An Ariane 5 booster successfully launched ESA’s Planck and Herschel satellite observatories from French Guiana yesterday. (Photo slideshow from Der Spiegel here.)
With a 3.5m primary mirror, Herschel is the largest space telescope launched to date, and has more than twice the light-gathering power of Hubble’s 2.4m mirror. Hubble is primarily a visible-light instrument, though, while Herschel is a far-infrared and sub-millimeter telescope, leaving Hubble still the most powerful visible-light space observatory. (Don’t miss the visible-light and infrared images of Orion on that JPL page.) Herschel will be dwarfed by the 6.5m mirror of the James Webb Space Telescope, but the Webb is not scheduled to launch until 2014. Herschel’s 2000 liters of liquid helium should keep it in operation for three years.
The Planck Surveyor isn’t an optical telescope at all; it’s a microwave instrument, destined for an orbit around the L2 Lagrange point, 1.5 million kilometers from Earth. It has an expected service life of only fifteen months due to the limited quantity of liquid helium coolant it is able to carry, but during that time it will examine the cosmic microwave background in unprecedented detail, with three times the resolution and ten times the sensitivity of the Wilkinson Microwave Anisotropy Probe and in almost twice as many frequency bands, in most of which it is also able to measure photon polarization.
Between the two, we should be able to expect some very interesting observations over the next three to four years. We may get more than that, but it’s unlikely we will see the kind of extended lifetime from Herschel and Planck that has been managed with Hubble, as Herschel and Planck will be too far from Earth for servicing and resupply.
The batteries that the current — and final — Hubble service mission is replacing are 19 years old, and were planned to last for five. This mission, in addition to replacing all of Hubble’s batteries, is also replacing Hubble’s data router, the Wide Field and Planetary Camera (replaced with the new Wide Field Camera 3), and all of Hubble’s stabilizing gyros, and will also install one new instrument, the Cosmic Origins Spectrograph, the most sensitive spectrograph ever flown in space.
