Anybody who has set up a satellite TV antenna will tell you that alignment is critical when picking up a signal from space. With a satellite dish it’s a straightforward task to tweak the position, but what happens if the dish in question is out beyond the edge of the Solar System?
We told you a few days ago about this exact issue currently facing Voyager 2, but we’re guessing Hackaday readers will want to know a little bit more about how a 50+ year old spacecraft so far from home can still sort out its antenna. The answer lies in NASA Technical Report 32-1559, Digital Canopus Tracker from 1972, which describes the instrument that notes the position of the star Canopus, which along with that of the Sun it can use to calculate the antenna bearing to reach Earth. The report makes for fascinating reading, as it describes how early-1970s technology was used to spot the star by its specific intensity and then keep it in its sights. It’s an extremely accessible design, as even the part numbers are an older version of the familiar 74 logic.
So somewhere out there in interstellar space beyond the boundary of the Solar System is a card frame full of 74 logic that’s been quietly keeping an eye on a star since the early 1970s, and the engineers from those far-off days at JPL are about to save the bacon of the current generation at NASA with their work. We hope that there are some old guys in Pasadena right now with a spring in their step.
Read our coverage of the story here.
Important safety tip: When you’re sending commands to the second-most-distant space probe ever launched, make really, really sure that what you send isn’t going to cause any problems.
According to NASA, that’s just what happened to Voyager 2 last week, when uplinked commands unexpectedly shifted the 46-year-old spacecraft’s orientation by just a couple of degrees. Of course, at a distance of nearly 20 billion kilometers, even fractions of a degree can make a huge difference, especially since the spacecraft’s high-gain antenna (HGA) is set up for very narrow beamwidths; 2.3° on the S-band channel, and a razor-thin 0.5° on the X-band side. That means that communications between the spacecraft and the Canberra Deep Space Communication Complex — the only station capable of talking to Voyager 2 now that it has dipped so far below the plane of the ecliptic — are on pause until the spacecraft is reoriented.
Luckily, NASA considered this as a possibility and built safety routines into Voyager‘s program that will hopefully get it back on track. The program uses the onboard star tracker to get a fix on the bright star Canopus, and from there figures out which way the spacecraft needs to move to get pointed back at Earth. The contingency program runs automatically several times a year, just in case something like this happens.
That’s the good news; the bad news is that the program won’t run again until October 15. While that’s really not that far away, mission controllers will no doubt find it an agonizingly long time to be incommunicado. And while NASA is outwardly confident that communications will be restored, there’s no way to be sure until we actually get to October and see what happens. Fingers crossed.
Getting a closer look at the Moon isn’t particularly difficult; even an absolute beginner can point a cheap telescope towards our nearest celestial neighbor and get some impressive views. But if you’re looking to explore a bit farther, and especially if you want to photograph what you find out there amongst the black, things can get complicated (and expensive) pretty quick.
While building this 3D printed automated telescope designed [Greg Holloway] isn’t necessarily cheap, especially once you factor in what your time is worth, the final product certainly looks to be considerably streamlined compared to most of what’s available in the commercial space. Rather than having to lug around a separate telescope, tripod, motorized tracker, and camera, you just need this relatively compact all-in-one unit.
It’s taken [Greg] six months to develop his miniature observatory, and it shows. The CAD work is phenomenal, as is the documentation in general. Even if you’re not interested in peering into the heavens, perusing the Instructables page for this project is well worth your time. From his tips on designing for 3D printing to information about selecting the appropriate lens and getting it mated to the Raspberry Pi HQ Camera, there’s a little something for everyone.
Of course if you are looking to build your own motorized “GOTO” telescope, then this is must-read stuff. [Greg] has really done his homework, and the project is a fantastic source of information about motor controllers, wiring, hand controllers, and the open source firmware you need to tie it all together. Many of the ideas he’s outlined here could be applicable to other telescope projects, or really, anything that needs to be accurately pointed to the sky. If you’d like to get started with night sky photography and aren’t picky about what kind of things you capture, we’ve seen a number of projects that simply point a camera towards the stars and wait for something to happen.
[Thanks to Eugene for the tip.]
Keeping track of position is crucial in a lot of situations. On Earth, it’s usually relatively straight-forward, with systems having been developed over the centuries that would allow one to get at least a rough fix on one’s position on this planet. But for a satellite out in space, however, it’s harder. How do they keep their communications dishes pointed towards Earth?
The stars are an obvious orientation point. The Attitude and Articulation Control Subsystem (AACS) on the Voyager 1 and 2 space probes has the non-enviable task of keeping the spacecraft’s communication dish aligned precisely with a communications dish back on Earth, which from deep space is an incomprehensibly tiny target.
Back on Earth, the star tracker concept has become quite popular among photographers who try to image the night skies. Even in your living room, VR systems also rely on knowing the position of the user’s body and any peripherals in space. In this article we’ll take a look at the history and current applications of this type of position tracking. Continue reading “Star Trackers: Telling Up From Down In Any Space”
If you want to take beautiful night sky pictures with your DSLR and you live between 15 degrees and 55 degrees north latitude you might want to check out OpenAstroTracker. If you have a 3D printer it will probably take about 60 hours of printing, but you’ll wind up with a pretty impressive setup for your camera. There’s an Arduino managing the tracking and also providing a “go to” capability.
The design is over on Thingiverse and you can find code on GitHub. There’s also a Reddit dedicated to the project. The tracker touts its ability to handle long or heavy lenses and to target 180 degrees in every direction.
Continue reading “OpenAstroTracker Turns Your DSLR Into An Astronomy Instrument”