Transcript A thought experiment (Swift

Low Energy, Low
Cost Swift
A design experiment
June 2010
Mission Statement
To detect and locate low energy X-ray
bursts as precursors for supernova events,
and to examine their time evolvement in the
UV spectrum, using low cost space platform.
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Main Mission Requirements
Source Localization: 0.5°
 Sky coverage: as large as possible.
 Low Cost: (< 20M$)
 Short Response Time: (<0.5 Hr)
 Mission duration: > 5 years
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Mission Concept
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Scan the sky using Wide Field Low Resolution
X-ray Telescope (WFLRXT).
Use onboard processing to identify events,
excluding the milky way, sun and planets.
Upon detection, maneuver and image the event
vicinity using the narrow field UV Telescope.
Combine the two images (UV & X-ray) and
transmit it using satellite phone/internet to
designated destinations.
Alert all Hi-Res narrow FOV telescopes, and
keep imaging using the UV telescope.
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Designated Bus
IMPS* 2 BUS (used by TECSAR & Venμs
satellites).
 Onboard processor: LEON-3
 Power Supply: 800W
 Bus Power Consumption: 250W
 Battery Capacity: 30 Ah
 Bus Dry Mass: 190 Kg
 Payload Mass: ≤150 Kg
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*IMPS = Israeli Multi Purpose Satellite
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BUS – AOCS system
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Actuators:
 4 reaction wheels (1 spare) – fine pointing
 2 X 3 axis magento-torquers– momentum
 Hydrazine Thrusters
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Sensors:
 2 sun-sensors
 2 magneto-meters
 MEMS coarse rate
 GPS Receiver
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unloading
gyro
Propulsion System (for orbit control):
 Hydrazine
Thrusters
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Wide Field X-Ray Payload
FOV: 2 sr (89 x 89 deg)
 PSF: <17 arcmin
 Mass: 20 kg
 Power: 150 W
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*Based on SWIFT – BAT
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Narrow Field UV payload
 Ultra Violet Optical Telescope, 3 deg field
 170 to 650 nm wavelengths*
 30 cm aperture
 500X500 detector (or larger)
 Power: 150 W
 FOV: 3 deg
 Resolution: 0.01 deg
 A/D: 16 bit
*Based on SWIFT – UVOT
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Data Storage and Transmission
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LEON3 On Board Computer (2 GBytes)
 More
than 100 UV images
30 images for the first 30 minutes
 48 images for the next 24 hours
 16 images for the last 24 hours
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TDRSS datalink (10Mbits/sec)
 0.4
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sec for image
Satellite Phone (50 Kbit/sec)
 80
sec for image
*image size: 4Mbits = 500x500@16bit without compression
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Orbit
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Dawn-Dusk sun-synchronous orbit
 Altitude:
700 KM maybe higher to avoid debris
 Inclination: 97 deg
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Orbit Benefits
 Constant
sunlight (no eclipse)
 Constant thermal conditions
 Low radiation
 Similar to commercial earth observation
satellite orbits (Cheaper launch opportunities)
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Imaging Attitude
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Simple solution – Non maneuvering
satellite
 Payload
always facing away from the sun
(Efficiency: 80%)
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Complicated solution - maneuvering
satellite
 Scan
continuously all non-obstructed sky
 Requires secondary wide field UV payload
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On-board Processing
Masking out unwanted regions within the
FOV (i.e. Milky way, sun and planets)
 Merging UV and X-ray images upon
detection
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ROM pricing
Hardware
 Work
 Total Price
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7.5M$
5.0M$
12.5M$
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