint airlock systems were functional and the second
was to perform get-ahead tasks for the 8A crew. In a way, we performed
the first 8A EVA prior to 8A's launch!
last airlock training had been performed about four months before
the EVA, and our last run in the Neutral Buoyancy Lab (NBL) was
also about four months before, and since we had not ever run the
timeline in the NBL, we required some in-flight preparation that
was different than what a Shuttle-based space-walking crew would
require. Some of the items were things planned by our ground team
for us, and we requested a dress rehearsal of all the spacewalk
preparations up to hatch opening.
Flight Engineer Carl Walz prepares inside the Quest airlock
for a 5-hour, 47-minute spacewalk on February 20, 2002.
was developed by our EVA, Robotics, and Crew Systems Operations
Division Expedition 4 team lead, Dina Barclay, and her EVA team,
which included John Raines, Tracy Snow, and Roger Lottridge. They did a superb job of planning not only our EVA timeline, but all
our preparation and in-flight training activities leading up to
the EVA. Our timeline was verified in the NBL by Pat Forrester and
Joe Tanner, both astronauts with EVA experience on the ISS.
preparation included the use of DOUG, a computer program that provides
graphical depictions of the exterior of the Station. DOUG is a product
of the Virtual Reality Laboratory in Building 9. Dave Homan and
his team did a great job providing us with a superb computer tool
for EVA preparation. Using DOUG and our timelines, we were able
to visualize translation paths, and we were also able to see where
the hardware we would be working with was actually located. DOUG
also allowed us to practice "flying" SAFER, our special jet backpack
designed to propel us back to the Station in the event we would
"fall" off and float away. With no Shuttle present, there was no
vehicle available to pick us up if we floated away. We also had
an EMU trainer program to review EMU malfunctions and emergency
procedures prior to the EVA. This of course allowed us to freshen
up our knowledge of the spacesuit as well. Our suit lead, Tracy
Snow, uplinked training scenarios to us so we could better use these
trainers. It was almost like a training session on the ground.
Typically before a Shuttle-based EVA, the EVA crew has a chance
to perform suited runs in the NBL almost every week. Besides great
practice for the spacewalk tasks, the crews also gain physical training
time, since the stiffness of the suit makes every movement difficult.
We of course did not have that luxury here, so we had to use a combination
of workouts on the Resistive Exercise Device on board the Station,
and also arm ergometry performed on the cycle ergometer, the CEVIS,
to maintain our fitness for the EVA tasks.
From an airlock
preparation standpoint, the Space Station environment affords us
the luxury of time to prepare for the EVA's. While Shuttle-based
EVA's rely on highly choreographed timelines to be precisely executed,
we can perform our preparations in a less-rushed manner. Some preparation
jobs are put on our "task list" where we can perform the activities
whenever we wish. EVA tool check-out, crew-lock preparation, mini-workstation
configuration were all done as task list items.
Flight Engineer Dan Bursch moves around the Quest airlock
We also had
the opportunity to look out the windows of Station to view some
of our worksites. The forward facing window of the docking compartment
gave us a great view of the joint airlock, and allowed us to know
exactly where our safety tether reels were located. Those tether
reels are our main means of security while spacewalking, providing
us a constant secure physical connection to the Station.
the dress rehearsal on 15 February, five days prior to the actual
EVA. The rehearsal, very similar to what we did with the Orlan suits
in January, went really well with all elements of the suit-up process
completed and all equipment checked out, well within the time guidelines.
Astronauts Charlie "Scorch" Hobaugh and Cady Coleman were our capcoms
and helped guide us through the practice. It had been almost nine
months since the joint airlock had been used for an EVA, so the
rehearsal gave us a lot of confidence that all airlock systems were
our bodies for the lower pressure in the spacesuit than inside the
Station, we have to do a pre-breathe before depressurization of
the airlock. We do that with a combination of breathing pure oxygen
from an oxygen mask, including 10 minutes of cycle ergometer exercise
on the mask, and then 72 minutes of pure oxygen breathing in the
spacesuit. The program is pretty complicated, but Dan and I were
both able to perform the exercise, get back to the airlock, and
don the spacesuits without problem. Yury was our hose wrangler,
helping collect the unwieldy oxygen hoses that provided our breathing
gas. Yury also helped us don our spacesuits, which are three-piece
units, as opposed to the one-piece Orlan. He also installed our
SAFER's and gently moved us into the crew-lock.
On the 20th,
EVA day, we got up a little earlier than normal, had a nice breakfast,
and then started the preparations. We had all the necessary equipment
staged the night before, so we were able to start our pre-breathe
early. Because we had practiced getting our spacesuits on recently,
we were able to get dressed in the suits even faster than before.
We were able to open the airlock external hatch about 30 minutes
earlier than planned. We exited the airlock at dawn, and started
our work right away. We attached power cables, retrieved tools for
the 8A space-walkers, removed thermal blankets from the Z1 truss,
did fluid connector inspections, and several other tasks that the
ground needed us to do.
inside and manned the cameras. Joe Tanner, the Chief of the Astronaut
Office's EVA Branch and an astronaut with lots of EVA experience,
provided our task guidance as we performed the various activities
outside ISS. During a Shuttle mission, this activity is performed
by the IVA Shuttle crew member who has spent time training time
with the space-walking crew at the NBL. In the ISS case, where fewer
crew members are available, the ground took over and provided the
guidance. We were blessed with excellent communications with the
ground during the EVA, so it seemed like Joe was inside the Space
Station and giving us his guidance.
From left are Expedition Four Flight Engineers Dan Bursch
and Carl Walz.
of the Space Station looked just like new. It was very shiny and
clean. It was very easy to move around the exterior, as there were
lots of handholds along the way. Our long safety tethers were firmly
attached to structure, and if that failed, we had the SAFER jet
backpack to fly us back to the Station. We worked both night and
day (remember we get sunrise 16 times a day), using our helmet lights
to illuminate our paths when necessary.
was not only a big day for us, it was the 40th anniversary of the
flight of John Glenn in Friendship 7, when he became the first American to orbit the Earth. During the spacewalk, Dan and I reflected on
that anniversary, and afterwards got a chance to talk to Senator
Glenn from NASA Headquarters in Washington.
After the EVA
was over, it was time to put all our space-walking gear away. It
was kind of a sad time, similar to when you take down your Christmas
tree and decorations after Christmas. We will pull it all out again
of course when the STS-110 mission comes to visit.
We would like
to thank our EVA team from the EVA, Robotics, and Crew Systems Operations
Division, the Astronaut Office, the EVA Project Office and the Virtual
Reality Lab for their great work for ISS EVA 1. We also used the
experience from our Russian EVA's to make our EVA 1 successful.
We hope future crews will be able to use our experience to make
their EVA's from the crew-lock successful as well.