Results tagged “Herschel”


Funding for space missions in the UK was split from the Science and Technology Facilities Council to the the UK Space Agency earlier this year. Very roughly, UKSA will fund the missions themselves all the way through to the processing of data, while STFC will fund the science that comes from analysing the data.

To try to be a little more specific, the agencies have put out a press release on this so-called “dual key” approach: “Who does what? — Arrangements for sharing responsibility for the science programme between the STFC and the UK Space Agency.” The executive summary is:

  • UKSA

    • ESA subscriptions
    • Mission-specific instruments
    • Operation of UK instruments (Post-launch support)
    • Aurora integrated national programme
  • STFC:

    • Early R&D for space science (non-mission specific)
    • Studentships/fellowships
    • Scientific exploitation of missions

This still leaves many of the details of the split unanswered, or at least fuzzy: How do we ensure that government supports the two agencies adequately and jointly? How do we ensure that STFC supports science exploitation from missions that UKSA funds, so that the UK gets the full return on its investment? How do we define the split between “data analysis” and “science exploitation”?

Here at Imperial, we work on both sides of that divide for both Planck and Herschel: we are the home to data analysis centres for both missions, and want to take advantage of the resulting science opportunities. Indeed, as we take the Planck mission ahead towards its first cosmology results at the end of next year, we are already seeing some of these tensions played out, in both the decision-making process of each agency separately as well as in the overall level of funding available in these austere times.

Results from the first major science papers from the Herschel Satellite were released this week at a conference in Holland. Launched almost a year ago on the same rocket as Planck, Herschel is an infrared and sub-millimeter telescope, which lets it see not only the stars that generate the visible light we see with our eyes and ordinary cameras, but also the gas and dust that absorb and re-radiate that light. That gas and dust carries information about both the birth and death of stars: the detritus of exploding stars pollutes the interstellar medium, which eventually condenses out to form new generations of stars. On larger scales, Herschel’s observations let us trace the evolution of entire galaxies, the most important tracers of large-scale structure, formed from seeds laid down somehow in the first instants of the Universe (and, bringing it all back to cosmology, which are viewed by Planck in a much earlier form).

My Imperial colleagues and Herschel scientists Dave Clements and Brian O’Halloran discuss the results in much more detail over on the Herschel mission blog,  or you can keep more up to date on twitter. But I’ll just steal some of their bandwidth and show some pretty pictures.

Most of the dots in this picture are one of those distant galaxies, lit up in the infrared due to its once and future stars:
ATLAS Survey
Image courtesy ESA/ATLAS Consortium

Closer to home, this is selection of star-forming regions, turbulent filaments of gas and dust:
Image courtesy ESA/Hi-GAL Consortium

Not coincidentally, Imperial’s Michael Rowan-Robinson, who has been doing infrared astronomy for several decades, appeared on BBC radio 4’s wonderful In Our Time this morning to discuss “The Cool Universe”: covering a century or so of infrared astronomy in forty-five minutes.

We on Planck won’t be coming out with any papers for quite a while. However, many members of the team gathered in Orsay, outside of Paris, this week, to discuss the progress of the observations (and our analyses) and, crucially, to start talking in more detail about the actual papers that we’ll be writing over the next few years. More generally, Planck is doing pretty well. It came out first in NASA’s latest round of evaluations (which is a significant achievement for a mission primarily run by ESA), and which we hope will also give further impetus to keep funds flowing in the UK. This is especially important as the length of the Planck mission is likely to be almost doubled, allowing us to extract even more science than we originally hoped.

I can’t say much more, except that we’ve got a lot of — very exciting — work ahead of us.

Doctors, Deep Fields and Dark Matter

Luckily, not all the astrophysics news this week was so bad.

First, and most important, two of our Imperial College Astrophysics postgraduate students, Stuart Sale and Paniez Paykari, passed their PhD viva exams, and so are on their ways to officially being Doctors of Philosophy. Congratulations to both, especially (if I may say so) to Dr Paykari, who I had the pleasure and fortune to supervise and collaborate with. Both are on their way to continue their careers as postdocs in far-flung lands.

Second, the first major results from the Herschel Space Telescope, Planck’s sister satellite, were released. There are impressive pictures dwarf planets in the outer regions of our solar system, of star-forming regions in the Milky Way galaxy, of the vary massive Virgo Cluster of galaxies, and of the so-called “GOODS” (Great Observatory Origins Deep Survey) field, one of the most well-studied areas of sky. All of these open new windows into these areas of astrophysics, with Herschel’s amazing sensitivity.

