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SPIDAR: VLF Astronomy on the Moon

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Title: SPIDAR: VLF Astronomy on the Moon


1
SPIDAR VLF Astronomy on the Moon
  • Jodi Y. Enomoto
  • University of Southern California
  • ASTE 527 Space Exploration Architectures Concept
    Synthesis Studio
  • December 15, 2008

2
Contents
  • Context and Rational
  • VLF Astronomy
  • A New View of the Universe
  • Why do we need the Moon?
  • South Pole Observatories
  • SPIDAR (South Pole Isolated Dipole ARray)
  • Optical Interferometer
  • Heliograph
  • Infrared Interferometer
  • Further Studies Future Missions

3
Context
  • Mission Statement
  • Return humans to the Moon for reliably advancing
    and honing Mars Forward technologies and
    experience.
  • In the process, establish permanent science
    assets with ASAP returns for all of humanity.
  • This presentation mainly focuses on the 2nd
    priority.
  • Astronomers are a large and active Origins and
    lunar science from the Moon community.
  • How to deploy, calibrate and commission a variety
    of science payloads, using crew, as well as their
    preferred locations spread out globally.

4
Rationale
  • Astronomy may not be the reason to go to the
    Moon, but it is definitely something we can do
    that would be beneficial to the scientific
    community and humanity as a whole.

5
VLF Astronomy A New View of the Universe
  • What will we find?
  • New phenomenon, objects…
  • Low frequency SETI?

6
VLF Astronomy Why do we need the Moon?
  • Used as a shield
  • The Sun Solar Wind, Solar Flares, Coronal Mass
    Ejections
  • Large stable platform
  • Interferometers with very long baselines
  • No propellants or thrusters necessary for
    positioning or formation flying

7
Observatory Locations
Future Missions
Observatory
North Pole Observatory Peary Crater
Mid Latitude Observatory Grimaldi Basin (East
Side, View from Earth)
Far Side Observatory Daedalus or Tsiolkovsky
Crater
South Pole Observatories Mons Malapert,
Shackleton Crater, Schrodinger Basin
8
South Pole Observatories
Mons Malapert
Shackleton
Schrodinger
9
Schrodinger Basin SPIDAR Observatory
Transmit to Lunar Base Station
Dipoles
Supporting Cables
Anchors
SPIDAR South Pole Isolated Dipole ARray
Communication Power
5km Diameter
10
SPIDAR Observatory A Curved (Hanging Parabola)
Geometry
Allowing some slack the lines would make it more
feasible to achieve an array with a MUCH longer
baseline
SPIDAR South Pole Isolated Dipole ARray
Communication Power
50km Diameter
ABE Artillery Based Explorer
Dec 15, 2008
SPIDAR
11
Schrodinger Basin SPIDAR Observatory
Dipoles
Supporting Cables
Anchors
Communication Power
5km Diameter
12
Possible Location for SPIDAR Schrodinger Lava
Tube
Dark-Halo Crater on the Floor of Schrödinger
Basin Located at 76S, 139E 5 kilometers
across is a volcanic vent that erupted ash during
the period of mare volcanism on the Moon, more
than 3.5 billion years ago.
http//www.lpi.usra.edu/publications/slidesets/cle
m2nd/slide_4.html
5km
High Resolution
13
Assumptions
  • 14 Lunar surface days.
  • Astronauts will assist emplacement of the array
    on the lunar surface.
  • Rovers, Tele-Operations, etc.
  • Power and communication infrastructure is
    established prior to the observatory
  • Lunar libration is accurately accounted for with
    software algorithms.
  • Diurnal temperature variation considerations.

14
Emplacement of the Array
  • Raytheon TOW (Tube-launched, Optically-tracked,
    Wire-guided) Weapon System Technology
  • Simple, straight forward approach Shoot a line
    across the crater, secure it, and pull the array
    across.
  • Pneumatics and (reusable) spring launchers with
    crossbows.
  • Fine adjustments Use a laser (pointing) system
    to indicate desired emplacement points for the
    array.
  • After the lines are shot across the distance of
    the crater, astronauts can make fine adjustments
    to the final placement.

Dec 15, 2008
SPIDAR
15
Calibration of the Array
  • Inertial Measurement Units and Star Trackers
    (with accurate star maps) to accurately estimate
    the position (orientation and curvature) of the
    array
  • Curve fitting of each line array
  • Interpolate / Extrapolate each element position
  • Using laser range finders to get several accurate
    measurements along each line

Dec 15, 2008
SPIDAR
16
Calibration
  • Inertial Measurement Units and Star Trackers
    (with accurate star maps) to accurately estimate
    the position (orientation and curvature) of the
    array
  • Curve fitting of each line array
  • Interpolate / Extrapolate each element position
  • Using laser range finders to get several accurate
    measurements along each line.

