Artist's concept of SNAP spacecraft.

SNAP, the SuperNova/Acceleration Probe, is led by Saul Perlmutter of Lawrence Berkeley National Laboratory in Berkeley, California. Perlmutter was lead scientist for one of the two groups that discovered cosmic acceleration in 1998.

SNAP will use a 1.8-meter optical/infrared telescope with a CCD detector that has a billion pixels (the CCD in digital cameras have "only" a few million pixels, about 1,000 times fewer than SNAP's camera). SNAP's powerful camera could pick up about 2,000 Type Ia supernovae each year over a wide range of distances. Such a large number of detections—about 200 times the current annual rate—would provide a solid handle on how our universe's expansion rate has evolved over cosmic history, which in turn indicates how the influence of dark energy has changed with time. This result would enable scientists to rule out some theories of dark energy's nature, while strongly supporting others.

But SNAP will also conduct studies that take advantage of gravitational lensing, a phenomenon predicted by Einstein's General Theory of Relativity. SNAP will measure the apparent displacement of distant galaxies when the mass of a foreground object bends their light like a lens. This will enable the SNAP team to measure dark energy's influence on the distribution of matter in our universe. This part of the survey will cover hundreds of thousands of square degrees of sky each year.