UNITEC-1: A New Deep Space Adventure

[alexc]

Greetings,

We can look forward to new exciting opportunities for playing with deep space communications at microwave frequencies.

If everything goes according to current plans, JAXA will launch their PLANET-C spacecraft towards Venus on May 18, 2010. To fill out the empty space and available payload mass on the H-IIA rocket, they will also bring four university built cubesats into orbit. One of these cubesats, UNITEC-1, is very special in that it will follow PLANET-C all the way to Venus, although without any propulsive capabilities to make trajectory corrections it might end up somewhere else – we'll see about that. Another special thing about UNITEC-1 is that it will be using the 6 cm amateur radio band. Cubesats have a tendency to be stuck on VHF and UHF frequencies for understandable reasons, so a 5.8 GHz signal from deep space will be an interesting challenge!

We at AMSAT Denmark are currently working on a C-band receiver setup based on our existing 7m dish, GNU Radio and the Universal Software Radio Peripheral:



This time our objectives go far beyond just having some fun tracking a spacecraft:

• Receive telemetry from an interplanetary spacecraft. UNITEC-1 will transmit telemetry on 5.84 GHz using very simple ON/OFF keying at 1 bit per second. This is quite exciting – I believe it will be the first time that we can receive unencrypted telemetry from an interplanetary spacecraft.
• Support the UNITEC-1 operators by tracking their craft. By providing them with accurate measurements of antenna pointing and Doppler shift, the operators can estimate the actual trajectory of the craft (remember, UNITEC-1 does not have any coherent tracking transponder on-board). More tracking data from around the world will improve their statistics significantly.

You can find a work-in-progress page about the setup here - it will eventually become a complete description.

So far the progress has been good, we have acquired and tested the LNC and there is also good progress on the software side.

We expect to mount the feed and the LNC on the dish with a few weeks so that we can test the receiver during the European EME contest on 5.7 GHz on April 24-25.



I will post significant updates here. Feel free to ask if you have any questions.

[scasey]

Great - I look forward to hearing more about this!

SC

[tristancho]

Oh!
Good news.
Press on.
Joshua

[alexc]

Tuesday this week, we have successfully tested the receiver chain (as shown on the diagram above less the 7m dish) on the air using a 5.8 GHz beacon signal coming from ~50 km distance: http://www.youtube.com/watch?v=6UToyq7yptg

[tristancho]

Congratulations!
Is this IKEA red dish yours?
Best,
Joshua Tristancho

[alexc]

No, the IKEA dish belongs to the club. As far as I know IKEA does not have them anymore
... but now you know what to look for whenever you walk by a lamp shop. It can be a very cheap dish if you find a lamp with a suitable f/d ratio.

[alexc]

The launch of UNITEC-1 is getting closer (17. May) and we are almost ready.
I have posted updated information about the receiver hardware.
.

[alexc]

A few quick updates...

Link budget for UNITEC-1 indicates there will be good margin in the beginning to track using a small dish. This is very good because the trajectory predictions are very uncertain and having a wide beam width will make it easier to find it. Remember, it's a free launch and JAXA will only provide reliable state vectors for the primary payload, PLANET-C. If we can't find UNITEC-1 within the first few days we might completely loose it

There is a tool for generating trajectory data based on ECI [t,X,Y,Z,Vx,Vy,Vz] state vectors, available here - see video demo. Very easy to use.

It looks like we will have tracking windows between 17:00 and 00:00 UTC. I will try to set up live video feed from our control room but as it is now I need an extra computer for that so it is rather uncertain. If I can make it happen it will be avaialble on this Ustream channel.

I have also uploaded a video of our 7m dish, but we will probably use the small IKEA dish to begin with.

Live broadcast of the launch will be available from JAXA.

[tristancho]

Oh, so exciting!
Best,
Joshua Tristancho
(Team FREDNET)

[alexc]

Launch today got scrubbed due to bad weather but there will be a window every day for a month or so...

We decided to use a small 90cm dish in for the first days after launch in order to have a wider beam width. Unfortunately, the Azimuth rotator was broken so we had to fix it few hours before launch time.

The Azimuth rotator is the thing right below the horizontal mast so we had to choose between disassembling or lifting the whole construction (very heavy). We chose to lift it...

Still, repairs took a bit longer than expected...


Much longer...


I also took a photo of our 7m dish in daylight

[tristancho]

So huge! great.
Best,
Joshua

[alexc]

So huge! great.
Best,
Joshua

It's only 7 meters

Tuesday evening we fixed the 180° offset on the Azimuth rotator, made a 5.8 GHz helical feed for the 90cm dish and tested it using OZ7IGY beacon 40km away. You can click on photos to get them in higher resolution.

The helical feed:




Peter Scott, OZ2ABA, mounting the helical feed and LN on the dish - yes, that's the moon in the background


The helical feed and LNC mounted on the dish:


Testing the 90cm dish, 5.84 GHz helical feed and Kuhne LNC using GNU Radio and USRP:


I have also recorded a video, you can watch it on YouTube:
http://www.youtube.com/watch?v=VP8y7DJE8k0

[alexc]

UNITEC-1 has been successfully launched and separated on May 20, 21:58:22 UTC, but unfortunately it appears that the spacecraft has been lost already during the first mission day despite the coordinated efforts between Japanese and European teams. Japanese ground stations were able to receive both the orbit determination downlink and the major/minor data downlink during the first pass after launch; however, the signal has been lost during the first mission day sometime between LOS over Japan and AOS over Europe.
You can read more details in my UNITEC-1 Tracking Report.

[tristancho]

Wow, something could be wrong in anytime; this is a lesson to learn.
Best,
Joshua

[scasey]

The launch is the one aspect of the mission that you have no control over. The only mitigation is insurance and having a second/third payload.

Great photos Alex!

Are there plans for a follow-up attempt?

What about using the ground facilities for other missions?

SC

[tristancho]

Oh yeah,
This is because the space sector is so expensive: insurances.
My best,
Joshua

[scasey]

The insurance is to mitigate risk not cost.

SC

[alexc]

Are there plans for a follow-up attempt?

We did not try since then. Under normal circumstances I would have taken the time to just sit and listen during those 6 hours per day but I am in a very busy period at work, so it is difficult to find the time.

The Japanese ground stations kept trying but so far I heard no news that they have received anything.

At this point it is rather unlikely that anyone will hear it again. Even if it starts transmitting again the trajectory has diverged a lot from PLANET-C and IKAROS so we don't know where to look exactly. This is a problem because at this point very large antennas are needed and they have very narrow beam width - even our 7m dish has a beam width of 0.5 degrees at 5.8 GHz.

What about using the ground facilities for other missions?

The OZ7SAT facilities are used routinely for monitoring amateur radio satellites. This happens autonomously according to predefined schedule with minimal surveillance and maintenance. The collected data becomes available on the net shortly after each pass at http://www.amsat.dk/oz7sat/index.php (top-right: Telemetridata) and the community is very pleased with this free service.

We are slowly upgrading the station to cover more frequencies. Now we have all amateur radio frequencies up to 2.4 GHz + 5.6-5.9 GHz with the recent upgrade. We are also planning to add 2.2 GHz and maybe 8.4 GHz downlinks. We are not sure how good the 7m dish will be at 8.4 GHz since it is a mesh dish and it will certainly also require doing some work on the hydraulic drive to enhance the pointing accuracy.