Satellite Lost and Found in Space


SkyCube, a crowd-funded nanosatellite built to engage the public in space exploration, has been deployed from the International Space Station. Now its creators are anxiously waiting to establish two-way contact — and advanced amateurs can help.

Update: The team is finally hearing from SkyCube again. After weeks of radio silence, the Central California ground station heard from the satellite and was able to track down its location. SkyCube is operational, though it's likely that the solar panels didn't unfold all the way. The team is now continuing to attempt contact with the satellite, sending commands that will fully unfurl the solar panels. Read the full SkyCube status update.

Last week astronauts aboard the International Space Station deployed 33 CubeSats into orbit around Earth, the largest number of nanosatellites deployed in a single mission. One of these deployed was SkyCube, a labor of love that took a year and a half to develop, build, and launch into orbit. Now we're trying to establish two-way contact with the satellite — if you have a large scope and want to help, scroll down to "Spot the Satellite."

The CubeSats were deployed a few at a time from the International Space Station. Watch the deployment of five CubeSats here, including SkyCube:

SkyCube is a 1U CubeSat measuring 10 centimeters on a side. It’s the size of a toaster, yet it carries a computer board, a radio and antenna, solar panels, a rechargeable battery pack, three small cameras, and a large balloon that will ultimately pull the satellite out of orbit at the end of its useful life.

We built SkyCube because — as amateur astronomers — we were tired of being spectators to space exploration. We decided to participate. SkyCube was 100% crowd-funded and once active, will let anyone take pictures of Earth and tweet from space. Though the journey was twice as expensive and twice as long as we expected, on January 9, 2014, the Antares/Cygnus "Orb-1" rocket finally carried SkyCube and its 32 companion CubeSats on its resupply mission to the International Space Station, where the satellites would be deployed six weeks later.

Immediately after deployment, the International Space Station (ISS) and the just-released CubeSats all passed into Earth's shadow. Forty-five minutes went by before the solar panels and radio antennas could unfold.

The anticipation built. SkyCube had been in cold and dark storage for four months, and we had never tested how the batteries would hold charge over such a long time. They might have discharged, or they might have required several orbits to recharge enough to fire up the burnwires and release the solar panels. We just didn’t know.

Making Contact

CubeSat deployer
Japanese astronaut Koichi Wakata floats beside the CubeSat deployer. SkyCube is inside.
Nanoracks
The first possible contacts were with a ground station in Sydney, Australia, but network issues on the ground prevented that station from connecting to our server. The subject line of the email I read when I woke up Friday morning was “No joy.”

Later that morning, at 8:30 a.m. PST, the SkyCube was scheduled for its first pass over a North American ground station. We sent "get status" commands at 450 MHz every 10 seconds. For the first minute or two, we got no response. Then we heard a distinct 915 MHz signal coming back. (SkyCube receives and transmits on two different frequencies.) The signal wasn't strong, but there was definitely a signal — and it disappeared when ISS crossed over the horizon.

We observed the same thing from a different ground station on Friday afternoon. The radios achieved carrier lock, bit lock, and bit sync. So unless somebody else was broadcasting a 57.6 kbps BPSK-modulated signal at 915 MHz from the same point in the sky, at the same time, and stopped just as ISS went over the horizon, then that signal was almost certainly SkyCube.

CubeSats next to the International Space Station
NASA
The folks running the ground station network were convinced, and I trusted them enough to feel comfortable saying publicly, “SkyCube is alive.” If the batteries had died, or the solar panels not deployed, or the processor board zapped, or the radio cables shaken loose, or any of the multitude of things that could have gone wrong . . . we would have heard nothing. And we definitely did not hear nothing.

However, since that time, we haven’t yet had further contacts, and none of the initial contacts resulted in a completely decoded AX.25 packet.
However, all the antennas were pre-programmed to point at the ISS during ISS passes. Since that time, the satellites have all drifted several
hundred km from ISS, so our pointing is certainly wrong now.

Celestrak.com published orbital elements for five new objects, one of which is almost certainly ours. If you plot these objects on a map, all are several hundred kilometers from the ISS now, clustered together in a group, following the Planet Labs Flock-1 satellites, which were deployed the day before ours.

Spot the Satellite

SkyCube
SkyCube fully assembled and packed for launch, exposing solar cells on the outer sides of its solar panels.
Southern Stars
If you're using our Satellite Safari app to track these satellites, these objects will appear in the "Stations" group under the Search menu.

In the meantime, here’s a challenge for amateur astronomers with larger telescopes and satellite-observing experience: try looking for SkyCube and the other CubeSats. Yes, it’s actually possible to image a 10-centimeter object in low-earth orbit with a large (16" and up) amateur telescope.

The best technique requires a wide-field (say, 30-arcminute) CCD camera. Park your telescope at a point where the CubeSats are expected to pass, then time a 60-second exposure to begin shortly before the CubeSats pass through. They’ll appear as faint streaks on the CCD image. Note: I've never tried this personally, but I've seen other amateurs’ CCD images of CubeSats taken in this way.

