Projects

SNAP, the SuperNova/Acceleration Probe, is an experiment designed to learn the nature of dark energy by precisely measuring the expansion history of the universe. At present scientists cannot say whether dark energy has a constant value or has changed over time, or even whether dark energy is an illusion, with accelerating expansion being due to a gravitational anomaly instead.

SNAP is led by Saul Perlmutter of Lawrence Berkeley National Laboratory in Berkeley, California. SNAP is an optical/infrared mission that would detect thousands of Type Ia supernova plus conduct weak-lensing studies. Weak lensing measures dark energy's effect on the distribution of matter by tracing the apparent displacement of distant galaxies when the mass of a foreground object bends their light.

NASA's Beyond Einstein program and the U.S. Department of Energy will support a probe to investigate dark energy, the Joint Dark Energy Mission (JDEM) - and SNAP was one of the three concepts selected in 2006 to go forward with an advanced mission concept study.