ISEE-3: On Track To Come Home

Intended trajectory from ICE team in 1986 (blue), 2001 ephemeris of ISEE-3 (white) and current ephemeris (red/green). Click to embiggen.

When last we heard of the progress of commanding the derelict ISEE-3 satellite into stable orbit between the Earth and the sun, the team had just made contact with the probe using the giant dish in Arecibo, sent a few commands, and started gathering data to plot where the spacecraft is and where it will be. A lot has happened in a week, and the team is now happy to report the spacecraft is alive and well, and much, much closer to the intended trajectory than initially believed.

Before last week, the best data on where ISEE-3 was heading was from a 13-year-old data set, leaving the project coordinators to believe a maneuver of about 50-60  m/s was necessary to put the spacecraft into the correct orbit between the Earth and the sun. With new data from Arecibo, that figure has been reduced to about 5.8 m/s, putting it extremely close to where the original ICE navigation team intended it to go, all the way back in 1986. This also gives the team a bit of breathing room; the original planned maneuver to capture the spacecraft required nearly a third of the available fuel on board. The new plan only requires the spacecraft expend about 5% of its fuel stores. This, of course, brings up the idea of continuing the planned mission of the rebooted ISEE-3 beyond the Earth-Sun L1 point, but that is very much putting the cart before the horse.

Of course, getting ranging data of the spacecraft is only a small part of what has happened with the ISEE-3 part this week. Thanks to the ‘away team’ sent to Arecibo to install hardware and attempt to make contact with the satellite, both transceivers are working, telemetry is being downloaded from the probe, and work has begun on refining the exact position of ISEE-3 to compute where and when the spacecraft needs to make its maneuver.

Regular Hackaday feature and software defined radio god [Balint] was on hand with the away team at Arecibo to install his company’s SDR unit on the largest dish on the planet. His happy dance of the first data from ISEE-3 made the blog rounds, but the presentation (PDF) and photo gallery tell the story of working on the largest dish on the planet much better.

There’s still a lot of work to be done by the ISEE-3 team as they figure out how best to capture the spacecraft and prepare for the burn in the following week. They should have the exact orbit of ISEE-3 nailed down early this week, and after that, ISEE-3 could on a path back home in less than two weeks.

15 thoughts on “ISEE-3: On Track To Come Home

  1. Like dragging an old car out of a barn, pouring a bit of gasoline down the carb then turning the key and having it fire up before even turning over one revolution.

    Won’t be happening with that recently abandoned satellite where the operators profligately *wasted* all its remaining fuel with a 17 hour burn, just to make sure it was good and done for and no longer usable.

    Now that they have the thing, what can they *do* with it? Can they sift data out of its decades old sensors that the original ground control equipment for it wasn’t able to?

    1. Even if there is no onboard memory, just parking it so that it can be retrieved easily-ish (to take a look at what a deep space probe looks like after 40ish years) would be a boon.

      1. Derelict craft parked in Earth orbit usually vent fuel and other volatiles to prevent explosions and debris which could lead to Kessler Syndrome. Satellites at end of life can’t just be left around full of fuel if they can’t be dropped back into the atmosphere safely.

  2. I am impressed and amazed! I had no doubts that this could be done; my only doubt was whether there was going to be enough time to raise the money, build the equipment and any needed software, get air-time on the dish (etc) – I am glad to be proven wrong.

    On a side note – is the Arecibo dish is looking a bit neglected, or is it just me?

    I mean, its obviously working, and the control areas (and installed hardware) all look well cared for. The dish itself, though, looks like something you’d see on an urbex site or such. Parts of it (receiver antennas, etc) look ok – but the dish, suspension system, etc – they look like they are almost falling apart (lots of rust, etc). I realize they are in a tropical jungle area, and I also realize that the funding for the place is probably limited, plus the thing is huge…but still…

    I guess it just depresses me that one of our greatest assets here on earth is left to decay (that dish should be a shiny beacon for the world!), while we as a species spend so much of our resources on so many other petty issues (mainly wars and entertainment) that in the ultimate long run don’t amount to a hill of beans.

    These guys managed to spend an inconsequential amount of money (relatively speaking, of course) to pull off what was thought to be nearly impossible only a scant few months ago. Imagine what we as a species could do if we really focused our resources and energies toward the stuff that really should matter (for instance, figuring out how to get our asses off this rock and quit being sitting ducks for the next large asteroid from nowhere).

    1. Aricebo is ancient compared to how we build radio telescopes now. Yes, it’s a big ass bowl but we now use arrays of smaller dishes to create a high resolution image. And they have the added benefit of large sweeping movements. So sadly, Aricebo isn’t really kept up with like it used to be.

      1. Does Arecibo at least have an advantage when being used as a transmitter? I figure when recieving with a big array you have some more leeway because you can align everything in post processing but I’d expect one would need some mighty expensive hardware to synchronize everything correctly when transmitting!

        All that said, a ham has detected the satellite’s signal with an 8 foot dish :D

        1. There are very few astronomy radars, and as far as I know, none use a large array of transmitters. When transmitting, you have to assure that all signals you send are perfectly in sync, or you loose accuracy of your radar VERY quickly.

          And yes, because of the size of the dish (305m in diameter) and the power of the transmitters, we have a tremendous advantage. While a few radars have higher ERP than us, that is pretty much only at X-band (8-9GHz), where our reflector isn’t quite as perfect.

      2. We (Arecibo Observatory) definitely have a place in astronomy. Certain types of astronomy (so called Single Pixel astronomy) study point-sources, where imaging would essentially be pointless. For these types of sources, signal-to-noise is very important, and the best way to increase that is using more collecting area, i.e. bigger dish.

        So far, no stand-alone array has anywhere near the collecting area of Arecibo, and from time to time, Arecibo participates with these arrays (to improve collecting area) in a technique called VLBI or Very Long Baseline Interferometry.

        However, you are correct, it is not kept up as much as we would like. Our funding from the government is shrinking, costs are increasing, and the constant demand for science (which keeps us funded) means taking needed time for maintenance is getting harder and harder to do. Not to mention we only have something like 20-30 employees in platform maintenance, which is surely smaller than even some bridge painting crews (which is a very good comparison to platform maintenance at Arecibo). The observatory was constructed in 1963, and is now 50 years old. The fact that it is in as good a shape as it is now is amazing. It has survived numerous hurricanes and earthquakes, so we all hope to see it outlast us.

    2. Also, this big rock we are on is tethered to us until we figure out a life support system for the transportation to another planet (which will be uncomfortable as hell.) Extinction of the species is likely since our existence relies on the unique circumstances this rock is in.

    3. > On a side note – is the Arecibo dish is looking a bit neglected, or is it just me?

      It’s a 50 year old, thousand foot diameter metal dish in the middle of a jungle. The fact that it’s still there suggests it’s well taken care of.

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