Launch!

The instrument finally was launched on its balloon this morning at about 5AM local time.  All the pictures I will show you are taken in the middle of the night.  Hard to believe, considering how light it is.  I have been very busy, and have had no sleep for over 24 hours now.  I am stealing time while the package heads towards float altitude, which takes 3-4 hours.

The process for a launch takes about 9 hours.  First we are hooked up to the crane and many tests run.  Here we are hanging from the crane right outside the hanger in the afternoon, around 2PM.  You can see the solar panels.  The instrument is encased in insulating foam and painted white to try to mitigate the wide difference in temperature in space between facing the Sun and facing empty space.  (This was done long ago.)

We then begin hours of communications tests and instrument liveness tests.  It is important for us to monitor the health of the instrument as it flies around and around, especially during the first few hours to make sure that we have all the adjustable settings correct for the science we want to do.  The instrument is very complicated – I’ll talk about that later in another blog – and all of its components must be checked to make sure they are still working.  The instrument has a variety of communications channels, all of which also must get tested.  First there is a direct radio signal.  This is good while the instrument is visible from the launch site, but it travels a large distance around Antarctica, so there has to be a backup.  There are two, both satellite based.  First, there is TDRSS.  Secondly, the infamous Iridium system.  Both are systems that would also sell you time on a satellite phone, if you wished.  Communications through these systems are very slow and not always reliable. The instrument records all of its data onboard on a flash disk, and sends a fraction through whichever of these systems is available.  We can talk to the instrument during the flight through these systems to further adjust any settings we realize we didn’t get right in the first few hours.  Because communications is so important here there is a building bristling with antennae here.

The launch process is very impressive.  It is run by a subsidiary of NASA called the National Scientific Balloon Facility (NSBF).  These guys are based in Palestine, Texas, but travel all over the world to launch these large scientific balloons.  Once the decision is made to try a launch, everything must move very quickly.  First the payload (our instrument) is driven to the launch site on the crane.  Then the train from the balloon to payload is laid out.  This includes the parachute, already deployed, for when it is time to end the flight and recover the instrument. (Remember, the majority of our data is recorded on board.  No recovery means no science.)  There is a great bustle of activity as guys move around on snowmobiles.  I got my chance to drive one around too.

This process is no different from how a balloon is launched in Palestine, TX or Fort Sumner, NM, except that the equipment here is much heavier.  Note the long white tubes.  These contain helium, which is used to fill the balloon.  The balloon itself is in a wooden crate, and is hauled out on a sledge.

Up until this point the whole thing can be called off at any time if the weather goes bad.  Everything is set up except the balloon.  Once the balloon is out of the box there is no turning back.  NSBF must launch or throw the balloon away.  It is not possible to repack the balloon while in the field.  It is done in the factory under controlled conditions, and is packed very tightly and neatly, so that it rolls out without twists when needed.

The balloon is massive.  When fully inflated at float altitude it can hold a football stadium.  At launch is partially inflated, but as the pressure drops it gets bigger and bigger.  (Note that we had fog this morning.) It is filled through two tubes.  It is very noisy, but takes less than 30 minutes.  The balloon is held down by a spindle which is mounted on a heavy platform.  After filling for awhile, the balloon stands up, reaching about 150 feet into the air.  The spindle rotates upward, out of the way, when the launch occurs.  While it is standing above the instrument it is 1000 feet tall.  This explains why the winds have to be so cooperative, and why it takes so long to find a good launch window.

That’s when the excitement really starts for a few select members of the launch team.  The balloon and instrument are laid out so that the low winds that are present carry the balloon as it rises over the payload.  The winds REALLY must cooperate.  No shear (crosswinds) are allowed, and the speed must be very low (less than 8 mph).  As the balloon rises the crane driver maneuvers the payload to be directly beneath where he thinks the balloon will be when it has finally extended the train all the way.  A person standing on the crane has a wire in his hand connected to a pin that holds the instrument to the crane.  When he judges that the balloon has taken the weight of the instrument he releases the pin (BE CAREFUL! THIS LINK IS A LARGE MOVIE! 144 MB! SEE NOTES BELOW), and the instrument gently floats into the air, up, up, and away.  At least that’s the theory.  The balloon has enough lift to topple the crane over if it pulls sideways.  Look carefully at the picture of the crane and you will see the side pontoons to help prevent this disaster.  (The movie is in avi format, which I use Windows Media to view.  If you have WM associated with avi it will start automatically.  If not, you can save the file to disk using the right click button, then start WM and then open the file.)  Here is another movie to give you an idea of how noisy the filling process can be.  During this whole process I stood around watching, taking pictures, keeping from getting too cold.

Once loose the balloon ascends at 1000 feet per minute.  This is very fast.  It takes about two hours to get to float altitude of 120,000 feet.  Remember that commercial airplanes fly about 36,000 feet at most, so the balloon is not a hazard to navigation except while it is going up and coming down.  After coming back from the runway I stopped in our primitive facilities (other side is MENs). Then I tried to sleep during this time since the instrument was off and it was 6AM for me.  

Once at float altitude we will spend time fooling around with various settings until we are happy with the performance.  And then we will go back to McMurdo to sleep.  More later….