A Dark Energy Task Force (DETF) has been established in the United States by the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the Department of Energy (DoE) to deal with the many projects underway and soon to be underway for the search for dark energy.

According to studies made with cosmic microwave background (CMB) radiation, which is radiation left over from the Big Bang, the explosion that created the universe, the universe must be composed of a certain amount of energy and matter. All the visible universe and dark matter (a theorized type of matter that is not observable because it does not emit or reflect electromagnetic radiation, at least so scientists can detect it with current devices) makes up about 30% of that energy and matter, while dark energy makes up the other 70%.

Some of the proposed projects to search for dark energy are discussed briefly below.

The Dark Energy Survey (DES), proposed by Fermilab in 2004, is expected to start looking for dark energy in 2010. It will consist of a special 500-megapixel camera installed on the Blanco telescope at the Cerro Tololo Inter-American Observatory, in Chile.

An Advanced Dark Energy Physics Telescope (ADEPT), proposed by Johns Hopkins University (Baltimore, Maryland) and accepted by NASA as a concept proposal, would observe about 1,000 supernovae and about 100 million galaxies. Another one of its proposed goals would be to investigate the million years after the Big Bang, a time that saw the beginning of CMB radiation in the form of that is called baryonic acoustic oscillations, or primordial sound waves.

A proposed Dark Energy Space Telescope, tentatively called Destiny, would look for about 3,000 supernovae and perform measurements of millions of galaxies with the use of (weak) gravitational lensing in order to better understand dark energy. Gravitational lensing is a natural occurrence that happens when a large object is positioned in front of a light source so that when light passes the massive body its mass bends the light around it. The satellite observatory is being proposed by NASA and DoE as a three-year project that would study the structure of matter in the universe. After two years of preliminary study, it might launch around 2013, if finally approved.

Another vehicle to search for dark matter is the proposed Large Synoptic Survey Telescope (LSST) on a mountain peak at Cerro Pachon in Chile. It would be designed to use gravitational lensing in the study of dark energy. The LSST would be able to measure the amount of distortion caused by the massive body onto the light passing around it. 

The Constellation-X Observatory is a dark energy mission that has been proposed by NASA. Located in space, it would consist of four telescopes on a single spacecraft that would be designed to observe gravity around galaxy clusters, and determine how dark energy has affected the clusters’ shapes. It would operate in the X ray region of the electromagnetic radiation spectrum.

The Supernova/Acceleration Probe (SNAP) has been proposed to study three of the before-mentioned dark energy subjects: supernovae, gravitational lensing, and primordial sound waves. Its goal would be to better understand the mechanisms that are making the expansion of the universe accelerate, which many scientists think could be the result of dark energy. The SNAP would measure about 2,000 supernovae each year for three years. Still under proposal, if approved it could be operational by 2013.

The Laser Interferometer Space Antenna (LISA) would be designed to study gravitational waves, and dark energy, by using laser interferometry. Its proposed design would consist of three spacecraft arranged in space in the shape of an equilateral triangle. The three spacecraft, at the three points of the triangle, would be arranged as a giant Michelson interferometer (an optical configuration that splits a beam of light into two different paths, and then bounces the two beams back so they recombine, which produces an interference pattern) so that neighboring satellites are about 3 million miles (5 million kilometers) apart (along the sides of the triangle). As a joint venture of the European Space Agency (ESA) and NASA, if approved, it could begin to study gravitational waves by the year 2015.

Measurements of the rate of expansion of the universe are aggressively being made by astronomers around the world. Consequently, since dark energy is seen as a cause of this acceleration, it is also seen as an important entity to be studied.

How much dark energy there is in the universe, and how much affect it has on the accelerated expansion of the universe may ultimately determine the fate of the universe. Will it end in a Big Rig (where the universe continues to expand and eventually rips itself apart), a Big Crunch (where it contracts back on itself), or another yet-to-be discovered scenario? Who knows?

Cosmologists are studying dark energy, hopefully, to eventually learn the fate of our universe billions of years into the future.

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