Results tagged “Planck”

In the Sky (at Night)

Despite my almost eight years in Britain as an astronomer, I suppose I have to be embarrassed to admit I’ve never actually watched “The Sky At Night”, apparently the longest-running show on television (possibly in the whole world, not just the UK). But I’m watching this evening’s episode, mostly because I’m on it. I was filmed during last month’s trip to the Planck launch. As always, it was painful to realize the fat figure with the bad posture and annoying voice was actually me. But it was fun to watch Patrick Moore do his studio interviews, with a style and on a set neither of which seem to have changed since the 1970s.

But it was beautiful and moving to see the launch again, and to watch the much closer movies and pictures than I was able to get on the day. Since then, parts of Planck have been slowly turned on, cooled down, and checked out. Everything is working well so far; we’re looking forward to the first data in a little more than two months. It’s going to be a long summer.

The episode will briefly be available on BBC’s iPlayer, but more of my cringeworthy discussion of Planck in a different context is up on YouTube; check out the next post for much cooler cosmology video from a more photogenic cosmologist with a better voice.


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:

Launch blog — day 1

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

Today was spent in Cayenne — the capital of French Guiana, where most of the hotels are located, and Kourou — home of ESA’a Centre Spatial Guianaise. We climbed up a nearby peak for a look over the Spaceport, but mostly we saw hand-sized spiders and a hazy view of what some very large if indistinct structures.

Closer up, we (about a hundred scientists, obviously more than the ESA staff were used to) got a tour of the facilities, starting in the “Jupiter II” control room where the launch will actually be, um, controlled:
Arianespace control room

We also saw the launch sites for the Vega and Soyuz rockets, and of course for our own Ariane 5:
Ariane launch pad
But better will be tomorrow, when we get to see the rocket — our rocket — rolled the few kilometers from its current building to the pad in preparation for Thursday’s (hoped-for) launch.

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!

Loading Planck

The Planck Surveyor Satellite has finished its assembly and testing in Liège, Belgium, and this week was loaded onto a Volga-Dnepr Antonov AN-124 plane, and sent to Kourou, French Guiana, location of the Centre Spatial Guyanais (one of the few places near the Equator politically connected to Europe). It’s due to be launched in tandem with Herschel on April 16. Here are some pictures of the “Planck Transport and Storage Container” making its way on a “Convoi Exceptionnel” to the airstrip. These photos came to me third-hand, so my apologies and thanks to the unknown (to me) photographer.
342-Planck entering container in CSL 344-Truck in position 347-Planck loaded on truck 352-Transfer on ramp 354-Planck inside the plane

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.

In its continuing bid to take over all aspects of science communication, Nature magazine (or more properly, an alliance between Nature Network and the Royal Institution) will be hosting a European Science Blogging conference in August or September.

Right now, however, I’m in Norway. In addition to discussing how we’re going to measure the CMB power spectrum with Planck, I’ve already eaten a slab of reindeer, ran for an hour up and down the snowy hills, and sweated in a sauna.

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…

Planck scanning strategy

OK, this is going to be very technical. In his comment to my last post, my colleague Ned Wright asks a couple of important questions about the way that the Planck Surveyor satellite is going to observe the sky. In the spirit of Mark Trodden’s question about the use of blogs in the research process, let’s see if we can answer these questions in a way that will satisfy Ned (who knows more about observing the CMB than most people on the planet) and not be completely opaque to the rest of my readers. Ned asks:

What is the current plan for the Planck scan pattern? I see this quote from the 2005 Blue Book:

The spacecraft will spin at 1 rpm around an axis offset by 85 degrees from the telescope boresight, so that the observed sky patch will trace a large circle on the sky (Dupac and Tauber, Astronomy & Astrophysics 430, 363, 2005)….

As the spin axis follows the Sun, the circle observed by the instruments sweeps through the sky at a rate of 1 degree/day. The whole sky will be covered (by all feeds) in a little more than 6 months; this operation will be repeated twice, resulting in a mission lifetime of around 15 months.

This describes a terrible scan pattern that may ruin Planck’s ability to measure the low-ell polarization signal that is essential for deterimining tau.

And the claim of covering the whole sky is wrong since as described, a 5 degree radius about each ecliptic pole is left out. That’s most of the sky, but not all.

The inner quote describes the way Planck will scan the sky — every minute, the satellite will observe a circle with an opening of twice the 85 degree angle described in the quote (a great circle that goes through the poles would have twice 90 degrees). Here’s a picture (from Dupac and Tauber 2005) of Planck’s location and the way it will scan the sky:


Ned is worried about two things, but I’ll discuss them in the opposite order.