Finally, tantalisingly, the Cryogenic Dark Matter Search (CDMS) released the results of its latest (and final) effort to search for the Dark Matter that seems to make up most of the matter in the Universe, but doesn’t seem to be the same stuff as the normal atoms that we’re made of. Under some theories, the dark matter would interact weakly with normal matter, and in such a way that it could possibly be distinguished from all the possible sources of background. These experiments are therefore done deep underground — to shield from cosmic rays which stream through us all the time — and with the cleanest and purest possible materials — to avoid contamination with both both naturally-occurring radioactivity and the man-made kind which has plagued us since the late 1940s.

With all of these precautions, CDMS expected to see a background rate of about 0.8 events during the time they were observing. And they saw (wait for it) two events! This is on the one hand more than a factor of two greater than the expected number, but on the other is only one extra count. To put this in perspective, I’ve made a couple of graphs where I try to approximate their results (for aficionados, these are just simple plots of the Poisson distribution). The first shows the expected number of counts from the background alone:

So even if there is no signal above the background, seeing two counts is not terribly unlikely. Now, here’s the likelihood function for the signal rate, given their background measurement:

It peaks away from zero, so the most likely interpretation of their experiment is that they see a signal, but it’s far from conclusive.

(I should point out a few caveats in my micro-analysis of their data. First, I don’t take into account the uncertainty in their background rate, which they say is really 0.8±0.1±0.2, where the first uncertainty, ±0.1 is “statistical”, because they only had a limited number of background measurements, and the second, ±0.2, is “systematic”, due to the way they collect and analyse their data. Eventually, one could take this into account via Bayesian marginalization, although ideally we’d need some more information about their experimental setup. Second, I’ve only plotted the likelihood above, but true Bayesians will want to apply a prior probability and plot the posterior distribution. The most sensible choice (the so-called Jeffreys prior) for this case would in fact make the probability peak at zero signal. Finally, one would really like to formally compare the no-signal model with a signal-greater-than-zero model, and the best way to do this would be using the tool of Bayesian model comparison.)

Nonetheless, in their paper they go on to interpret these results in the context of particle physics, which can eventually be used to put limits on the parameters of supersymmetric theories which may be tested further at the LHC accelerator over the next couple of years.

I should bring this back to the aforementioned bad news. The UK has its own dark matter direct detection experiments as well. In particular, Imperial leads the ZEPLIN-III experiment which has, at times, had the world’s best limits on dark matter, and is poised to possibly confirm this possible detection — this will be funded for the next couple of years. Unfortunately, STFC has decided that the next generation of dark matter experiments, EURECA and LUX-ZEPLIN, needed to make convincing statements about these results, weren’t possible to fund.


Cross-posted on Andrew Jaffe’s Blog and the Planck Mission Blog.

Planck and Herschel are en route to their orbit at L2!

We were about 7.5 km from the launch, at the “Agami” viewing site. Here is my golden ticket:
Planck launch badge

We all milled around for half an hour, snapping pictures of friends, eminent scientists, and at least one Nobel prize winner, but it all went silent when they announced the last few minutes before launch. The inevitable and ignition was followed by a still, silent seven or so seconds, and then we saw the smoke and flames.
Herschel/Planck Liftoff
(Apologies for the poor quality; there were many people there with far more powerful zoom lenses than my meagre 2.5x.)

The rocket then pierced the clouds:
Herschel/Planck in the sky
Soon after, the booster rockets separated (which those 200x telephoto lenses could capture), and soon all left to see with the naked eye was the rocket’s trail:
Herschel/Planck contrail

For the rest, we had to watch the video feed from the control room, and, about half an hour later we finally heard what we were waiting for: first Herschel, and then Planck, had separated from the rocket and were on their own, off to L2. Four or five hours later, Planck’s instruments had been turned on, and the ESA team in Darmstadt was monitoring their progress. There’s a lot going on now, but we won’t have anything like scientific data for two or three months — and then our work is cut out for us.

Huge thanks to the instrument teams for their hard work for more than the last decade. Soon, the hard part for us scientists and data-analysts begins: four or so years of data coming down from the satellite, being cleaned and calibrated, building and rebuilding our (computer) model of the instrument, letting us build and rebuild our models of the Universe.

Thanks also to the HFI Instrument Principle Investigator and co-PI, Jean-Loup Puget and Francois Bouchet (and especially Hélène Blavot) for arranging this extraordinary opportunity for us scientists to see this part of the fruits of our work.

Launch Blog — Day 2: Rollout

Cross-posted on Andrew Jaffe’s Blog and the Planck Mission Blog.

