Category Archives: Software

NASA - Week 1

This week I began my work at NASA Johnson Space Center (JSC).  My job is to write software regression test protocols for the guidance, navigation, and control software on a lander prototype.  We normally refer to the software as the GN&C package.  It basically tells the flight computer and flight computer software (FCS) what to do as far as maneuvering the vehicle.

The vehicle I'm working on is called Morpheus and will with any luck be the next machine we place on the moon.  It may take some instrument up after a few more years, but only time and funding will tell.  Below is a picture of the lander with me for scale.

I encourage you to also follow the Morpheus blog from NASA (here).  Videos of tests will be posted there, but I'll also repost.  The first few tests the lander was tied down to the ground.  Then it was hung from a tether and allowed to ascend and land on its own.  Some of the tests worked well, but others had problems as is in the video below.  Most of those issues have been solved and we are now just working on some control lag problems.

More tests were planned very soon, but the rocket started a fire in the test field and we can not light the engine again until the investigate has cleared up, hopefully by early July.  Until we do more field tests I'm working in the NSTL (Navigation Systems Testing Laboratory) trying to do regression analysis.  In general fixing a bug in software can break other features.  When the software is flying a very expensive lander with around half a ton of explosive rocket fuel that is a very bad thing.  I'm using spacecraft simulation code to prove that certain changes don't cause issues with the flight and trying to develop software modification protocols that allow rapid updates.

The icing on the cake was really my first day when I happened to hear that Gene Kranz (the flight controller for many years, made famous in the movie 'Apollo 13') was speaking.  I attended his lecture and it was amazing.  He really has the passion that I love seeing in people.  Mr. Kranz was excited for what our generation can do, but concerned that we may currently lack the leadership to do it.  I agree completely with his statement and all of us in the room are striving to learn those vital skills that he talked about.  The Apollo missions would have never left the ground without leadership, teamwork, and persistance.  While we may have many times the computer power of the 1960's I'm worried we have fewer of these important personal qualities.

The iPad: How it is Revolutionizing Field Work

It's not even been one year since the iPad hit the market and it is well on it's way to becoming an essential for many people around the world.  According to CNN, the iPad has the fastest adoption rate of any consumer advice (read the full article here).  I know that the iPad is difficult to put down, after standing in line all afternoon the day of the 3G release I was entertained the entire weekend.

But, what else can you do with the iPad.  We've all seen the movies, games, and flashy organization apps in the adds, but what about more difficult work?  The productivity category was initially slow to start, but now is full of options.

The numbers/pages/keynote set is $30 ($10 each) and has saved me several times.  When I needed to make a promotion slide last minute at a conference keynote came to my rescue.  I simply took images I needed from various emails and online, added some text, and in 10 minutes had a decent looking slide to submit.  Numbers has allowed me to use some handy computational workbooks in the field to make very simple models of data that is coming in.  Last, pages is very handy for quick edits on the road, or when out somewhere on campus.  There are a few glitches, but they have continually be improving, especially in the area of importing Microsoft Office documents.  So far, no track changes exists, but hopefully that will be coming soon.

For quick remote server administration I use iSSH.  This is really a fantastic app with the exception that the arrow keys/command keys on the bluetooth keyboard don't work forcing you to use onscreen keys.  This is the only limitation that prevents me from doing some full scale programming while connected to another machine back at home.

It's always important to know the weather while in the field and I use a combination of Storm Spotter and Radar Scope.  The developer of Storm Spotter is another OU meteorology student and I highly recommend his app.  Radar Scope does have a few things like spotter network, but it does not have any form of surface street map.  Storm Spotter uses google maps which makes exact location or storm chasing much easier.

Another field essential is taking notes.  There are many note apps out there and most do about the same things with different degrees of reliability.  For quick sketches I use Penultimate and for class notes I use Note Taker HD, which has a 'zoom box' that lets me write large with my stylus (the Pogo Sketch) and it is normal sized writing on the page.  Sundry notes is also around, but has not received any use by me for some time.

File sync is also an essential and can be done with Dropbox.  I already loved this service and the mobile app made life easier! Now I can save notes from the field and they instantly sync to my computer at home, my phone, and my laptop.

For field math there is Wolfram alpha (cloud service), Quick Graph, and many apps like MathTasks that do simple calculations on the fly.

Sometimes I'll use a GPS utility to mark out rough locations on a map or even the iPad ArcGIS to get an approximate distance/area.

Finally, we all need files and file editing in the field.  I use Papers to keep my scientific paper library with me at all times.  In the field or at a conference it's easy to find that paper you need a snippet from and email it directly to the interested party/conference goer.  Annotating PDF files is easy with iAnnotate PDF and viewing large files is nice with GoodReader (though Books now does this also).

While all these apps are productivity, you can bet all iPad owners have their favorite music service loaded, Netflix, and other entertainment too.  While I do love using my iPad it does have overheating issues when working out in direct sun on a hot day.  The screen is great at letting solar radiation in, and trapping the re-emitted IR inside the device,  shutting it off in ~10 minutes.  What can you do? Use a case with an open back and keep the screen shaded.  I'm not quite ready to quit carrying paper notes all together, but it's getting close and my daily/travel backpack is getting lighter every year.  Read about other great apps for large scale studies used in Pompeii here.

Images are property Apple.

The Vuvuzela: An Annoying Horn but a Fun Filter Project!

As we've watched the world cup matches over the past weeks everyone has been annoyed by the droning hum of the vuvuzela.  Everyone in the crowd blowing on one of these pipes makes life for our ears unpleasant.  What can you do though?

While at SciPy 2010 this week we saw a tutorial about signals with Python.  Another student and I talked about filtering out the drone and after several late nights of hacking it worked! The principle is simple, block the frequency of the horn and it's harmonics.  To do this we use a notch filter that rejects the signal from a certain frequency range.

The code ( is available and is a short script to read in, filter, display, and write out the files.  Below I show an example of the signal and power spectral density before filtering (left) and after filtering (right).  There are also links to the audio files.  I found three example files and filtered them with three different filter widths (5,10,25 Hz). All runs are available at , but that link will disappear and I'll then post a more permanent page after some tweaking with the project.  Be sure to listen to example 3 before and after the 5Hz width filter.