It might even be possible to see CubeSats visually with a large enough telescope. Published visual magnitude standards for existing 1U CubeSats list magnitues of 10 at 1,000 km range and 50% illumination. If you're interested in taking up this challenge, please contact us at skycube@southernstars.com.

In the meantime, we'll continue to find and contact our satellite. It often takes first-time CubeSat teams several weeks to establish reliable communication with their satellites. For many, that never happens. Half the CubeSats deployed from last November's ORS-3 launch have never been heard from in space. While we haven’t yet achieved reliable two-way communication, we do seem to be off to a good start. And we're certainly willing to accept any help that's offered. The best thing about these efforts is that they're team efforts, and we hope to share more news with you soon — check SkyCube’s Kickstarter page for updates.


Tim DeBenedictis was one of the two principal designers behind the award-winning SkySafari mobile astronomy apps. He is SkyCube's founder/owner and wrote about the potential for public entry into orbit using CubeSats in the November 2013 issue of Sky& Telescope.

7 thoughts on “Satellite Lost and Found in Space

  1. Charles D Phillips

    Tim – Hopefully we can uniquely identify SkyCube and establish communications. Between various observers and other enthusiasts we do bring a lot of resources to the effort.

  2. Anthony Barreiro

    Please forgive a naive question. Why are the cubesats drifting away from the ISS? If they were in the space station, moving at the same velocity as the space station, Newton’s first law would suggest that they would continue traveling at the same speed and in the same direction as the space station. Did an astronaut or a robot give the cubesats a mighty heave to start them moving away from the station? Or does the ISS have engines that keep it moving faster than its launch momentum would carry it? By the way, I hope the team is able to contact this little satellite. I imagine it would feel like operating a radio-controlled airplane on steroids!

  3. Frank Reed

    Anthony, small objects in LEO are strongly influenced by air resistance at that altitude. Even the ISS experiences substantial air resistance, and as you may know, if its orbit were not periodically boosted it would re-enter the atmosphere and be destroyed in less than two years. Of course gravitation causes the same acceleration on all objects regardless of mass, but air resistance varies from one object to another depending on surface area relative to mass and other factors. The prototype case is Galileo’s hammer and feather. You know they fall very differently at the Earth’s surface. That’s also true in low orbit. If you were to release a hammer and a feather in Low Earth Orbit, the feather would be found in a significantly lower orbit every day due to air resistance, and as a result it would rapidly move away from the hammer since lower orbits have shorter orbital periods. In a week the feather could be a thousand miles from the hammer (though only a few miles lower in altitude). Same thing goes on with small objects released from manned spacecraft. And that’s why inflating a balloon (as described in the article) can bring one of these small satellites down in a relatively controlled fashion. There are other factors at work on relative satellite motion, but this is the main factor for small satellites and also orbital debris.

  4. Frank Reed

    I would say that there is no question that backyard observers with relatively small telescopes should be able to see these satellites on favorable passes (near the zenith with good Sun illumination). I myself have seen Vanguard 1, the oldest satellite still in orbit, launched March 17, 1958, with a 6" refractor, and it was not a difficult observation. Vanguard is not much bigger (about 16 cm), and it’s much higher up than these little cubesats. In fact with really good conditions, I would not be surprised if these cubesats might be observed with 7×50 binoculars. Sure they’re small, but when conditions are right they’re in full sunlight against a pitch black sky. And although the relatively rapid motion across the sky is a killer for a camera tracking the stars, it makes visual observations that much easier.

  5. Anthony Barreiro

    Thanks Frank. I knew that the ISS needs to be boosted to a higher orbit to keep it from burning up in the atmosphere, but I didn’t realize that atmospheric drag is such a ubiquitous phenomenon. And I hadn’t considered that Galileo’s hammer and feather might be relevant to satellites in low Earth orbit! I still hope somebody or something gives these little satellites a good shove to get them started.

  6. rocksnstarstom hoffelder

    That’s what immediately came to mind when reading the first sentence. Seems like it would have been better to stick them in/on one container, but maybe interference would be a problem.

  7. Frank Reed

    Yes, Anthony, they do give them a good shove. There’s a neat little ejection system that uses the robot arm on the Japanese Kibo module. I don’t know the details (spring-loaded? A little airgun?), but they "pop" out with a small initial velocity to get them clear of the station and then the differential air resistance that I described previously does the rest. Note that if air resistance did not exist, and if neither the station nor the ejected satellite maneuvered after release, then they would bump into each other again an orbit later. None of this is new. The Russians routinely threw trash overboard from the Mir space station in the 1990s. The huge advances in computer miniaturization has made it practical to use this same process for economical, albeit relatively unimportant, small satellites. At this altitude small satellites and debris, especially low density debris constitutes no serious threat as orbital debris precisely because it spirals down out of orbit so quickly thanks to air resistance.

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