Mission Description——Continued
Introduction | Mission Description | All About Gravitational Waves | Mission Benefits
LISA will operate 50 million kilometers (about 30 million miles) above Earth. The center of LISA's triangle will follow Earth's orbit around the Sun, trailing 20 degrees behind. It will maintain a distance of 1 AU (astronomical unit) from the Sun, the average distance between the Earth and the Sun. LISA's operational position was chosen as a compromise between the need to minimize the effects on the spacecraft of changes in the Earth's gravitational field and the need to be close enough to the Earth for easy communication.
Individually, each spacecraft will travel in its own specially selected orbit, chosen to minimize the changes in the distances between the spacecraft. This distance, LISA's interferometer arm length, will allow observation in the frequency band of most of the interesting sources.
 |
LISA will be complemented by ground detectors.
|
LISA will search for gravitational waves at low frequencies that ground-based detectors can't achieve. However, ground detectors, such as the Laser Interferometry Gravitational-Wave Observatory (LIGO) or VIRGO, and LISA will complement each other. In space, LISA will "hear" the long, low rumble of space-time swells. On Earth, LIGO and others will "hear" higher-frequency space-time ripples. LISA will observe binaries thousands of years before they collide. Ground detectors will observe other binaries just before they collide, when their orbiting speeds are much higher. Both types of observatories are needed to hear the broad spectrum of ripples in space-time.
LISA will detect gravitational wave sources from all directions in the sky. These sources will include all the thousands of compact binary systems——many containing neutron stars, black holes, or white dwarfs——in our own Galaxy, plus merging supermassive black holes in distant galaxies. During the five-year lifetime of the mission, LISA is expected to yield 163 gigabytes of significant data for analysis.
On to About Gravitational Waves
|
