Satgen 520  Iridium and Hubble  by GM4IHJ   (BID SGEN520)  1999-03-13

Iridium Mobile Phone satellites. 
Recent frequencies and times of day heard, are :-

Please note that doppler shift on these frequencies can be quite large
so the signal may appear anywhere within 40 kHz of the frequency noted
here. Sats appear roughly 9 minutes apart but there can be gaps with
nothing heard . Signal times one day repeat 3 minutes later next day.

1626.310 MHz sets of clicks , new sat roughly every 9 minutes, between
             2200 to 1100 local time.
1626.250 MHz same type of signal 1100 to late pm local time

A totally different kind of signal which sounds like continous bursts
of a stick being rubbed along a wooden fence , and which may be,
complete blocks of time division multiplex digitised voice calls, can
be heard as follows, on southerly headings.

1625.557 to 1625.500 MHz in the morning
1625.502 to 1625.493 MHz afternoon and evening passes.
1625.175 to 1625.164 MHz afternoon and evening passes with the passes
around noon being descending north to south orbits heard as they go
down to the IHJ southern horizon, noting that the IHJ antenna is fixed
on a southerly azimuth. FFT DSP fingerprints of these signals show a
minimum of 3 carriers /sub carriers , spaced about 200 Hz apart.

Other frequencies are undoubtedly in use , but listening at IHJ has
concentrated on those listed here, in an effort to understand the
basic operating pattern. Right Ascension changes and thus orbit
patterns/timings, get slighly earlier each week, noting that Iridium
orbits are not sun synchronous.

Hubble Space Telescope.

As anticipated in the report in Satgen 505 of November last. Hubble
has had another stabilising gyro failure. The Space Telescope has 6 of
these units , 3 in use, 3 spare. But it has now lost 3 of them as the
unit which was erratic in November has now had to be shut down,
joining the two previous failures. 

Another failure would require Hubble to be shut down , into safe mode,
rendering it totally non operational until repairs could be effected.
The next scheduled repair / refit mission is not programmed until June
2000. So NASA is worried that the telescope may not remain operational
until then, In consequence of which NASA is considering a possible
emergency repair mission in October 1999.

A decision on this is expected in the next two weeks, noting that, the
schedule of Space Shuttle flights for the remainder of 1999, will have
to be altered anyway, consequent on the possibly delayed delivery of
the Russian Service module to the International Space Station. This
delivery was planned for September 99 , but may now be delayed until
November or later.