NASA iSAT: Rebuilding a Lost Satellite Tracker from Scratch and Debuting It at SXSW

NASA iSAT: Rebuilding a Lost Satellite Tracker from Scratch and Debuting It at SXSW

CLIENTNASA Science Mission DirectoratePILLAREngineeringSERVICESJavaScript / Algorithm Translation / 3D Visualization / Browser-Based Computation

Highlights

  • Rebuilt a lost NASA satellite tracking application from scratch after the original codebase was no longer available
  • Translated orbital mechanics algorithms from MATLAB to JavaScript, enabling real-time computation of thousands of satellite positions directly in the user’s browser
  • Integrated the SGP4 implementation with the open-source Cesium Virtual Globe for interactive 3D visualization of satellite tracks over Earth
  • Adopted by educators as a classroom STEM tool for math and physics instruction
  • Debuted at the NASA Tent at South by Southwest 2013; presented at NASA’s Earth Day exhibit in Washington, DC, in 2014

Challenge

The website science.nasa.gov had a satellite-tracking application that educators and members of the public had come to rely on, particularly for math and physics instruction. Teachers used it to bring orbital mechanics into the classroom in a way that was visual, interactive, and connected to real NASA missions. Then it stopped working. The application had gone unmaintained, and by the time NASA’s Science Mission Directorate began receiving requests to restore it, the original code was gone.

The emails from the public and educators kept coming. The application had been genuinely useful, and its absence was noticed. NASA needed it rebuilt, but there was nothing to rebuild from. The algorithms it had used, based on the SGP4 simplified perturbation models that NASA and NORAD use to track satellites, were available in both FORTRAN and MATLAB. Nothing suitable for the web existed. The solution would have to be written from scratch, starting with the mathematics.

Action

V! Studios’ engineers began by going back to first principles. They worked with subject-matter experts at NASA to understand the orbital mechanics involved, then researched the SGP4 models that underpin satellite tracking at the agency and NORAD levels. With no existing web-ready implementation to work from, the team translated the algorithms from MATLAB to JavaScript, a translation that required not just converting syntax but also understanding the mathematics well enough to ensure the implementation produced accurate results at the speed the application required.

The JavaScript implementation was a deliberate architectural choice. Running the orbital computations in the user’s browser rather than on a server meant the application could handle thousands of simultaneous users without the computational load scaling against a back-end infrastructure. It also meant the calculations could update continuously in real time, which is what makes the application genuinely useful for showing satellite motion rather than static position.

The team integrated the new SGP4 implementation with the open-source Cesium Virtual Globe, a 3D geospatial platform, to display satellite tracks over Earth interactively. The result was an application that could show thousands of satellites moving simultaneously in three dimensions, with all computation happening locally in the browser.

Result

The new implementation, named iSAT, was received so wellwell enough that NASA’s Science Mission Directorate sent V! Studios’ lead developer to present its debut at the NASA Tent at South by Southwest in 2013, one of the highest-profile public technology and culture events in the country. In April 2014, the developer presented iSAT again at NASA’s Earth Day exhibit in Washington, DC, where teachers and parents commented on its educational value and children asked whether satellites were faster than cheetahs.

The 3D visualization made satellite motion tangible in a way that static charts and tables cannot. Educators had the tool they had been asking for. The public had a window into the real-time mechanics of what is orbiting the Earth. And all of it ran in the browser, fast enough to show thousands of objects simultaneously.

“You have all done an incredible amount of work in just a few months for an event that is likely to be the largest outreach event for NASA in the foreseeable future. You should be proud of what you have done. I am proud of all of you, and I am humbled to be part of such a team.”NASA Science Communications and Public Engagement

Why It Matters

The original application was gone. There was no codebase to restore, no implementation to update, no documentation to work from. V! Studios rebuilt it by understanding the mathematics well enough to re-implement orbital mechanics from a scientific specification, in a language and architecture chosen specifically for how the application would be used, not just whether it would work.

That is a different problem than standard application development. It required engineers who could read the scientific literature, engage with NASA subject-matter experts at the level of the underlying physics, and make architectural decisions based on performance constraints that did not exist in any brief. The MATLAB-to-JavaScript translation alone required the kind of mathematical fluency that is not a standard part of a web development skill set.

iSAT also captures an important aspect of what V! Studios values in engineering work: the end user matters. The application was rebuilt because educators and students had lost a tool they were actually using in classrooms. The SXSW debut and the Earth Day exhibit were not promotional exercises; they were proof that the rebuilt tool worked for the people it was built for. A child asking whether a satellite is faster than a cheetah is the right outcome for a NASA public engagement tool. It means the application did its job.