A 16-m Telescope for the Advanced Technology
Large Aperture Telescope (ATLAST) Mission
National Aeronautics and
Space Administration
Jet Propulsion Laboratory
California Institute of
Technology
ADDITIONAL / OPTIONAL
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Charles F. Lillie, Dean R. Dailey and Ronald S. Polidan
(Northrop Grumman Space Technology)
and the ATLAST Concept Study Team
Abstract
Telescope Performance
17-m
The segmented mirror and deployable optics technologies developed for the
James Webb Space Telescope enable a 6.5 meter diameter telescope to be
folded for launch in the 5-meter diameter Ariane 5 payload fairing, and
deployed autonomously after reaching orbit.
Since Galileo’s first telescope 400 years ago, new technologies have
enabled the development of increasingly large telescopes. JWST’s
segmented, deployable optics enable space telescopes with apertures
larger than their launch vehicle’s fairing diameter, and its chord-fold
architecture provides a simple, roust deployment approach.
Late in the next decade, when the Lunar Program’s Ares V Cargo Launch
Vehicle payload fairing becomes operational, even larger telescope can be
placed in orbit.
HST 2.4-m JWST 6.5-m
In this paper we present our concept for a 16.8-meter JWST derivative,
chord-fold telescope which could be stowed in the 10-m diameter Ares V
fairing, plus a description of the new technologies that enable ATLAST to be
developed at an affordable price.
Key Technologies to Enable the
Next Generation Space Telescopes
ATLAST 8-m
ATLAST 16-m
With 36 mirror segments (2.4-m flat-to-flat) and a maximum tip-to-tip distance
of ~17-m, the ATLAST 16-m telescope has a collecting area ~40 times greater
than Hubble’s (180 m2), angular resolution ~7 times better than Hubble’s (9.4
milli-arcsec at 0.63 microns) and a limiting magnitude (for point sources) ~8.5
magnitudes fainter than Hubble’s.
When combined with the large lift capability and fairing volume of the
Ares V launch vehicle, the new technologies shown below will enable
the ATLAST 16-m telescope to be developed at an affordable cost.
• Rapid, low cost fabrication of ultra-light weight
primary mirror segments
– Eliminates time consuming grinding and polishing
Nonolaminate
on Mandrel
– Several approaches including vapor deposition of
nanolaminates bonded to actuated substrates
• Active figure control of primary mirror segments
– High precision actuators
– Surface parallel actuation eliminates need for stiff
reaction structure (SMD)
Mission Concept
• High speed wavefront sensing and control
Telescope Dimensions
Our ATLAST 16-meter telescope Mission Concept will utilize the
capabilities of the Ares V Cargo Launch Vehicle to place a JWST-derivative
UV-Optical telescope in a halo orbit around the Sun-Earth L2 point in the
post-2020 time frame.
The primary mirror (PM) of the telescope consists of thirty-six 2.4-meter
hexagonal (flat-to-flat). Candidate mirror materials include ULE glass and
SiC, including adaptive mirror segments with replicated nanolaminate mirror
surfaces that are currently under development. The segments are attached to
the three sections of a backing structure with a hexapod of linear actuators
which allow each segment to be placed on the PM’s ideal parabolic surface.
A tripod of tubular struts forms the secondary mirror support structure
(SMSS).
In preparation for launch, the SMSS is folded against the face of the PM
center section, and the PM “wings” fold back against a cylindrical
instrument compartment which is attached to a spacecraft bus which
provides power, attitude control and communications for the telescope and
its instruments. Solar array panels, an antenna and a solar sail are also folded
up against the spacecraft bus, and a sunshade is folded around the instrument
compartment.
After ATLAST reaches orbit and is separated from the launch vehicle, its
solar arrays and high gain antenna will be deployed, and the instrument
compartment will be detached from the spacecraft bus and held by an
articulated “positioning and isolating boom” while the SMSS and PM are
deployed. Following this, a sunshade if erected around the deployed
telescope to provide a light baffle and a thermal enclosure, and a solar sail is
deployed to align the center of (solar radiation) pressure of the deployed
structure with it’s center of mass in order to minimize solar torque effects on
the attitude control system.
“Sugar Scoop”
Stray Light
Baffle
Ares V
Notional
Fairing
– High density figure control enables very light weight
mirror segments
As shown above and in the following figure, when fully deployed the 16-m
telescope has a maximum width of ~19.4-m (~64 feet) and length of 103-m (~338
feet, i.e.: it’s roughly the size of the international space station (~108 x 74 x 45
meters – LWH when completed), but has only ~10% of the station’s mass (45,000
kg). . . which is well within the Ares V lift capability (~69,000 kg to L2).
Providing Integration and test facilities for the 16-m telescope will require some
upgrades to existing facilities, but it testing the telescope and verifying its
performance is not beyond the current state-of-the art.
