TopBand: Fwd: BULLETIN: Scientists lose contact with the SOHO Spacecraft
KE1YRolf@aol.com
KE1YRolf@aol.com
Fri, 26 Jun 1998 21:57:58 EDT
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Hi friends,
I thought you might be interested in these news.
By the way, they are the group who has the "real time grey-line" web site for
low band dx-ing.
73, have a good weekend.
Rolf, KE1Y
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From: Cary Oler <oler@holly.cc.uleth.ca>
Message-Id: <199806270027.SAA12879@holly.cc.uleth.ca>
Subject: BULLETIN: Scientists lose contact with the SOHO Spacecraft
To: KE1YROLF@AOL.COM
Date: Fri, 26 Jun 1998 18:27:07 -0600 (MDT)
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We are issuing the following bulletin as it could have a considerable impact
on
space weather operations and forecasting.
Loss of Contact with the SOHO spacecraft
(adapted from SOHO-News)
26 June 1998. At 01:16 Paris time on 25 June 1998 (23:16 GMT 24 June),
during routine maintenance operations, ground controllers lost contact with
the SOHO (Solar and Heliosopheric Observatory) spacecraft and the satellite
went into Emergency Sun Reacquisition (ESR) mode. The ESR mode is activated
when an anomaly occurs and the spacecraft loses its orientation towards the
Sun. When this happens, the spacecraft automatically tries to point itself
towards the Sun again by firing its attitude control thrusters under the
guidance of an onboard Sun sensor.
Efforts to re-establish nominal operations did not succeed and telemetry was
lost. Subsequent attempts using the full NASA Deep Space Network
capabilities have so far been unsuccessful.
ESA and NASA engineers are continuing with the task of re-establishing
contact with the spacecraft.
The SOHO mission is a joint undertaking of ESA and NASA. The spacecraft was
launched aboard an Atlas II rocket from Florida on 2 December 1995 from the
Cape Canaveral Air Station. Mission operations are directed from the control
center at NASA Goddard Space Flight Center in Maryland, USA.
In April 1998 SOHO successfully completed its nominal two-year mission to
study the Sun's atmosphere, surface and interior. Major science highlights
include:
* the detection of rivers of plasma beneath the surface of the Sun;
* the discovery of a magnetic 'carpet' on the solar surface that seems
to account for a substantial part of the energy that is needed to cause
the very high temperatures of the corona, the Sun's outermost layer;
* the first detection of flare-induced solar quakes;
* the discovery of more than 50 sungrazing comets;
* the most detailed view to date of the solar atmosphere;
* spectacular images and movies of Coronal Mass Ejections, which are
being used to improve the ability to forecast space weather.
---------- End ----------
STD:
The (hopefully temporary) loss of contact with this spacecraft could have a
considerable impact on space weather forecasting. Until now, space weather
forecasters have relied very heavily on the suite of instruments available
from
SOHO to determine where solar energetic events such as solar flares occurred
on
the Sun when ground-based observations were not possible. They also relied on
this spacecraft very heavily to help determine whether coronal mass ejections
from the Sun were Earth-directed. The loss of acquisition with this spacecraft
could mean forecasters might have to resort to much less accurate methods of
determining whether coronal mass ejections occurred. The accuracy of
forecasts
is likely to drop correspondingly unless the spacecraft can be reacquired.
** End of Bulletin **
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