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A nano-satellite that lets you take Earth images and "tweet" from space, then inflates a visible balloon, and de-orbits cleanly.
2,711 backers pledged $116,890 to help bring this project to life.

Searching for SkyCube

Posted by Tim DeBenedictis (Creator)

Nine days ago, five objects were released from the ISS. NORAD assigned them tracking numbers 39567 thru 39571. One of them is certainly SkyCube, and it's the only one that transmits on 915 Mhz. We detected a clear 915 MHz signal near ISS the morning after SkyCube deployed, and a second time on an iSS pass over a different ground station later that afternoon.

 Since then, those objects have drifted hundreds of miles apart, and thousands of miles from ISS. Each ground station can really only track one object at a time - unless they're close enough to fit into the station's antenna beam. And then you don't know which one you've detected.

Twice last week, a 915 MHz signal was detected by two different ground stations (Australia on 3 March at 10:46 UTC; California on 4 March at 21:57 UTC). Both signals came at times when 39570 was passing over the ground stations that detected them. That's suggestive, but not conclusive.

On Wednesday, NASA, - and Satellite Safari - assigned identifications to objects 39567 - 71 in the order they were released from the ISS. Those identifications are surely wrong. The satellites swapped order since their release; they have different masses and sizes, so atmospheric drag affects them differently. On some passes, we may have been trying to communicate with the wrong object(s).

So how do we tell who is who? We've been in contact with the chief engineer of Lithuania's satellites, LitSAT-1 and LithuanicaSAT, deployed at the same time as SkyCube. Laurynas writes:

"We noticed NORAD associated numbers to the satellites according to the order they were released from the NanoRacks deployer. This is of course not accurate since sats have taken other positions in orbit. For Your notice, it seems that two Lithuanian birds have received good TLE references from german ham radio operator Mike Ruprecht, see his webpage. We are now almost continuously tracking our LituanicaSAT-1 with NORAD catalouge no 39568U with good results."

Mike Rupprecht's identifications are: LITSAT-1 = 39568, LITUANICA = 39569, UAPSAT = 39571. These identifications disagree with NASA's. At this point both may still be wrong.

The process is like trying to figure out who's who in a group of gnats flying around inside a football stadium, by listening to each gnat hum a different tune, for a few minutes each day. It's going to take a while to sort them out.

In the meantime

Many of you are amateur radio operators who've asked for information to help track SkyCube's beaconing signals. Here's what SkyCube should be doing:

Every 3 minutes, SkyCube broadcasts its telemetry at 915 MHz with BPSK modulation at 9600 baud. The data is in a single AX.25 packet containing human-readable ASCII text, prefixed and followed by 2 seconds of preamble. The entire telemetry "tweet" should last about 4 seconds, and repeat every 3 minutes.

Today, we are releasing the first public beta of Scott Cutler's SeeDeR software. It's a Windows program that can decode AX.25 radio transmissions using inexpensive USB software defined radio (SDR) devices. You can also download a pre-recorded sample of a SkyCube "telemetry tweet". This is what to listen for.

SeeDeR playing back pre-recorded SkyCube "telemetry tweet"
SeeDeR playing back pre-recorded SkyCube "telemetry tweet"

Finally, many of you are amateur astronomers. As Sky & Telescope mentioned, experienced satellite observers may be able to image the CubeSats with a CCD camera or even visually, with a large (16"+) backyard telescope and dark skies.

Please report any radio or optical detections to Please include the date/time of your observations, your observing location, and equipment used. Please include any images, SDR recordings, screenshots of waterfall diagrams, etc.

We'll continue efforts to locate SkyCube and establish communication this week. Patience and persistence are the name of the game. This is just the beginning.

-Tim, Scott, Rouslan, Mark, and the rest of team SkyCube


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    1. Missing avatar

      Montgomery A. Lee on

      Anybody know anything more? No updates in 3 months. Is SkyCube dead?

    2. Missing avatar

      Greg Parikh on

      Are there any updates at all?
      Something would be nice

    3. josep saldaña cavallé on

      SkyCube signal?! Radioamateur Dmitry Pashkov @UB4UAD heard this today at 915 MHz

    4. Missing avatar

      virginia DeBenedictis on

      What you are doing is truly a pioneering effort and what you have accomplished is amazing. We do not know all the impacts of pioneering endeavors--it is the nature of the entity. But no one could have put forth more effort in this undertaking. Kudos to you and your team and Skycube's supporters. Ad astra per aspera.

    5. Tim DeBenedictis Creator on

      Keith - I certainly didn't mean to give the impression we're relying on amateur radio operators to find the satellite. Rather, one of our project goals was to provide tools for amateurs to detect transmissions from the satellite. We're doing that now. As far as the other things you suggest - yes, we're doing all of that, too, right now.

    6. Missing avatar

      Keith Nealy on

      Seems odd that you can't find it. I thought the government tracked all orbital objects. If they know where all five are, but don't know which is which, and they're separated by thousands of miles, why can't you look for your signal at each pass for each of them? Does it not send an ID as part of its telemetry? Can you ping it? I thought you had ground stations that would send you info. No? It's up to ham operators?