Planck and Herschel Exclusive Interviews
Herschel Project Scientist
From left to right: Tom Phillips, Hal Yorke, Pierre Encrenaz, Paul Harvey, Martin Harwit, Matt Griffin, Göran Pilbratt, Christoffel Waelkens, José Cernicharo, Albrecht Poglitsch, Jackie Fischer, Peter Barthel, and Thijs de Graauw. Missing in the picture Gerry Crone and Laurent Vigroux.
Could you explain the logistics of the “double launch” of Herschel and Planck?
The two spacecraft are two payloads on the same launcher and the launcher itself operates for 25 minutes, then two minutes later the Herschel spacecraft will be released, and a few minutes later the Planck spacecraft will be released. They are headed for similar but not the same orbits around the L2 point. Planck will inject itself into a smaller orbit which costs a lot in terms of fuel, but that is not necessary for Herschel, therefore Herschel will be in a lot bigger orbit.
Herschel and Planck will still be linked though, with Herschel destined to follow up on sources detected by Planck. What sort of sources are you expecting to follow up on?
There will be a multitude of sources, but the observations will mostly be for calibrations. They [the Planck mission team] want us to look at certain sources so they can calibrate their observations and from a more direct scientific point of view, we can provide deeper observations and observations with higher resolution for their sources. But this is not linked through the missions; Planck investigators will have to propose for Herschel observing time just like any astronomer would have to do, and we already have one such proposal.
The observing programs cover a wide range of topics. How are they selected?
Each observing program in a sense is free standing, people own a certain amount of observing time, they do their observations and they try to answers the issues they have identified in their proposals. The way the proposals are chosen is part of making sure that all aspects of what Herschel can do are addressed properly.
How far back will Herschel be able to see?
Will you also make measurements of the infrared background?
The infrared background looks diffuse but in principle can be resolved into contributing sources like galaxies. We will be able to resolve more of the IR background than has ever been done before because of the simple fact we have a higher resolution at these wavelength.