Forward: ESA press release on SOHO

rkresken@esoc.esa.de
Fri, 26 Jun 1998 12:49:49 +0100

  SOHO spacecraft observations interrupted

  At  01:16  Paris  time  on  25  June  1998,  during   routine mainten=
ance

  operations,  ground  controllers  lost contact with  the  SOHO (Solar=
 and

  Heliospheric   Observatory)  spacecraft  and  the  satellite   went  =
into

  Emergency Sun Reacquisition (ESR) mode. The ESR mode is activated whe=
n an

  anomaly occurs and the spacecraft looses its orientation towards the =
Sun.

  When  this  happens,  the  spacecraft automatically tries to point it=
self

  towards  the Sun again by firing its attitude control thrusters under=
 the

  guidance of an on board Sun sensor.



  Efforts  to re-establish nominal operations did not succeed and telem=
etry

  was  lost.  Subsequent  attempts  using  the full NASA Deep Space Net=
work

  capabilities have so far not been successful.



  ESA  and  NASA  engineers are continuing with the task of re-establis=
hing

  contact with the spacecraft.



  The  SOHO  mission is a joint undertaking of ESA and NASA. The spacec=
raft

  was  launched  aboard  an Atlas II rocket from Florida on 2 December =
1995

  from  the  Cape  Canaveral  Air Station.  Mission operations are dire=
cted

  from  the control center at NASA Goddard Space Flight Center in Maryl=
and,

  USA.



  In  April  1998  SOHO successfully completed its nominal two-year mis=
sion

  to  study  the  Sun?s  atmosphere,  surface  and  interior. Major sci=
ence

  highlights  include the detection of rivers of plasma beneath the sur=
face

  of  the  sun;  the  discovery of a magnetic ?carpet? on the solar sur=
face

  that seems to account for a substantial part of the energy that is ne=
eded

  to  cause  the  very high temperatures of the corona, the Sun?s outer=
most

  layer;  the  first detection of flare-induced solar quakes; the disco=
very

  of  more than 50 sungrazing comets; the most detailed view to date of=
 the

  solar  atmosphere;  and  spectacular  images  and  movies of Coronal =
Mass

  Ejections,  which are being used to improve the ability to forecast s=
pace

  weather.





  For further information:



  Franco Bonacina, ESA,  Paris (Phone: + 33 1 5369 7713)

  Don Savage, NASA Headquarters, Washington DC (Phone + 1 202 358 1727)=


  Bill  Steigerwald, Goddard Space Flight Center, Greenbelt, Md. (Phone=
 + 1

  301 286 5017)



  SOHO homepage: http://sohowww.nascom.nasa.gov/
=