He points out that the scan strategy leaves “holes” about five degrees across in the North and South poles. Indeed, the so-called “nominal” scan strategy above does suffer from this (although this is somewhat ameliorated by the fact that Planck has many detectors all looking at spots up to eight degrees from one another on the sky, so in fact those holes are largely filled). A more realistic scan strategy, as described in the paper by Dupac and Tauber mentioned above, will dip up and down out of the plane defined by pointing away from the sun, earth and moon. The exact way we perform these dips (how quickly and with what pattern) remains to be decided, but in any event will fill in those holes. For one possible strategy, the coverage looks like the following, from the same paper (yellow and red areas are observed more than blue and green):


Second, and most important, are the effects of long-term drifts in our detectors. An instrument like Planck can’t just look at a point in the sky and measure the temperature directly. Instead, the background level coming out of our detector is drifting over time, and these drifts can actually be large compared to the tiny CMB signal we’re trying to measure (for aficionados, this is often known as 1/f noise, after the power spectrum of the noise often observed in cases like this). This means that it’s relatively easy to measure the relative temperature of points that are observed nearby in time — since the background hasn’t drifted by much. But it’s much more difficult to measure relative temperatures over long periods of time. Therefore (as Ned points out), it might be difficult to observe patterns on large angular scales, across many individual rings. This is “the low-ell polarization signal that is essential for deterimining tau”: only on these scales can we observe the effects on the CMB of the very first objects to “light up”, more than twelve billion years ago.

This difficulty can only be ameliorated by “cross-linking” — making sure that you observe the same point at many different times. This lets us recalibrate the baseline of the detector every time we revisit that point or, better, set of points. The experiments that Ned Wright himself has worked on, COBE/DMR and WMAP, cleverly achieve this by the very complicated way they observe the sky.

Planck will definitely have a harder time, since its cross-linking only occurs at those points near the poles with many repeated observations. This puts a strong constraint on our detectors: they can’t drift very much over the one minute it takes to make a single circular scan. In this article, my Planck colleagues Christopher Cantalupo, Julian Borrill & Radek Stompor show that we can indeed handle these problems for more-or-less realistic kinds of noise.

To be sure, the real world is always more complicated than our simulations. The hard part will be dealing with what we euphemistically call “systematic effects” — roughly speaking, those errors that we don’t know how to describe very well, or that we don’t know about when we first fly the satellite. The ability to find these systematic effects is another reason why we want both very small known sources of error and the greater redundancy afforded by cross-linking, by comparing the same signal seen under very different conditions at different times during the mission.

Undoubtedly, we will encounter such unexpected sources of noise when we confront real data from Planck late next year, but we hope that the quality of our detectors, combined with the design of our scan strategy, will give us enough extra information to account for these inevitable problems. (But I probably won’t be able to tell you for sure until about 2011 when we’re due to make our first release of Planck results!)

Update: Further comments from Ned below. Discretion being the better part of valor, I shan’t comment on why these decisions have been left until now (although it is certainly arguable that flexibility is a good thing), and why Ned himself wasn’t consulted (suffice to say I wasn’t a member of the team that far back). However I must certainly agree that Planck’s ability to measure the polarization of the CMB would certainly be better if, as he suggests, the scan strategy visited pixels from many different directions, rather than approximately along lines of “longitude”; the measurement of polarization depends on just those directions, and having many different such measurements at the same location would make it easier to account for the aforementioned 1/f noise and possible systematic effects. Indeed, the experience of the WMAP team teaches us the difficulties of the measurement of large-scale polarization. We do believe that our raw sensitivity will be such that we can recover this polarization sufficiently accurately, but the proof will be in our results, and not in any simulations we do beforehand.

Planck Press

With only [sic] about a year and a half to go before launch, The Observer has a story on the ESA Planck Surveyor mission that I’ve spending much of my time working on over the last several years. (In fact, I have to spend the day writing a program that will play a very small part in working out exactly where the satellite’s detectors are pointing while it’s spinning around in space.)

Update: The BBC has got an article that goes more in-depth (and with more Nobel prize-winners, but less of me…).

The New York Times opines on the physics Nobel:

…The award is richly deserved, and the agency deserves great credit for making the work possible. Too bad the program that yielded these pioneering discoveries was reined in not long ago so that NASA could pour billions of dollars into resuming shuttle flights, finishing the international space station, and developing spacecraft to pursue the Bush administration’s ambitious space exploration program.

…Huge teams of government and academic researchers measured and analyzed the cosmic microwave background radiation that permeates the universe. Their findings provided strong support for the Big Bang theory of the origins of the universe, and turned cosmology, previously rather speculative, into a precise science. The discoveries have been hailed as one of the greatest scientific advances of the past century.

The COBE satellite was part of NASA’s Explorers Program, which uses small satellites to conduct important studies that don’t need gigantic, costly space platforms. Yet these and similar small-scale missions were disproportionately cut to free up money for more grandiose programs. The Nobel award suggests that NASA needs to rebalance its portfolio, a task the agency says is in progress.

