Nervous waiting time for X-ray astronomers

It’s again the week before Wimbledon. For an X-ray astronomer,
it means the days when a large review panel meets in Boston
and allocates next year’s observations on the Chandra
X-ray Observatory, one of the best X-ray telescope available
to the astronomical community. Personal pride and research
opportunities are at stake, and pretty much out of
our hands by now.

The Chandra X-ray Observatory

Every year, the build-up to this week begins in late February,
when we start scratching our heads or emailing colleagues,
thinking of possible projects that might be interesting
enough to deserve the use of the Chandra telescope.
A typical research proposal would ask for somewhere between
half a day and three days of Chandra time. Everybody can apply,
provided that they can write up a compelling science case,
explaining why they want to use this $2bn, 25-tonne
instrument, and exactly for how many seconds. A research
proposal consists of a four-page scientific plan (for
example, explaining expected results or theoretical
predictions) plus some technical details about the observational
setup. By the strictly-enforced deadline on March 15,
some 800 proposals would have been submitted online
to the Chandra X-ray Center at Harvard (the body responsible
for collecting proposals and for selecting the review panel).
Only about 150 of them each year can be successful. This means
that the chance for a proposal to be allocated time on Chandra
this time around is slightly less than the chance to win
a Centre court ticket for Wimbledon through the public ballot.
Unlike the All England club, the Chandra X-ray Center accepts
more than one proposal per scientist.

At the beginning of April, about 100 astronomers
representing a cross-section of nations and universities
are selected, on a voluntary basis or after getting their
arms twisted, to assess the proposals. Each panelist will
have to read, grade and write a short report for up
to 80 proposals: a task that may take almost a month
of committed work (very few of them will put their hands
up again next year). In the end, the reviewers convene
in June to compare their marks, write the final reports
and select the winning proposals. The 3-day meeting
takes place always at the Hilton Hotel at Boston-Logan
airport. Not the most exciting holiday destination. But
at least this year the panelists will have the chance
to watch and enjoy the Celtics’ victory parade in downtown
Boston–their first NBA title since the last time Halley’s
comet was around.

And then, a patient wait until the first week of July,
when the results will be made public, and the grades
of selected and rejected proposals will be emailed
to the hopeful proposers. For the lucky ones,
the data will be taken sometime next year.
Successful US proposers have an added bonus: about $1
for every second of observing time in their proposal,
which can be worth more than a year’s salary.
For the unlucky proposers, there’s always a chance
to try again next year. When a British player will
finally win the Championships.

Cassini’s mission continues

One of the major missions that MSSL is involved in is Cassini-Huygens: a NASA/ESA/ASI mission to Saturn and its moons. After almost 4 years looping arund the planet and gathering a immensely valuable set of data, it’s been announced that the mission will be extended to 2010. Some of the mission’s highlights so far include the landing of the European Huygens probe on the surface of Titan, Saturn’s largest moon, the discovery of geysers of water vapour and ice grains emanating from the moon Enceladus’s south pole, an atmosphere surrounding Saturn’s rings, and the possible detection of a disk of debris or rings around the second-largest moon, Rhea.

MSSL’s contribution is the Cassini Plasma Spectrometer’s Electron Spectrometer, or CAPS-ELS. This instrument senses the electrons in Cassini’s vicinity, helping build up our understanding of Saturn’s magnetosphere – a huge bubble of charged gas that surrounds the planet, and how it interacts with the planet’s moons and rings.

Titan’s upper atmosphere from Cassini (NASA/JPL/SSI)

ELS is also telling us some very unexpected things: a major surprise of the mission has been at Titan. During several flybys of this moon, ELS has recorded very strange signatures. The only particles that fit these signatures aren’t electrons at all, but negative ions. The vast majority of atoms and molecules in Titan’s upper atmosphere have a positive electrical charge, but ELS has shown that there are lots of negative ions there too, providing a key piece of information for understanding the complex chemistry that goes on there.

Cassini’s mission extension, beginning on July 1, will include 21 Titan flybys, 7 Enceladus flybys, and several flybys of other moons including Mimas, Tethys, Dione, Rhea, and tiny Helene. The Planetary Society have compiled a handy list of key events during the prime and extended missions.

Some of the biggest results to come from Cassini so far include many unexpected discoveries, coming from instruments that weren’t designed to observe what they’ve found: as well as ELS’s discovery of negative ions, Enceladus’s south polar plume was first sensed by the magnetometer, and Rhea’s suspected ring system wasn’t found by a camera, but by the suite of magnetospheric instruments. The chances are high that there will be more surprises in store over the coming two years…

Staring at the Sun

There is currently lots of research activity at the lab based around a Japanese mission called Hinode. We led the development of one of the telescopes on the spacecraft so are heavily involved on a day-to-day basis. Last week we had 2 visitors over from Hinode headquarters so that we could work together and look in detail at the vast magnetic structure that the Sun has in its atmosphere. We saw some amazing things!

3… 2… 1…

We have liftoff of the MSSL blog, on its mission to inform, educate, and maybe occasionally entertain!