Hopkins, Randall

Stahl, H. Philip

NASA Technical Reports Server

Potential Large-Aperture UVOIR Space Observatory enabled by SLS
H. Philip Stahl (h.philip.stahl@nasa.gov) and Randall Hopkins (randall.hopkins@nasa.gov)
SPACE LAUNCH SYSTEM
Launch vehicle mass and volume capacity drives cost because of
the complexity of engineering a large space telescope to fit inside
a 5-meter fairing envelope with a 6.5 mt mass budget.
SLS mass and volume capacities mitigate this cost risk:
• ATLAST-12 is designed to fit in an SLS Block-IIB (scheduled
for 2028) with a 10-m fairing (9.1-m dynamic envelop
diameter) and 45 mt mass capacity to SE-L2.
• 40% margin allows for ‘dry’ payload mass of 27 mt.
SLS is a phased development effort. Block I (scheduled for 2018)
will have a 5-m ‘commercial’ fairing and provide 25 mt to SE-L2.
Block IB (2024) will have an 8.4-m diameter 19-m tall ‘short’
fairing and provide 35 mt to SE-L2. Block II (2026) will have an
8.4-m 27-m ‘long’ fairing and an additional booster segment to
provide ~45 mt to SE-L2. Finally, Block IIB (2028) will have a
10-m x 31-m fairing which can be delivered ~ 45 mt to SE-L2. A
planned advanced booster and composite fairing are expected to
raise this mass to ~55 mt.
MASS
SLS mass capacity enables
fabricating a 12.5-meter class
primary mirror using existing
technology. Allocating 12-mt to
the primary mirror assembly is
only 100 kg/m2. Using existing
65 kg/m2 technology, produces a
8-mt primary mirror.
Analysis indicates that a 4-mt
support structure is stiff enough
to survive launch loads.
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POINTING CONTROL
ATLAST-12 body points the observatory with a stability of < 1
mas for a period of up to 3000 minutes without interruption.
Pointing stability enables exoplanet and UV science. Exoplanet
science requires stability to minimize contrast leakage. UV
science requires stability to maximize throughput by placing the
science object of interest directly onto the entrance slit of the UV
spectrograph without the need of a fine steering mirror. Pointing
duration is also required to enable faint object science.
Pointing is accomplished via the attitude control system,
including: Fine Guidance Sensor; coarse pointing system (gyros,
star-trackers, reaction wheels); and Active Vibration Isolation
system between the spacecraft and observatory.
To enable up to 3000 minutes of continuous observing time,
ATLAST-12 uses solar panels with solar pressure kites on 10 m
deployable booms to balance solar pressure exerted on the scarfed
telescope baffle tube.
• The mass and volume capacity of NASA’s planned Space Launch System (SLS) enables 
potential Large Space Observatories.
• ATLAST-12 mission concept specifically takes advantage of SLS capacities.
  
VOLUME
SLS volume capacity enables a 12.5 meter class primary mirror
using an architecture with fold-forward/fold-aft petals around a
central 6 to 8 meter monolithic mirror.
https://ntrs.nasa.gov/search.jsp?R=20160000708 2019-08-31T04:52:16+00:00Z


Potential Large-Aperture UVOIR Space Observatory Enabled by SLS

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