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Recent developments in space-based gravitational-wave detection.
Due to NASA budget outlook and to the astro2010 decadal rankings, in April 2011 NASA and ESA ended their ten-year-long LISA partnership. As a consequence:
ESA is now developing a redesigned European-only gravitational-wave mission, NGO. A new European science team already completed a science performance study, and an industrial study is currently in progress. ESA will decide next year if NGO will go forward as a Cosmic Vision L-class mission, in which case NASA may participate as a minor partner.
Dr. Tuck Stebbins from NASA GSFC has participated in the European process as an observer and has been reporting his findings to the U.S. science community.
NASA is developing alternative, long-term plans to address LISA science in case ESA does not select NGO. To this end, NASA issued a Request for Information to solicit ideas for gravitational-wave mission concepts at various cost points, and formed a Community Science Team who, together with a Core Team of NASA scientists and engineers, will formulate notional mission concepts for further study.
The results of the studies will be presented in summer 2012 to the NRC Space Studies Board Committee on Astronomy and Astrophysics; recommendations from the Committee will then guide the development of future US gravitational-wave missions. The mission concepts submitted to NASA and the composition of the Community Science Team can be found on the PCOS website.
Gravity is talking. LISA will listen.
The Cosmos sings with many strong gravitational voices, causing ripples
in the fabric of space and time that carry the message of tremendous
astronomical events: the rapid dances of closely orbiting stellar remnants,
the mergers of massive black holes millions of times heavier than the Sun, the
aftermath of the Big Bang. These ripples are the gravitational waves
predicted by Albert Einstein's 1915 general relativity; nearly one
century later, it is now possible to detect them. Gravitational waves will
give us an entirely new way to observe and understand the Universe,
enhancing and complementing the insights of conventional astronomy.
LISA, the Laser Interferometer Space Antenna, is a joint NASA–ESA
mission to observe astrophysical and cosmological sources of gravitational
waves of low frequencies (0.03 mHz to 0.1 Hz, corresponding to oscillation
periods of about 10 hours to 10 seconds). This frequency band contains the
emission from massive black-hole binaries that form after galactic
mergers; the song of compact stellar remnants as they slowly spiral to
their final fate in the black holes at the centers of galaxies; the chorus
of millions of compact binaries in our own Galaxy; and possibly the
faint whispers of waves generated shortly after the Big Bang.
LISA consists of three identical spacecraft flying in a triangular
constellation, with equal arms of 5 million kilometers each. As
gravitational waves from distant sources reach LISA, they warp space-time,
stretching and compressing the triangle. Thus, by precisely monitoring the
separation between the spacecraft, we can measure the waves; and by
studying the shape and timing of the waves we can learn about the nature and
evolution of the systems that emitted them.
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