Today we saw the rollout of the gargantuan Planck/Herschel Ariane 5 rocket, when they move it from its assembly building to the launchpad. Spectacular!
Planck Rollout
There are plenty more pictures, and some movies, which I’ll try to edit and post shortly. At the end of the day, I was interviewed and inadvertently kidnapped by Chris Lintott and the BBC Sky at Night team. But I am here to tell the tale (and better fed for it) and ready for the — very — big day tomorrow.

Live coverage of the launch, scheduled for 2:13pm on 14 May, at:

Pre-launch blitz

With less than a week to go before its planned launch, The Planck Surveyor Satellite has been loaded into the fairing of its Ariane 5 rocket along with its sister satellite, Herschel. It is scheduled to be rolled out to the pad on May 13, and the launch window opens on May 14 at 13:12 GMT. Within three months, it will be at the Lagrange 2 (L2) point, from where it can watch the sky with the Sun, Earth and Moon all comfortably shielded from view.

Once there, Planck will scan the sky for at least 14 months. But don’t expect to see much out of the mouths (or blogs, or printers) of Planck scientists for a while: we’ve got a full year thereafter to analyze the data, followed by a year’s “proprietary period” during which we’ll do our best to extract the most exciting science. But until then — the first rule of Planck is: you do not talk about Planck. The second rule of Planck is: you DO NOT talk about Planck. (Luckily, Herschel expects to release its pictures of the infrared and submillimetre universe much more quickly.)

For now, the European Space Agency, the UK’s Science and Technology Facilities Council, and of course us Planck scientists ourselves have been gearing up both for the scientific data — and the press.

ESA has a Herschel and Planck launch campaign page with a nifty live countdown (which users of Apple’s Safari browser can make a dashboard widget out of). Last week, STFC held a pre-launch press event in London, which got us some coverage in The Independent, The Daily Mail, The Telegraph, The Times, as well as BBC Radio and TV news. (And Sky at Night will have coverage from the launch.) We’ve also been covered in New Scientist (complete with always-exciting quotes from me).

If this media saturation isn’t enough, you can check out the page dedicated to Planck in the UK, Follow Planck on Twitter (and Herschel too), read the Planck Mission Blog (there’s one for Herschel, too).

As for me, I’m taking a break from this term’s teaching — off to French Guiana next week for the launch (barring further delays). For those of you less lucky, it will be visible on satellite tv and streamed by ESA. I’ll do my best to keep up the twittering and blogging, probably cross-posting from here to the Planck Mission Blog. Wish us luck!

STFC Consultation results

No time for a full blog post, but I wanted to point out the results of the STFC Consultation, now available.

Some of my favorite projects like AstroGrid seem to have not fared too well (the consultation panel rated it highly, but PPAN, responsible for the final ranks, disagreed). Nonetheless, Imperial Astrophysics projects like Planck, Herschel, Scuba II, UKIDSS, LISA Pathfinder and XMM Newton appear to have survived the cut. However,

It is important to stress that these reports are not the final conclusions of the Programmatic Review. These conclusions will be reached by STFC Council using these reports to inform their decision-making.
More later as the repercussions become clear.

Big Smoke Science

In his comment on last week’s post, fellow physicist blogger Tommaso lets me know that he’ll be attending a meeting that we’re hosting here at Imperial College next week, Outstanding questions for the standard cosmological model. We’ll be casting a critical eye over current cosmological models and data, but I expect most of us will come to the conclusion that the whole structure is surprisingly weather-sturdy.

In fact if you’re any sort of astrophysicist, particle physicist or cosmologist, Imperial Physics is likely to have a meeting for you in London over the next few months. In addition to “Outstanding Questions”, we’ll have

  • A meeting making plans for XEUS, April 2-4. XEUS is the X-Ray Evolving Universe Spectroscopy mission, an X-Ray telescope satellite under consideration by the European Space Agency;
  • PASCOS (Particles, Strings and Cosmology) 07, July 2-7, the latest in a series of meetings examining the interface between theoretical particle physics and cosmology; and
  • From IRAS to Herschel-Planck, July 9-7. This is a special meeting, in honor of Professor Michael Rowan-Robinson on his 65th Birthday. Michael is currently the head of our Astrophysics group, and is one of the founders of the field of sub-millimeter and infrared astronomy, using long-wavelength photons to observe those parts of the Universe often hidden behind clouds of dust — veiled stellar nurseries where indeed a significant fraction of the stars were formed in the universe’s first few billions of years. IRAS was the first large-scale infrared satellite, and Herschel (along with its sister spacecraft, Planck, about which you’ve heard plenty here) will be the next ambitious project to observe the whole sub-millimeter sky.
Hope to see you in London…