Amazingly, COBE’s results didn’t come from a “huge team of … researchers”, but a relatively small, focused group of a few dozen scientists. More recent results from COBE’s successor, the WMAP satellite, came from similarly-sized teams; contrast this to the 400 or so working on ESA’s Planck Surveyor Satellite. Unfortunately for the 400 of us, two important things I’ve learned in my time as a scientist is that scientists are terrible at being managed—and even worse at being managers.

Quick update

Sorry I’ve been silent… here’s a quick update:

I’m in Pasadena, California, working at JPL and Caltech on various tasks related to the Planck Surveyor Cosmic Microwave Background satellite, to be launched in a couple of years (which means “soon” in this game).

Mmmmm!I’m sure you’re waiting breathlessly to hear my commentary on such crucial subjects as Pluto’s planetary status (or lack thereof; but really, who cares?), the nature of the Dark Matter, the cosmological dark ages, and the fine cuisine of Roscoe’s House of Chicken ‘n Waffles.

But you’ll just have to wait.

Cosmology in the Mediterranean

Like fellow-blogger Mark Trodden , I’ve just spent the week at scientific meetings in Ischia, an island off the coast of Naples. The first half of the week was for the yearly consortium meeting of the Planck Surveyor satellite. Although still endangered by further delays, we expect the satellite to be launched in early or mid 2008, and by then we have to be ready to analyze the data from Planck as it gets transmitted, just a few bits at a time, from the satellite at the “L2” point, 1.5 million kilometers from the Earth, a place where the sun, earth and moon will all be in a small area of the sky — so it’s easier to shield the satellite, which is measuring temperature differences of a few parts in a hundred thousand on top of a background just three degrees above absolute zero.

Of course, at an experts-only meeting like this, we didn’t discuss the exciting scientific prospects so much as the details confronting us today: planning how the mission is going to scan the sky, how we’re going to measure the instrument’s properties in situ, and how we’re going to transform the terabytes of data it will produce into information about the universe.

After the detailed work of the consortium meeting, we turned to the scientific side of cosmology as it is today, hearing about details of early universe physics, dark matter, and, especially, Planck’s predecessor, WMAP, from Mike Nolta.

Pompeii 1I even got some time free at the end to spend a day at Pompeii, and at the National Archaeological Museum. Coming from a country only a couple of centuries old, walking through two-thousand year-old streets, it was remarkably easy to imagine the ancient Romans peddling their wares, living their lives, eating and drinking, just like us (except for the slaves, of course…). (More pictures here.)

To top it all off, I returned to find Spring finally arrived in London, my favorite plants in bloom at last. But now, no rest for the weary: after about a day and a half back home, it’s off to another meeting. But that’s an entry for later.

Management, Money, Media

Wednesday was a busy day of politicking and schmoozing (as opposed to research and teaching, which is what I actually get paid to do).

I spent the morning at a meeting reviewing the current status of developments for the Planck Surveyor satellite here in the UK (Planck will measure the temperature of the Cosmic Microwave Background, relic radiation from the Big Bang). Unfortunately, as is common in these ambitious and exciting projects, not everything is quite going according to plan. We need to cool parts of the satellite down to a mere four degrees above absolute zero. This has become relatively easy to do in a laboratory, but is still very difficult up in space, where you have stringent requirements on size, weight and power and, most importantly, where you can't fix anything once it's been launched. So this part of the project is over budget, late, and indeed faced with technological problems (like, how do you build it so it can survive shocks equivalent to 3000 times the acceleration due to gravity?!).

Part of the problem is that scientists, despite thinking that we know how to do everything, are generally bad (or at least untrained) managers, and even worse “managees” -- we don't like being told the way to do things (I can certainly speak for myself here on both counts, but at least understanding that I have these problems might be the first step towards solving them.)

The rest of the day was much more pleasant. First, I went to a short meeting debriefing those of us who participated in the Royal Society's “MP-Scientist” pairing scheme. It was great to see and talk with my cohorts from November, and then we all headed down watch the wonderful Faraday Lecture by Professor Fran Balkwill on Ovarian Cancer, which was neither dry nor depressing. The evening ended with the “Scientists Meet the Media” party hosted at the Royal Society by the Daily Telegraph and Novartis (who paid for the champagne, apparently). There were scientists from crusty old white-haired Fellows of the Royal Society on down to youngish faculty members like me and media types from TV, newspapers, magazines and science journals. Power couple Gia and Brian were there, as were Adam Hart-Davies in a frightening bright blue suit, Robert Winston in a tux, all presided over by astrophysicist Lord Martin Rees, new president of the Society. We scientists tried to keep up, but the journalists did their best to live up to their hard-drinking reputation, aided by the free-flowing wine and very scarce food. Usually the scientists are the ones with the privileged information, but on a night like this, the journalists seemed to be in control, we scientists in full media-slut mode, our not-so-secret desire for fame, or at least recognition, on show.

Update: Here's a report from the Telegraph, focusing on the celebrities at their party...