- As predicted, SOHO has stopped sending back data for the time being.
There's good news and bad news. First the good news. Sunspots can
still be seen and cataloged using ground-based obervatories. That's
how it was done, anyway. The GOES-12 satellite soft x-ray imager can
be used to find coronal holes. While they don't stand out as well as
in the SOHO UV light imagery, they are detectable. Flares can be
detected from a few different satellites, so that's not a problem.
Now for the bad news. For the purposes of space weather forecasting,
by far the biggest impact is the loss of SOHO's LASCO coronagraph
imagery. That images from that instrument provided a three day
warning if a CME was headed out way. While the TRACE satellite and
analysis of solar output in the radio freqencies can detect of a CME
has been launched, there's nothing that can tell exactly what
direction it's headed in. If a CME is Earth-directed, we won't be
able to tell until it arrives at the ACE (Advanced Composition
Explorer) satellite, which is the one that provides the solar wind
data. At best, we would have about a 1 hour warning. One hour
instead of three days is a big loss. The loss of the UV images will
have a big impact on the scientific community, but not so much on
space weather forecasting.
If it's any consolation, SOHO will be back in a position to start
returning data again in a little over two weeks. Unless the engineers
can figure out a fix, 18 days of outage every three months will be the
pattern we have to live for the forseable future.