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Re: EROS Rendezvous: NEAR Mission Problems- spacecraft *DID NOT* explode



On Mon, 21 Dec 1998, Dr Thomas A Clark (W3IWI) wrote:

> Last night, the NEAR mission to rendezvous with the asteroid EROS
> was scheduled to have a final 20 minute burn of the bi-propellant
> motor to put the spacecraft into EROS orbit. The following note
> appears on the NEAR project web site at URL 
>        http://near.jhuapl.edu/ 
> 
> > NEAR Rendezvous Burn Aborted 
> > 
> >    The first rendezvous burn of the NEAR spacecraft's bipropellant 
> >    engine, scheduled for Dec. 20, at 5 p.m. EST, was not completed 
> >    as planned. Except for brief communication shortly after the 
> >    scheduled 20-minute burn period, contact with the spacecraft 
> >    has been lost. Mission Operations is now working to reestablish 
> >    contact based on expectations that NEAR has entered safe mode 
> >    after the burn was aborted by the spacecraft. 
> 
> The story I hear is that communications were abruptly lost after ~2 
> seconds of the planned 20 minute motor burn. The last weekly status
> report on 18 Dec gives no hints of any problems, as seen in 
> 
>    http://near.jhuapl.edu/Reports/WeeklyStatus/1998-12-18.txt 
> 
> Some of my colleagues here at GSFC who were involved when a similar 
> incident killed the Mars mission a few years ago are expressing a 
> strange feeling of deja vu.
> 
> 73, Tom


Our spy at Johns Hopkins APL informs us that they have a weak radio
signal from NEAR, the spacecraft did not explode. It is pointing its
solar arrays at the sun but the high gain antenna is not pointing at
the Earth, so they are limited to an omni antenna for telemetry. 
There is still time to do the Eros rendezvous burn, if they can 
determine what caused the engine to shut down the first time.

Meanwhile, we have heard via the grapevine that SOHO is in safemode 
once again, having lost the one remaining gyro that was not damaged
in the incident last summer. They can control the spacecraft without
gyros, using only the star tracker, but they will need to write and
uplink new software to accomplish that.

Dan Schultz N8FGV  
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