Dec 15, 2008
SPIDAR
17
Mons Malapert Optical Interferometer
  • Meets the objectives and requirements of the 2005
    ESAS report.
  • Location Longitude 0 degrees, latitude 86
    degrees S
  • Continuous LOS to Earth for communications link
    capability
  • Summit is a large, relatively flat landing area
  • 50km in its east-west dimension
  • Optical Interferometer placed on Mons Malapert
  • 3 or more observatories placed 1km or more apart
  • Resolution of milli-arc-seconds to
    micro-arc-seconds

18
Mons Malapert Optical Interferometer
http//www.sciencecodex.com/graphics/Altair_Comp.j
pg
19
Space Interferometry Mission Search for
Extrasolar Planets
http//en.wikipedia.org/wiki/Space_Interferometry_
Mission
20
Shackleton Crater Heliograph Infrared
Interferometer
  • Peak of eternal light ? Heliograph, Solar
    Observation
  • Crater of eternal darkness and extremely low
    temperatures ? Infrared Interferometer
  • ILOA (International Lunar Observatory
    Association) Planning 3 missions to the Moon
  • ILO-X (Precursor)
  • ILO-1 (Polar Mission)
  • ILOAs Human Service Mission
  • Mons Malapert and Shackleton Crater

21
Future Studies…
  • SPIDAR baseline aperture
  • Increased for higher resolution capability
  • Artillery Based Explorers (ABEs) for array
    emplacement (towed lines)
  • Up to 10km (accurate) range
  • Calibration of the array
  • Accuracy requirements
  • Timeline
  • Latest ESAS document specifies 14-day missions
  • Limits the amount of time on the lunar surface to
    4 days

22
Future Missions… A Phased Approach
  • Early Missions
  • Seismic activity study
  • UV, Visible and Infra-red (IR)
  • Future Missions with a Permanent Lunar Base
  • Observation extra-solar planets, environment,
    surface
  • Very long wavelength radio astronomy
  • Giant radio telescopes carved out of existing
    craters on the Moon.
  • Optical Interferometer
  • 3 or more observatories spaced 1km apart.
  • ISRU and Giant Liquid Mirror Telescopes (50m)
  • Spinning lunar regolith in a circular dish to
    create large parabolic surface.
  • Impossible without gravity. However, the Moons
    lower gravity provides the opportunity to achieve
    extremely large scopes.

23
References
  • http//www.iloa.org/media/Moonbase_Mons_Malapert.p
    df
  • http//www.lpi.usra.edu/publications/slidesets/cle
    m2nd/slide_4.html
  • http//web.mit.edu/iang/www/pubs/artillery_05.pdf
  • Takahashi, Yuki D., New Astronomy From the Moon
    A Lunar Based Very Low Frequency Array,
    Department of Physics and Astronomy, University
    of Glasgow, July 2003
  • http//www.sciencecodex.com/graphics/Altair_Comp.j
    pg
  • http//en.wikipedia.org/wiki/Space_Interferometry_
    Mission

24
  • Jodi Y. Enomoto, has 5 years of experience in
    Governmental and Aerospace engineering programs,
    whose interests include attitude determination
    and control systems, digital signal processing,
    and signal processing algorithms for airborne
    radar systems. She has a B.S. degree in EE with
    an emphasis on Control Systems from the
    University of Hawaii, Manoa, and is currently
    pursuing an M.S. degree in EE with an emphasis on
    DSP and Communications at the University of
    Southern California. Her experience related to
    the contents within this document are almost
    entirely limited to the research performed while
    creating this concept in order to fulfill the
    course requirements of ASTE 527 during the Fall
    2008 semester at USC .

Reference
25
Back-up slides
26
  • VLF Astronomy
  • http//www.ugcs.caltech.edu/yukimoon/RALF/
  • We, humans on Earth, have essentially never
    observed the universe at any wavelengths greater
    than 20m (frequencies below 15MHz) because of
    absorption and scattering by the Earths
    ionosphere.Even at 30MHz (10m), ionospheric phase
    effects limit the interferometry baseline to only
    5km, corresponding to only about 10 arcmin
    resolution.Observing through this new spectral
    range will lead to discoveries of new phenomena
    and new classes of objects.