36, 2.4 Meter Hex Mirror
Petals (3 Ring)
Deployable Stray Light Baffle
2.4 Meter Diameter ISIM Tower
19.4 m
Solar Sail for
Momentum
Balance
Scaled JWST Chord Fold
Technology
The positioning boom has a natural frequency of 0.3 to 1.0 Hz to avoid
transmitting reaction wheel vibrations to the telescope, yet still control the
telescope pointing at a lower (0.02 Hz) rate
The sunshade shown above is one of two mechanically deployed design
concepts being considered, along with an inflatable sunshade design which
offers significant packaging advantages. The spacecraft avionics and
instrument components will be packaged in orbital replaceable units
(ORU)’s to facilitate on-orbit servicing.
Model Sensor
Scene Tracker
Focal Plane
Fine Figure &
Phase Sensor
Imaging FPA
(4096 X 4096
8m pixels)
Beam Footprint at
FPA Plane
• Highly-packageable & scalable deployment
techniques
– Deployment architecture should take advantage of light
weight mirrors
• Active control for light weight structural elements to
supply good stability
– Reduces weight required for vibration and thermal
control
Other technology developments that would facilitate the development
of the 16-m telescope include: sunshade materials and deployment
systems; Attitude Control system components such as active/passive
vibration isolation struts; large reaction wheel; fine pointing/beam
steering mirrors; Integration &Test facilities for large aperture
telescopes; and robotic on-orbit servicing capabilities.
Telescope Positioning and
Isolation Boom
16.8 m
Deployable Solar Array
4.4 Meter Diameter Primary
Central Cylinder Structure
Deployable Solar Sail
Conclusions
• Space telescopes with 16-meter and larger apertures are within
affordable reach by the mid-2020’s
• To achieve this we need to initiate a technology development plan
that thoroughly explores the trade options and identifies and matures
the enabling technology
103 m
Preliminary analysis suggests that 16.8 m will fall well within the Ares V lift capacity
• We need the sustained technology development funding to mature
the technology
• HST servicing missions clearly demonstrated the desirability of onorbit servicing, and further developed NASA’s EVA capabilities
• The Orbital Express robotic servicing mission demonstrated the
feasibility of autonomous rendezvous and docking, fluid transfer,
and equipment replacement.
On-Orbit Servicing
The Hubble servicing missions have clearly demonstrated astronaut’s ability to
repair space systems on orbit and to upgrade them with new technology, thus
extending their operational lifetime and increasing their performance by orders
of magnitude.. As a result, recent congressional legislation directed NASA to
design all future space observatories for on-orbit servicing.
The feasibility of robotic servicing on-orbit has also recently been demonstrated
by DARPA's Orbital Express miss which performed the automated rendezvous
and docking maneuvers, equipment replacement and propellant transfer
activities required for servicing an observatory in an L2 orbit.
16.8 m
Primary
– High speed, active while imaging WFS&C allows for
rapid slew and settle and earth imaging
Image Plane & WFS&C Sensor
• DARPA demonstration
program to advance
technologies for satellite
serving
References
R. Polidan, C. Lillie, G. Segal, D. Dailey, “Large Deployed and
Assembled Space Telescopes”, Astrophysics 2020 Workshop,
November 13-15, 2007 in Baltimore, Maryland
http://www.stsci.edu/institute/conference/astro2020
C. Lillie, D. Dailey, R. Polidan, “Future Deployment Systems and
Very Large Fairings”, Ares V Astronomical Workshop, April 26-27,
2008, Moffett field, CA, http://event.arc.nasa.gov/aresv/
– Rendezvous and Docking
– Fluid Transfer (propellant resupply)
– ORU (orbital replacement unit)
Transfer
C. Lillie, D. Dailey, R. Polidan, “Large Telescopes for Launch with the
Ares V launch Vehicle”, 59th International Astronautical Congress, 29
September to 3 October 2008, Glasgow, Scotland.
http://www.iac2008.co.uk/sitesia.aspx/page/112/node/112/l/en
• General Program
– ~5 years from program award to
end of flight operations
– NGST provided the Fluid
Transfer and Propulsion Systems
for the Boeing/Ball spacecraft
– Class C+ (limited redundancy)
• Servicing ATLAST at L2 or the Earth-Moon L1 point could extend
its operational lifetime and enhance its performance
Self portrait of the two docked
vehicles (ASTRO servicing
vehicle on left; NextSat client/
commodities spacecraft on right)
“Launching Science: Science Opportunities Provided by NASA’s
Constellation System”, Report of the National Research Council’s
Committee on Science Opportunities Enabled by NASA’s
Constellation System, Copyright 2008 by the National Academy of
Sciences.