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AAWSAP DIRD, High-Frequency Gravitational Wave Communications, April 2010

U.S. Department of War · 2010-04-06 · 57 pages · text from the file's own layer

This Defense Intelligence Reference Document, DIA-08-1004-005, is dated 6 April 2010. The Defense Intelligence Agency's Defense Warning Office prepared it under the Advanced Aerospace Weapon System Applications program. It reviews proposed laboratory generators and detectors for high-frequency gravitational waves. It favors a piezoelectric approach for proof-of-concept tests, IR-excited molecules for an operational transmitter and the Li-Baker detector as the receiver. It estimates about 1.9 million bits per second over 7,000 km through the Earth and discusses timing standards and interplanetary navigation uses.

From the source:Release of 2026-09-18 Incident: 4/6/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD examines whether high-frequency gravitational waves could serve as a communications medium while avoiding the attenuation that limits radio-frequency systems. The report surveys proposed transmitter and detector concepts, argues that gravitational-wave communications could support secure point-to-point links, timing standards, and interplanetary navigation, and gives particular attention to laboratory generator concepts and the Li-Baker detector as possible building blocks for such a system. The document makes clear, however, that the entire concept depends on capabilities that had not been demonstrated in practice, including laboratory-scale generation and reliable detection of usable high-frequency gravitational-wave signals. It is an exploratory systems-oriented review built around a future communications concept.

L3: Highly uns able
due to gravlta 1onal
pull of other planets
LS: Stable. May contain
STEREO AORBIT
(Due
L2
•
UNCLASSIFIED//&OR Oii&ICI0L Ll&li QPIL¥
3.4.1 Propagating Signals From Optical Lattice Clocks for Timing
The 1 part in 10 18 measurement precision of optical lattice clocks will be affected by
general relativity effects, in other words propagation delays due to gravitational field
gradients will be readily measureable. "It will make us think a little harder about what
we really mean by time," Kleppner (2008). In effect, measuring the propagation delays
at this level allows very fine measurement of the "geoids," or surfaces of constant
gravity, surrounding planets and inhabiting interplanetary and interstellar space. The
delay experienced by RF waves could therefore be precisely compared with the
propagation delay experienced by gravitational waves, which are not as strongly
affected by the presence of mass. Such a differential propagation delay comparison
(between RF & GW) could lead to an important new technology in the mapping of
geoids, which could for instance be applied to the problem of mapping the positions of
the Lagrangian points, which vary slightly over time.
3.4.2 In Navigating and Mapping Interplanetary Geoids
The importance of locating and navigating to Lagrangian points is well established
(Baker, 1967). See Figure 23 for a depiction of the Earth's Lagrangian points and their
uses.
Gravity holes
TheEarth and sun's gravitational fields balance at five Lagrangian points, U to LS. Later this year t he STEREO Aand B
spacecraft will explore the L4 and LS regions for the first time
EARTH ORBIT
o reach L4 September 2009)
L4: Stable. May contain
dus and rocks rom the
e.irly solar sys em
L4
Ll: 1.5 million m
rom Earth Ideal location
for monitoring Lh e sun Home
co NASA5 ACE, SOHO and
WINOsatelhtes L2: 1.5 million km from Earth.
Permanently shielded from the
sun Home to NASA'sWMAP
satellite. The Planck satellite,
Herschel and James Webb space
dus and rocks from the elescopes will all sit here
early solar system
(Due to reach LS October 2009)
Figure 23. The Earth's Associated Lagrangian Points (New Scientist, 9Feb09 and Baker ( 1967), p.128, Figure
2.2]
UNCLASSIFIED/ /FOP OiiiilCl.t.k l!ISI!!! l>flti
STEREO BORBIT
31

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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 57 pages are in the text index: search them above, or from the library's search.