Next time you go to the swimming pool (deep end), jump into the middle of the
pool. Does your body sink or float to the top or stay somewhere in the middle? If you
sink, you are negatively buoyant. If you float, you are positively buoyant. And if you
are somewhere in the middle, you are neutrally buoyant.
So what does this have to do with the Hubble Space Telescope?
Here's my story.
I was underwater the first time that I came into contact with the Hubble Space
Telescope in the early 90's. As a NASA employee in Huntsville, Alabama, I was currently
working as a Space Station Freedom Project Office employee for Marshall Space Flight
Center (MSFC). However, all certified divers at MSFC NASA could register at the Neutral
Buoyancy Tank to do volunteer work in the Tank. All of these volunteers underwent a
rigorous underwater test in order to enter the MSFC Tank that involved donning and
doffing scuba diving equipment at the bottom of a pool that contained 1.32 million
gallons of clear water as well as maintaining an up-to-date certification in first-aid
and cardiopulmonary resuscitation and passing a rigorous physical examination.
On that particular day, I was assigned to take pictures of the HST Goddard Space
Flight Center simulation using an underwater movie camera (position usually denoted as
"the swim camera"). After the test, the video could be used to review the happenings of
the day. Procedures, that would later be followed by the astronauts in space, could be
corrected and equipment redesigned in order to enhance extravehicular activity (EVA).
During the test, engineers, technicians, and other personnel monitored subjects from a
control room which contained several consoles with small monitors and headsets connected
to the communications network. These facilities allowed the test director, test conductor,
safety, and other personnel to view the test and give instructions to the suited subjects
and divers, observer, safety, utility, and photography.
Thus water in the tank was used as the medium for neutral buoyancy to simulate
weight-lessness encountered in space. Underwater, the HST equipment that was tested was
actually a structural mockup, built for tank environment and specifications. The suited
subjects (participants wearing special underwater pressurized space suits that were
neutrally buoyant) were able to perform critical EVA functions in preparation for the
First Servicing Mission by using this mockup.
Remember the saying, "practice makes perfect". NASA Goddard Space Flight Center (in
Greenbelt, Maryland where I now currently work in Operations preparing for the Second
Servicing Mission), was using the neutral buoyancy tests as a tool to prepare for the
upcoming First Servicing mission by having subjects practice in the simulated weightless
environment. Two weeks of on-orbit servicing proved to be a brief interruption to
scientific operations compared with having to return the HST to Earth which would have
posed significantly greater risk of contamination or damage to the Telescope's delicate
components. As a result, unmatched space data and pictures have resulted in increasing
our knowledge of the Universe.
So, next time you go swimming (and you are neutrally buoyant as defined in the first
paragraph), remember reading this journal and pretend that you are an Astronaut in Space
getting ready to perform an EVA. Pick a task, preferably a short one since you'll be
holding your breath, that would show you how different it is working in a weightless
environment. Remember, you will be allowed to flip upside down while performing this task.
Maybe attach small floats to a very heavy object that you would not be able to easily
lift on the ground, like a watermelon, and practice moving it from one place to the next.
Who knows, maybe you'll be performing an EVA in space one day!