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Miscellaneous Tracking

Tyneside, UK
2024 Jul 24
Wednesday, Day 206

Curated by:

Cosmos 2463 - Broken?

2010 August - Sven Grahn was monitoring the Swedish Prisma satellite pair transmitting at 400.550 MHz when he noticed a CW transmission at 400.530 MHz that exhibited a classic satellite Doppler curve.

The first challenge was to identify it because the frequency had no history. Further observations from the UK tied down the orbital period to 104-106 minutes and showed that it was in a polar orbit. It was something of a surprise when Ted Molczan analysed the observation timings and identified it as Cosmos 2463, a Russian Parus satellite.

400.530 MHz is not a known Parus transmission frequency. The first thought was that it might be a secondary payload but this did not seem likely.

Standard Parus Behaviour

Cosmos 2463 has a transmission at 149.940 MHz carrying almanac and time data. There is a CW signal at 399.840 MHz to aid Doppler-based tracking. They are standard Parus frequencies and are coherent in the ratio 8:3.

Further Developments at 400 MHz

A few days later, while monitoring the standard 400 MHz Parus frequencies from the Zarya location, a CW transmission at 399.977 MHz was logged. There was a further surprise when it too was traced to Cosmos 2463. Suspicion began to grow that there might be a problem with Cosmos 2463's transmission system. It was reinforced when two further frequencies, 399.150 MHz and 399.703 MHz, yielded signals.

400.530 MHz and 399.150 MHz are respectively 690 kHz above and below the 399.840 MHz operational frequency. Similarly the 399.977/399.703 MHz pair is at ±137 kHz.

2010 Late September, while monitoring another satellite, a stray transmission from Cosmos 2463 was logged at 400.117 MHz.

150 MHz - Problems Here Too

Cosmos 2463's almanac/time data transmission at 149.940 MHz also exhibits 'images' at other frequencies. The data transmission is repeated at 150.215 MHz and 149.665 MHz, symmetrically arranged 275 kHz above and below 149.940 MHz.

Possible Root of the Problem

The answer might simply be "age". Parus is in its declining years and Cosmos 2463 is from a limited stock of spare vehicles manufactured several years ago when the system was in its heyday.

Being in store for a time will have taken its toll, however good the storage conditions. Even if the satellite passed all tests prior to launch, minor deterioraion of components might have compromised its ability to withstand the ride to orbit and exposure to space.

The question is open as to whether the 'extra' transmissions were present immediately after launch 2010 April 27, or arrived sometime later. There is no unusual activity logged against Cosmos 2463 prior to August but, with so few radio observers, it is not surprising that it might have been missed.

Cosmos 2463 Frequency List

These are the frequencies that have been discovered. Other images might exist in pairs near both 400 MHz and 150 MHz - as detected at 400.171 MHz 2010 late-September. Any reports would be appreciated.

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Freq (MHz) Satellite Mission Signal Type Notes