Cosmic Times

Cosmic Times

Age of the universe:
13.7 billion years
Size of the universe:
94 billion light years

Journey to Cosmos' Dark Heart

Artist conceptions of the 3 possible JDEM missions

Image credit: NASA/Department of Energy

Artist conceptions of the Three possible JDEM missions.

Scientists are working to shed some light on the darkest mystery in the universe: Dark energy.

NASA and the US Department of Energy are considering three concept studies to become their Joint Dark Energy Mission (JDEM). JDEM could launch as early as 2013.

JDEM's goal is to sharpen and double-check the distance measurements to Type 1a supernovae. This information should provide important clues to how fast the universe has expanded during the history of the universe.

Type Ia supernovae are used to determine the distances to other astronomical objects. By observing a large number of these "standard candle" supernovae in galaxies far and near, researchers hope to find out just how quickly those galaxies are flying away from us.

The three concept studies are the Supernova Acceleration Probe (SNAP), the Advanced Dark Energy Physics Telescope (ADEPT), and the Dark Energy Space Telescope (Destiny). Each of these space-based observatories look at the supernova in different ways.

SNAP, would use an optical/infrared telescope with light detectors. These detectors are similar to charge-coupled devices (CCDs) used in digital cameras. With a billion pixels, SNAP's detector is a thousand times stronger than any handheld camera. SNAP would detect around 2,000 Type Ia supernovae each year over a wide range of distances. That's about 200 times more supernovae than are now detected each year.

ADEPT would use a near-infrared telescope to locate 100 million galaxies and 1,000 Type Ia supernovae. These will be compared to the very small temperature differences in the Cosmic Microwave Background. This should reveal how the earliest galaxies match up with the earliest clumps of matter and how dark energy has changed the distribution of matter since then.

Destiny would have a near-infrared telescope designed to detect 3,000 Type Ia supernovae over a two-years. It would also spend a year carefully studying a large area of the sky. This would gather new data on changes in the distribution of matter in the cosmos since the Big Bang. Both parts of Destiny's mission will be ten times more sensitive than similar ground-based instruments. •

A service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA/GSFC