On an October night in 1847, a telescope on the roof of the Pacific National Bank building on Nantucket Island was trained onto the deep black sky. At the eyepiece was an accomplished amateur astronomer on the verge of a major discovery — a new comet, one not recorded in any almanac. The comet, which we today know by the dry designator C/1847 T1, is more popularly known as “Miss Mitchell’s Comet,” named after its discoverer, a 29-year old woman named Maria Mitchell. The discovery of the comet would, after a fashion, secure her reputation as a scholar and a scientist, but it was hardly her first success, and it wouldn’t be her last by a long shot.
Last week, the Rosetta spacecraft crashed into comet 67P/Churyumov-Gerasimenko after orbiting it since 2014. It was supposed to do that: the mission was at an end, and the mission designers wanted to end it by getting a close look at the surface of the comet. But this raises an interesting problem: how do you get a device that is designed to never stop to actually stop?
Continue reading “How To Hack A Spacecraft To Die Gracefully”
When the big annual meteor showers come around, you can often find us driving up to a mountaintop to escape light pollution and watching the skies for a while. But what to do when it’s cloudy? Or when you’re just too lazy to leave your computer monitor? One solution is to listen to meteors online! (Yeah, it’s not the same.)
Meteors leave a trail of ionized gas in their wake. That’s what you see when you’re watching the “shooting stars”. Besides glowing, this gas also reflects radio waves, so you could in principle listen for reflections of terrestrial broadcasts that bounce off of the meteors’ tails. This is the basis of the meteor burst communication mode.
[Ciprian Sufitchi, N2YO] set up his system using nothing more than a cheap RTL-SDR dongle and a Yagi antenna, which he describes in his writeup (PDF) on meteor echoes. The trick is to find a strong signal broadcast from the earth that’s in the 40-70 MHz region where the atmosphere is most transparent so that you get a good signal.
This used to be easy, because analog TV stations would put out hundreds of kilowatts in these bands. Now, with the transition to digital TV, things are a lot quieter. But there are still a few hold-outs. If you’re in the eastern half of the USA, for instance, there’s a transmitter in Ontario, Canada that’s still broadcasting analog on channel 2. Simply point your antenna at Ontario, aim it up into the ionosphere, and you’re all set.
We’re interested in anyone in Europe knows of similar powerful emitters in these bands.
As you’d expect, we’ve covered meteor burst before, but the ease of installation provided by the SDR + Yagi solution is ridiculous. And speaking of ridiculous, how about communicating by bouncing signals off of passing airplanes? What will those ham radio folks think of next?
[Steve] drives spacecraft for a living. As an engineer at the Jet Propulsion Laboratory, he’s guided probes to comets, asteroids, Mars, and Jupiter, figured out what happens when telemetry from these probes starts looking weird, and fills the role of the Space Hippy whenever NASA needs some unofficial PR.
Like most people who are impossibly cool, [Steve]’s career isn’t something he actively pursued since childhood. Rather, it’s something that fell in his lap. With qualifications like building a robotic computer to typewriter interface, a custom in-car navigation system in the late 80s, and a lot of work with an Amiga, we can see where [Steve] got his skills.
The earliest ‘hack’ [Steve] can remember was just that – an ugly, poorly welded sidecar for his bicycle made in his early teens. From there, he graduated to Lasertag landmines, Tesla coils, and building camera rigs, including a little bit of work on Octopussy, and a rig for a Miata. It helps when your dad is a cinematographer, it seems.
In college, [Steve] used his experience with 6502 assembler to create one of the first computerized lighting controllers (pre-DMX). After reading a biography on [Buzz Aldrin], [Steve] realized doing his thesis on orbital rendezvous would at least be interesting, if not an exceptionally good way to get the attention of NASA.
Around this time, [Steve] ran into an engineering firm that was developing, ‘something like Mathematica’ for the Apple II, and knowing 6502 assembly got him in the door. This company was also working to get the GPS constellation up and running, and [Steve]’s thesis on orbital mechanics eventually got him a job at JPL.
There’s several lifetimes worth of hacks and builds [Steve] went over at the end of his talk. The highlights include a C64 navigation system for a VW bug, a water drop high voltage machine, and a video editing system built from a few optical encoders. This experience with hacking and modding has served him well at work, too: when the star sensor for Deep Space 1 failed, [Steve] and his coworkers used the science camera as a stand in navigation aid.
One final note: Yes, I asked [Steve] if he played Kerbal Space Program. He’s heard of it, but hasn’t spent much time in it. He was impressed with it, though, and we’ll get a video of him flying around the Jool system eventually.