2010-03-22T10:52:44Z Ken Copyright 2010, Ken SPHPBLOG here.
]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry100318-191313 2010-03-18T00:00:00Z 2010-03-18T00:00:00Z
Since the meetings are supposed to be work sessions, we all bring our computers and try to act antisocial:



A couple of colleagues kept asking what sort of bizarre meeting this was, since whenever they went by the room, nobody seemed to be talking.

I only got to sneak away once, to see the Wipple Museum of the History of science. But they've got a telescope made by Herschel, after whom our sister satellite is named:

,

and I did get a picture of the "Mathematical Bridge":
.

I always wonder why the French and the English pretend to hate each other so much:
;

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]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry100215-224843 2010-02-15T00:00:00Z 2010-02-15T00:00:00Z


He was one of the most respected people not only on the Planck project, but also in the CMB field, cosmology and physics in general. He led the development of some of the most important technical advances in the field, and used these advances to make some the most important cosmological measurements ever. His teams have made measurements of such mind-boggling things as the geometry of the Universe and the energy content of the Universe. He led the design and creation of the heart of the Planck/HFI instrument. His suicide is a staggering shock and a tragic loss for all of us who knew him.
]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry100123-175524 2010-01-23T00:00:00Z 2010-01-23T00:00:00Z
The center is located in Orsay Ville, a southern suburb of Paris



It's about an hour's ride on the suburban metro here -- not far, but those of us who live in the center grumble sometimes about having to go "all the way to Orsay" anyway. Never mind that it's still far easier for us than for the people living in other cities and countries, who are nevertheless supposed to put in some operations duty as well (though those in Paris do more).

The Center is housed in the Space Astrophysics Institute on the South campus of the University of Paris:



The center itself is really just one room with a bunch of computer terminals, where we can display much of the information coming down during the download period. Here is a picture of the room with Karin and Maryse:



It was exciting coming here the first couple of times, but now it's really just a chore. We come in about a half hour before the data starts flowing. As soon as the download starts, we check that data is flowing and that some of the basic temperatures and pressures are within nominal range. We process some of the data downloaded from the day before and check some of these to make sure there haven't been any strange events.

Most of the data we get was actually taken during the preceding day, stored onboard, and only downloaded to us at this time. But we do get some "near real time" data that we also check, to get an idea of how the instrument is doing at that moment. The whole session is about three-and-a-half hours, but I have to admit that a large fraction of that is spent surfing the web, once we're sure the instrument is behaving nominally. We do, however, stay during the entire period -- you'd feel really stupid if something went wrong while you were there and you didn't notice or do anything about it!

]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091126-222005 2009-11-26T00:00:00Z 2009-11-26T00:00:00Z
It's a bit out of the way, and sort of a pain to get to, but is a pretty unique setting.



The ruins of the 15th century castle give the area its name: Villafranca del Castillo.

]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091118-235322 2009-11-18T00:00:00Z 2009-11-18T00:00:00Z

The picture above shows a bunch of the Planck team milling around on the street outside a restaurant in Bologna, where we ultimately had out "social dinner" yesterday.

This is the first time the entire team has met since data has started coming down, so people were excited. There are some things that will require a lot of work, but the basic feeling seemed to be something along the lines of "Wow, I never believed it would work this well."

One hiccup so far has been that some people seem to have been "pushing" our "communication policy" to its limits. We are not supposed to show the data outside of the consortium until it has been thoroughly processed and validated. The project scientist showed this viewgraph to try to make the policy clear:


So, since we can't talk about the Planck data yet, all I can do is show you the little trinkets we got at the meeting. It seems the Netherlands (where there is a big European Space Agency installation) has actually issued stamps with Planck and Herschel on them:


Planck is the most sensitive CMB satellite ever launched, but more important than that, since there are scientists from all over Europe working on it, it's also a fabulous way to exchange commemorative euro coins, if you do this sort of thing (-:
(these are from Anne from Finland).

I had time for only one mildly touristy visit, to the Asinelli Tower in the center of Bologna:


]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091106-182313 2009-11-06T00:00:00Z 2009-11-06T00:00:00Z
Unfortunately, the answer is no. Basically, Planck is much, much, much further than the International Space Station (ISS). Too far to be seen.

For comparison, the ISS is in low-Earth orbit. This means it is usually a couple of hundred miles from the surface of the Earth. By contrast, Planck is almost one million miles from the Earth. Very roughly, being able to see Planck would be like being able to see a person at the distance of the moon.

For the aficionados: While I was a student, the COBE satellite was visible a few times, and Dave Wilkinson and I went up to the roof of the physics building and watched it pass by once. He said he liked the idea that something he had helped make would be up in the sky long after he was gone.]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091021-095016 2009-10-21T00:00:00Z 2009-10-21T00:00:00Z ESA's CMB History Page, and noticed that it says "The first space-based measurements of the CMB were carried out with NASA’s Cosmic Background Explorer (COBE) satellite."

This is wrong.

The first satellite (that I know of!) designed and deployed to study the CMB was the Soviet Relikt-1 mission, which was launched in 1983. The COBE satellite was not launched until 1989. Most astrophysicists today believe that the COBE/DMR instrument was the first to detect primordial anisotropies in the CMB, but the RELIKT team did claim that they had detected primordial CMB anisotropies in 1992, just before the the COBE team published. This claim is usually discounted today.

(If you notice that ESA corrects their page, please let me know.)
]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091016-144136 2009-10-16T00:00:00Z 2009-10-16T00:00:00Z here -- it's in French).

In it, he recounts how we almost missed a problem during testing which would have ruined the mission. Basically, on the last day of testing (there was about a month of testing before the launch), the instrument team found a helium leak that could have compromised the project. It only appeared on the last day of testing. If it had 'held out' just a day longer, we would have had no idea that it existed before the satellite was beyond reach and we would not have been able to repair it.

The basic problem was a faulty pressure regulator. There were still hiccups even after the problem was found. There aren't a lot of these kinds of regulators approved for space use, and the usual lead time needed to get one of them is eight months. An extra eight-month delay in the launch would have meant a lot of frustration for us, and a lot of money for the European Space Agency. But in the end they found replacements by "borrowing" similar regulators which had been approved for another satellite. ]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091009-174305 2009-10-09T00:00:00Z 2009-10-09T00:00:00Z















]]> http://www.apc.univ-paris7.fr/~ganga/Bulahg/index.php?entry=entry091008-125647 2009-10-08T00:00:00Z 2009-10-08T00:00:00Z