BY DR EMILY BALDWIN
Posted: 6 May, 2009
ESA's two missions to probe the far reaches of the Universe are gearing up to launch from the Guiana Space Center in French Guiana on 14 May.
The two satellites, Herschel and Planck, will share a ride aboard the same Ariane 5 rocket. Shortly after launch they will separate and follow different trajectories to the second Lagrangian point of our Solar System, 1.5 million kilometres from Earth. “The missions are quite different, but they’ll hitch a ride to space together,” says Ulf Israelsson, NASA project manager for both Herschel and Planck. “Launch processing is moving along smoothly. Both missions’ instruments have completed their final checkouts, and the spacecrafts’ thruster tanks have been fueled.”
Planck will teach us about the conditions in the very early Universe. Image: ESA.
Planck will be dedicated to answering fundamental questions about the origin and evolution of the Universe by peering back to just 400,000 years after the Big Bang gave birth to existence. It will spend at least 15 months mapping the cosmic microwave background, light from the primordial soup of particles that eventually evolved to become our modern-day Universe.
“The cosmic microwave background shows us the Universe directly at age 400,000 years, not the movie, not the historical novel, but the original photons,” says Charles Lawrence, NASA project scientist for Planck at JPL. “Planck will give us the clearest view ever of this baby universe, showing us the results of physical processes in the first brief moments after the Big Bang, and the starting point for the formation of stars and galaxies.”
The Herschel Observatory will pick up the baton from Planck by focusing on the earliest stages of galaxy, star and planet formation. It boasts the largest mirror ever flown into space at 3.5 metres, and will collect long-wavelength light in the infrared and submillimeter range.
Herschel has the largest mirror ever flown into space. Image: ESA/D. Ducros.
“We haven’t had ready access to the wavelengths between infrared and microwaves before, in part because Earth’s atmosphere blocks them from reaching the ground,” says Paul Goldsmith, the NASA project scientist for Herschel. “Because our views were so limited before, we can expect a vast range of serendipitous discoveries, from new molecules in interstellar space to new types of objects.” At these longer wavelengths the Universe’s coolest objects - dusty, developing stars and galaxies - will shine brightly. In visible light, these objects appear as dark impenetrable blobs, but Herschel will reveal what is going on beneath that dusty veil.
Both Planck and Herschel will be cyrogenically cooled to a few 10ths of a degree above absolute zero.
To read more about the missions, see our six-page feature in the April issue of Astronomy Now magazine.