🚀 go-pugleaf

     On Mar. 29th the Soviet Union's Phobos II probe suffered a fatal 
failure.  On Mar. 21st it had undergone the final maneuver, placing it in 
synchronous orbit with the Martian moon.  On Mar. 26th pictures of Phobos 
had been taken from about 150 Km (94 mi) from away. On the 27/28th a second 
close up set was being taken.  This was to generate the final orbital 
measurements to insure the close approach could be done about 1 week later.  
On the Phobos probes the antenna system is not mounted on its own transport 
platform (as is done on most US probes).  Instead the vehicle was commanded 
to turn away, take the pictures, then return contact to Earth control.  
However, in this case the probe rotated away, but never came back.  
Compounding the problem of regaining command was the fact that it had 
previously lost its main transponder, a 50 Watt system, and was now 
operating on this 5 Watt backup.  Thus there are two main probable failure 
points, the first being that the control system broke down thus leaving the 
probe unable to get back to Earth alignment.  The other possibility is that 
the transmitter died, and there was no backup left.  Electronic equipment 
often fails just when it is turned on again, as would be the case with this 
observation method (the 30 Megabit memory could hold 1100 picture sets so 
there was no need to transmit these in real time).  It is not obvious which 
problem occurred here though some reports say that faint signals were 
received from Phobos II after this failure.  The NY Times quotes Nikotal 
Simyonov as saying "it would be very difficult at this point to get a 
response form the spacecraft".  The more time the craft is without earth 
command the more likely it will loss the sun alignment for its solar cells, 
thus suffering a power deficit also.
    Note that the mission was not a complete failure.  Even with the data 
obtained at this point the probe has produced the "the highest quality 
images of yet obtained of Phobos".  In addition at Mars itself the infrared 
spectra give much compositionial information about the planet's surface and 
atmosphere, while the planetary magnetic field has been measured.  Never 
the less there is bitter loss at missing the Phobos landing by only a few 
days. (Boston Globe and New York Times, Mar. 30)
    One comment here, the researchers at the Soviet IKI institute, which 
were in charge of the probe, have been pushing the line that unmanned 
systems are cheaper and more reliable than manned ones.  They have been 
strongly suggesting that robots would be better to explore Mars rather than 
a manned mission.  After this high profile mission failure they could find 
their case substantially harder to present in the USSR.
    [Personal note - why is it that things only go really wrong with the 
Russian program when I am off on a trip, and hence without my shortwave.  
At one earlier conference the Soyuz TM-6 re-entry problem occurred.  Sorry 
for the delay in posting this but I just got back.]
    So the Russians failed in this attempt on Mars.  It was a loss to us
all (no US probe for Phobos is scheduled yet, and probably would not occur 
before 2000 AD).  It will be interesting to see if they launch a second try 
in the 1990 or 1992 windows, if they can analyze the failure cause.

                                                  Glenn Chapman
                                                  MIT Lincoln Lab