Projects: The SuperNova / Acceleration Probe (SNAP)

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SNAP is a proposed space-based experiment to study the nature of Dark Energy using two techniques: observations of distant supernovae and measurement of an effect known as weak lensing of distant galaxies. SNAP is a leading contender for the NASA/DOE Joint Dark Energy Mission (JDEM), which is part of NASA's Beyond Einstein program. The project is led by the Lawrence Berkeley National Laboratory and includes a number of participating institutions, including Fermilab.

"Dark Energy" is term used to describe a hypothesized form of matter that comprises about 70% of the universe today. The strongest evidence for the existence of dark energy comes from the discovery of the apparent acceleration in the expansion of the universe, done using observations of nearby and distant type Ia supernovae. Dark energy also solves another puzzling problem, which is that observations of the microwave background indicate that the density of the universe is close to the "critical density", but the total amount of matter identified so far, including "dark matter", falls far short. The nature of dark energy is unknown and presents a fundamental challenge to both cosmology and particle physics.

The SNAP mission consists of a wide-field, 2 meter class telescope that will be placed in an L2 orbit. The focal plane will be tiled with an array of optical and infrared imaging detectors. The planned 4 year mission will be split between a survey of a small area of sky to detect and measure 2000 type Ia supernovae and a wide area survey that will be used to measure distortion of galaxy images due to "weak lensing" by intervening matter. The combined surveys will allow the properties of dark energy to be improved by a factor 10 compared with today's measurements.

Fermilab's participants in SNAP include over 20 scientists and engineers. The main areas of contribution include R&D for calibrations, simulation software, calibrations, radiation shields, mass memory electronics, and CCD packaging.