Prospero (X3)

Prospero X3The Prospero satellite, also known as X-3, is a satellite launched by the United Kingdom in 1971. It was designed to undertake a series of experiments studying the effects of the space environment. It is the only United Kingdom satellite to be successfully launched by a UK rocket; it was launched in October 1971, remained operational until 1973, and was contacted annually for over a quarter century after that. At 0409 GMT on October 28, 1971, the fourth and final Black Arrow left its launch pad at Woomera and placed the Prospero satellite (International designation: 1971-093-A) into an orbit inclined at 82 degrees to the equator about 10 minutes after liftoff. The initial orbit had a perigee (low point) of 537 kilometres and an apogee (high point) of 1,593 kilometres. (As of 12 April, 2007, Prospero’s orbit was 531 by 1,330 kilometres and the satellite had completed about 77,400 orbits.)

Orbital parameters

Name                 PROSPERO
NORAD                05590
COSPAR designation   1971-093A
Inclination (degree) 82.044
RAAN                 242.312
Eccentricity         0.0543105
ARGP                 245.422
Orbit per day        13.90384562
Period               1h 43m 34s (103.57 min)
Semi-major axis      7305km
Perigee x apogee     531 x 1402
Drag factor          0.000397620 1/ER
Mean anomaly         108.945


137.560 MHz 300mW PM, 2048 bit/s PCM
148.000 MHz (unknown)


TLE (october 19, 2011)

1 05580U 71093A   11291.61144574 +.00002376 +00000-0 +56163-3 0 09176
2 05580 082.0410 258.8711 0544021 299.6964 055.1125 13.90307377003077


A pdf document original written by H.J.H. Sketch: click to read

Original Ground Station

Prospero Ground Station

Original Ground Station Antennas

Prospero Ground Station Antennas

Black Arrow RocketAnniversary / re-contact

A team in the UK are trying to re-contact an old British launched satellite for the anniversary of its launch (28th October 1971).

We’ve been given a licence to transmit and will be testing our  re-engineered ground-segment in the next fortnight. The passes we are going to concentrate on will be as far out west as possible, as to minimise QRM from Europe.

Earth is a lot more EM noisy than it was in 1971. If anyone in the UK wants to try and tune in to the downlink, you can help ID any response we get from the old bird.

The passes are summarised here: passes There are other passes, though these are the ones which are out west. We’ll see how we do. (Time is in BST (UTC+1))

Date      Mag  Starts                Max altitude            Ends
               Time         Alt. Az. Time          Alt. Az.  Time         Alt. Az.
10/19/11  7.9  05:44:20 PM  10   SW  05:50:23 PM   48   WNW  05:57:37 PM  10   N
10/20/11  8.3  05:55:41 PM  10   SW  06:01:40 PM   38   WNW  06:08:40 PM  10   N
10/21/11  8.7  06:07:13 PM  10   WSW 06:13:01 PM   31   WNW  06:19:40 PM  10   N
10/22/11  8.9  06:18:55 PM  10   WSW 06:24:26 PM   25   NW   06:30:37 PM  10   N
10/23/11  9.2  06:30:49 PM  10   W   06:35:55 PM   21   NW   06:41:29 PM  10   N
10/24/11  7.7  04:54:19 PM  10   SSW 05:00:56 PM   58   WNW  05:08:42 PM  10   N
10/25/11  8.1  05:05:35 PM  10   SW  05:12:10 PM   47   WNW  05:19:45 PM  10   N
10/26/11  8.4  05:16:59 PM  10   SW  05:23:27 PM   38   WNW  05:30:45 PM  10   N
10/27/11  8.7  05:28:35 PM  10   WSW 05:34:49 PM   31   WNW  05:41:43 PM  10   N
10/28/11  7.4  03:53:22 PM  10   S   04:00:25 PM   86   W    04:08:32 PM  10   N

Source: amsat-bb

Documentary about the British space program (including prospero information)

Signals I have recorded:

The last days I’ve listened to several passages of Prospero. Below I have posted some data from a passage on Friday 21th October. I have no idea what to listen for. But if I compare these sounds to what was heard in the first episode of the second series of BBC’s Coast, then it matches.

October 21, 2011 – 19:07 CEST

A mp3 file of the pass on Friday 21th October 19:07 CEST 137.560 MHz:

This is the spectrum from that file:

Prospero Spectrum 21-10-2011

The signals I receive on 137.560 MHz are also there before AOS and after LOS, but when you look at the video from BBC Coast the person with the antenna, says at one point that he receives signals from the satellite, and that sound is the same as what I hear. An old audio fragment would be useful.

There is a possible explanation for the signals that I receive and can be seen in the spectrogram. This are probably signals that are transmitted by ORBCOMM. The 57k6 broadcasts of the ORBCOMM satellites. The frequency 137.560 was received by the ORBCOMM organisation after Prospero was no longer active on that frequentie.

October 24, 2011 – 17:55 CEST

I have read that prosperso can transmit on two frequencies. The other frequency is 148.000 MHz and is as far as I can find, this frequency is assigned to command mode. Here is a spectrum of the data I received on that frequency.

A mp3 file of the pass on Monday 24th October 17:55 CEST 148.000 MHz:

Prospero Spectogram 24-10-2011 17:55CEST

Homepage and other references:

Prospero X-3 wiki page
UCL Blog