Bulletin of the American Physical Society
2009 APS April Meeting
Volume 54, Number 4
Saturday–Tuesday, May 2–5, 2009; Denver, Colorado
Session T5: Precision Measurements in Gravity |
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Sponsoring Units: GGR Chair: Peter Bender, University of Colorado at Boulder Room: Governor's Square 15 |
Monday, May 4, 2009 3:30PM - 4:06PM |
T5.00001: Beyond the quantum limit in gravitational wave detectors Invited Speaker: The sensitivity of current and next generation interferometric gravitational wave detectors is limited by the quantum properties of the laser light. The quantum noise can be manipulated to improve the sensitivity of gravitational wave detectors in a variety of ways, one of the most promising being injection of squeezed states of the electromagnetic vacuum field into the output port of the interferometer. I will describe recent progress toward and future prospects for sub-quantum noise limited operation of gravitational wave detectors. [Preview Abstract] |
Monday, May 4, 2009 4:06PM - 4:42PM |
T5.00002: LISA Pathfinder: testing the limits of pure geodesic motion for gravitational wave observation in space Invited Speaker: Placing a gravitational reference test mass in nearly perfect geodesic motion, without any perturbing forces, is a critical problem for space-based gravitational wave detection and for a wide class of precision gravitational measurements. For the Laser Interferometer Space Antenna (LISA), high resolution observation of gravitational radiation from distant coalescing massive black holes will require that the geodesic reference test masses that serve as interferometry end mirrors be in free-fall to within a residual acceleration noise of order femto-m / s$^2$/ $\sqrt{Hz}$ at frequencies near 0.1 mHz. The LISA Pathfinder mission, scheduled for launch by ESA and NASA in 2010, aims to demonstrate geodesic purity for a LISA-like test mass inside a co-orbiting spacecraft at a level approaching this LISA free-fall goal. In this talk, I will discuss the LISA Pathfinder flight experiment and what we have learned, in ground-based preparations for the mission, about the limits of free-fall that are relevant to gravitation wave detection and to other precise small force measurements. [Preview Abstract] |
Monday, May 4, 2009 4:42PM - 5:18PM |
T5.00003: The Gravity Recovery and Climate Experiment (GRACE) -- Measuring Climate Change via Gravity Invited Speaker: The joint NASA/DLR GRACE mission is a pioneering project launched in 2002 to measure large-scale mass redistribution on the Earth through precise satellite-satellite microwave tracking. Using dual frequency K and Ka band microwave carrier phase tracking between the two spacecraft to obtain 5 second Doppler normal points with $\sim $100 nanometer/second precision, and coupled with precision accelerometers on board each spacecraft, mass changes equivalent to 1 cm of water over regions a few hundred km in spatial extent can be mapped each month over the entire Earth. These monthly GRACE mass maps have provided an astonishing amount of previously poorly known (or unknown) aspects of large scale climate related phenomena, including mass loss rates in Greenland, Antarctica, Alaska, Arctic ocean circulation, water storage in major river basins, pan-Arctic river discharge, and much more. In this talk, we will discuss the design challenges and engineering approaches for GRACE, the current state-of-the-art science results, and look at approaches for improved follow-on missions, including the use of laser interferometry closely related to that envisioned for LISA. [Preview Abstract] |
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