Tuesday May 19th 2009. Day 5.
Today has been a
good day for Herschel. As announced yesterday, our first instrument was
switched-on. A successful SPIRE switch-on happened at
11:39UT. Data was received all afternoon as SPIRE scientists gave the
instrument a careful check-out. Our first instrument is on and functioning.
Tomorrow the SPIRE team will continue running through their tests, in
preparation for the first trial observations on Friday. The SPIRE team is
rightly jubilant and say that everything is worked just as it did in ground
testing. To operate SPIRE the team went to Mission Control in
Meanwhile, preparations continue for the first science observations
with Herschel in the autumn. Hundreds of observations need to be updated now
that changes have been made in the configuration of the instruments as a result
of the tests made through the autumn and winter. Many parameters have been
measured and checked and all kinds of fine-tuning made to get the best out of
the three instruments. This operation will continue in space as, when we start
to look at stars, it is inevitable that new information will come to light that
makes us change further the way that observations are made: it is all part and
parcel of operating in space.
Today we have had a silly season story. Apart from the four main
pieces flying together in space (Herschel, Planck, the Sylda and the Ariane
upper stage), the Minor Planet Center is tracking two other, unexplained
objects near to the Ariane. However, deep images have revealed a series of
other, faint unconfirmed objects. These have been widely discussed on the
Internet with comments ranging from them being evidence that alien spacecraft
were pursuing Herschel, to hysterical suggestions that something had broken off
Herschel (this last suggestion totally ignoring the fact that all the telemetry
from Herschel shows that it is in excellent shape). By one count there are as
many as 14 additional objects tracking Herschel and Planck. What could they be?
We have discussed this widely over the last couple of days. As far
as we can work out, there are two probable explanations. It is quite likely
that some of the faint blobs are due to the covers of the thrusters on the
Ariane upper stage. However, the most likely explanation for most of them is
that they are pieces of ice that shook off the upper stage around separation.
Some of the ice would have stayed in shadow for much of the ascent, finally
breaking off as it warmed. Fresh ice has an albedo of up to 90%, meaning that
even rather small pieces could be quite bright. Explaining all this has kept us
entertained for a couple of days and led to a lot of brainstorming. Maybe
though we are wrong and need to add Mr. Spock to the picture below!
http://www.observadores-cometas.com/Herschel/Image_of_the_day/image_of_the_day.htm
Frequent updates are provided during the day on the Herschel Twitter (ESAHerschel) here: