Göran Pilbratt Discusses the Herschel Space Observatory

Emerging Research FRonts Commentary, April 2011

Göran Pilbratt
Göran Pilbratt in front of a Herschel scale model in ESTEC in connection with the conference "400 years astronomical telescopes," held in ESTEC in October 2008. Photo CREDIT: Fred Kamphues.

Article: Herschel Space Observatory An ESA facility for far-infrared and submillimetre astronomy

Authors: Pilbratt, GL;Riedinger, JR;Passvogel, T;Crone, G;Doyle, D;Gageur, U;Heras, AM;Jewell, C;Metcalfe, L;Ott, S;Schmidt, M
Journal: ASTRON ASTROPHYS, 518: art. no.-L1, JUL-AUG 2010
Addresses: ESTEC SRE SA, ESA Res & Sci Support Dept, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands.
ESTEC SRE SA, ESA Res & Sci Support Dept, NL-2201 AZ Noordwijk, Netherlands.
ESTEC SRE OA, ESA Sci Operat Dept, NL-2201 AZ Noordwijk, Netherlands.
ESTEC SRE P, ESA Sci Operat Dept, NL-2201 AZ Noordwijk, Netherlands.
(Addresses have been truncated)

Göran Pilbratt talks with ScienceWatch.com and answers a few questions about this month's Emerging Research Front paper in the field of Space Science.

SW: Why do you think your paper is highly cited?

The paper describes the Herschel Space Observatory—Herschel for short—which is the most recent space observatory of the European Space Agency (ESA). Herschel is the result of the dreams and efforts of a large number of people in academia, ESA, and industry, starting 30 years ago.

Herschel was launched on 14 May 2009, and began doing science in earnest about half a year later. Even the very initial observations have generated a plethora of interesting results in a number of areas in astronomy, including the study of objects in our solar system, the birth and death of stars in our own Galaxy, and all the way to galaxies as they were when the universe was a quarter its present age. Thus, Herschel already has a large user community producing significant numbers of papers in the literature, including papers in Nature and Science.

SW: Does it describe a new discovery, methodology, or synthesis of knowledge?

Herschel has been designed to provide the largest astronomical telescope of its kind ever flown in space, and it also pushes into one of the last poorly explored parts of the electromagnetic spectrum, the far infrared and submillimeter.

Simply put, with a 3.5 m diameter Cassegrain telescope and a set of novel instruments it extends the envelope of possible observations to where nobody has been before. A larger telescope provides higher angular resolution at a given observing wavelength and also a greater collecting area, giving you higher sensitivity. All Herschel's predecessors in space had telescopes smaller than a meter in diameter, so we are really talking a big step forward here.

When it comes to wavelength coverage Herschel covers about 55-670 micron, the region beyond around 200 micron was never observed from space before the way Herschel can do.

SW: Would you summarize the significance of your paper in layman's terms?

Göran Pilbratt
Baby stars in the Rosette Cloud (more). ©European Space Agency, used with perrmission

View more images.

The paper is really a descriptive paper about the mission. It describes the Herschel satellite with its telescope and instruments and how it works.

One of the defining properties of Herschel is that while its telescope is passively cooled, this way we could make it so large, the instrument focal plane units, where the detectors are, are cooled by sitting inside a superfluid helium cryostat. This is really a kind of thermos bottle where helium at a temperature of only 1.65 degrees above absolute zero is slowly evaporating, and, in the process, creating the required operating environment for the instruments.

The paper also provides information about the ground segment; it is important to realize that the Herschel satellite is "just" the space segment in the observatory. In order to use the observatory astronomers need information, tools, and support. Finally, the launch and the first part of the mission and the achieved in-flight performance are described.

SW: How did you become involved in this research, and how would you describe the particular challenges, setbacks, and successes that you've encountered along the way?

I became seriously involved 20 years ago—frankly, I was the right person in the right place at the right time. It happens. A space project has its ups and downs; it is never boring and always tiring. Clearly, a particular success was the making of, and, above all, the testing and integration of the groundbreaking large telescope.

The one moment that stands out in my memory is the very first Herschel observation displayed on a computer screen, in one image confirming that we had a working observatory. That happened one month and one day after the launch and will never go away!

SW: Where do you see your research leading in the future?

In terms of operational lifetime Herschel is now about half-way through its in-flight mission, although I should add that only a small part of its scientific data have been published at this point. When all the helium is gone and the cryostat is empty Herschel will no longer function, in the sense that it will no longer be capable of making any observations. But this is not the end of Herschel. The data it has generated will be there for years to come and for all astronomers to use.

We know how important this is by analogy with previous space telescopes. Thus we are already in the process of doing everything we can to make this phase of the mission as productive as possible by providing the best possible archive and tools to the community. And of course, ideas for the next-generation telescopes exist and are being worked on!

SW: Do you foresee any social or political implications for your research?

It is my experience that astronomy in general tends to interest people everywhere and is usually non-controversial. Also by its nature of "big science" it tends to make, even force in some sense, people to collaborate. Herschel is a case in point which is very stimulating and interesting from a personal perspective, but being a very international project it also has interesting social and political dimensions. When it comes to the (wo)man in the street, I hope we can transmit at least some of the excitement of discovery to most everyone.End

Göran L. Pilbratt
Herschel Project Scientist
European Space Agency (ESA)
Astrophysics Missions Division
Research and Scientific Support Department
European Space Research and Technology Centre (ESTEC)
Noordwijk, The Netherlands



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