Today I gave a lunch talk at the Harvard-Smithsonian Center for Astrophysics on some work I’ve been doing for the Breakthrough Starshot project. In particular, I’ve been trying to figure out how to make sure the lightsail stays on the laser beam as it is accelerated. In the video below, I talk about some analysis on different beam and sail configurations and thier stability properties. You can also check out a draft of the paper on ArXiv for all of the gory mathematical details.
I just got back from the 2017 AIAA SciTech Conference in Grapevine, Texas. The conference was a great opportunity to learn about a whole bunch of interesting small satellite and UAV work going on around the world. I presented two papers: one on spacecraft inertia estimation that grew out of my PhD work on KickSat, and one on some new micro aerial vehicle (MAV) perching work I’m doing in my postdoc at Harvard. The picture below shows the wind tunnel test rig I built to measure the aerodynamic coefficients (lift, drag, and pitching moment) of our MAV prototypes. Check out the papers and slides from my talks if you’re interested.
I just got back from the 2016 AIAA Space Conference in Long Beach, California where I presented a paper that grew out of some work I did on KickSat related the classic flat-spin recovery problem. A flat spin occurs when a spacecraft that is intended to spin about its minor axis of inertia (long axis) finds itself spinning about its major axis of inertia (short axis). This problem dates back all the way to Explorer 1, the first satellite launched by the U.S., and a variety of solutions have been proposed over the years. Most of them, however, are not able to control the polarity of the spacecraft as it comes out of the flat spin, possibly resulting in a 180 degree rotation from the desired orientation.
I discovered a Lyapunov-based controller law that solves this problem, guaranteeing that a spinning spacecraft will return to the desired final spin orientation. In math lingo, the control law is almost-globally asymptotically stabilizing. If you’re still with me, have a look at the paper. Here’s a plot of the trajectory traced out by the angular momentum vector of a satellite during a flat spin recovery using the new controller:
I spent the past week with an awesome organization called Clubes de Ciencia teaching university and high school students in Xalapa, a small city in the state of Veracruz in Mexico. My “club” was called ¡3, 2, 1 Despegue! (3, 2, 1, Liftoff!), and we covered the basics of orbit mechanics, spacecraft design, and satelite communication. Two big highlights of the week (in addition to the Mexican food) were listening to signals from a CubeSat and launching a high altitude balloon that eventually topped out at over 103,000 feet! Check out the footage of the launch with great views of the city below:
An article I wrote on Breakthrough Starshot for IEEE Spectrum went online today. I tried to give some insight into the engineering challenges that the project faces without going too deep into technical details. A challenging journey lies ahead and I’m very excited to be a part of it!