27
Abstract Picture
SPIDAR South Pole Isolated Dipole ARray
Rover Crossbow
28
Schrodinger Basin
  • Low Frequency SETI and Radio Astronomy
  • SPIDAR (South Pole Isolated Dipole ARray)
    Observatory
  • Frequencies lt 20 MHz ? Wavelengths gt 15m
  • High resolution requires huge antenna aperture
  • ILOM (In-situ Lunar Orientation Measurements) and
    LLFAST (Lunar Low Frequency Astronomical
    Observatory) are proposed as plans of
    astronomical observations on the Moon which
    should be realized in a future lunar mission.
    ILOM is a selenodetic mission to study lunar
    rotational dynamics by direct observations of the
    lunar physical libration and the free librations
    from the lunar surface with an accuracy of 1
    millisecond of arc in the post-SELENE project.
    Year-long trajectories of the stars provide
    information on various components of the physical
    librations and we will also try to detect the
    lunar free librations in order to investigate the
    lunar mantle and the liquid core. The PZT on the
    moon is similar to that used for the
    international latitude observations of the Earth
    is applied. The measurement of the rotation of
    the Moon is one of the essential technique to
    obtain the information of the internal structure.
    The highly accurate observation in the very low
    frequency band below about 10 MHz is yet to be
    realized, so that this range is remarkable as one
    of the last frontiers for astronomy. This is
    mainly because that the terrestrial ionosphere
    prevents us from observing the radio waves below
    the ionospheric cutoff frequency on the ground.
    It is, moreover, difficult to observe the faint
    radio waves from planets and celestial objects
    even on the earth's orbit because of the
    interference caused by the solar burst,
    artificial noises and terrestrial aurora
    emissions. The lunar far-side is a suitable site
    for the low frequency astronomical observations,
    because noises from the Earth can always avoided
    and radio waves from the Sun can be shielded
    during the lunar night.

29
Scientific Experiments
  • Early Missions
  • Seismic activity study
  • UV, Visible and Infra-red (IR)
  • Future Missions
  • Observation of extra-solar planets
  • Very long wavelength radio astronomy
  • Giant radio telescopes carved out of existing
    craters on the Moon.
  • Optical Interferometer
  • 3 or more observatories spaced 1km apart.
  • ISRU and Giant Liquid Mirror Telescopes (50m)
  • Spinning lunar regolith in a circular dish to
    create large parabolic surface.
  • Impossible without gravity. However, the Moons
    lower gravity provides the opportunity to achieve
    extremely large scopes.

30
Limitations / Showstoppers
  • Moon-quakes
  • Highly debated. Seismic disturbances were
    measured over the course of 8 years by the Apollo
    missions, showing at most 1 disturbance in a
    given area per year.
  • Lunar dust

31
Effective Aperture Study
  • Effective aperture of a large pseudorandom
    low-frequency dipole array Ellingson,
    S.W. Antennas and Propagation Society
    International Symposium, 2007 IEEE Volume , Issue
    , 9-15 June 2007 Page(s)1501 - 1504 Digital
    Object Identifier   10.1109/APS.2007.4395791 Summa
    ryThe long wavelength array (LWA) is a new
    aperture synthesis radio telescope, now in the
    design phase, that will operate at frequencies
    from about 20 MHz to about 80 MHz.This paper
    describes some preliminary estimates of Ae for
    such an array. This is a non-trivial problem
    because the antennas are strongly coupled and
    interact strongly with the ground. To bound the
    scope of this preliminary investigation, the
    antennas are modeled as thin straight half-wave
    (nearly resonant) dipoles, and we restrict our
    attention to the co-polarized fields in the
    principal planes. First, we consider results for
    a single element in isolation. Next, we consider
    the results for the entire array, which are
    compared to the results for the single element
    and also to the physical aperture of the station.

32
History VLF Array Design Studies 1990s
33
LOFAR Operational Since 2006
http//images.google.com/imgres?imgurlhttp//web.
mit.edu/annualreports/pres02/images/03.05_fig2.jpg
imgrefurlhttp//web.mit.edu/annualreports/pres02
/03.05.htmlusg__b5RH0Z3amUyVzN_Gk58a7JjoGHgh3
54w500sz59hlenstart72um1tbnid2detmLAni
IBN6Mtbnh92tbnw130prev/images3Fq3DLOFAR2
6start3D5426ndsp3D1826um3D126hl3Den26sa3D
N
  • (LOFAR) Low Frequency Array 10-240MHz
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