Rotation measurements of a 6U payload dispensed in reduced

Rotation measurements of a 6U payload
dispensed in reduced gravity environment
4th International Workshops on LunarCubes
Sunnyvale, CA
By Floyd Azure, Ryan Hevner, and Walter Holemans (Presenting)
Planetary Systems Corporation (PSC)
2303 Kansas Avenue
Silver Spring, MD 20910
301 495 0737
08 October 2014
Walter, Floyd and Ryan
Ellington Field, TX
August 2014
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 1
Overview
•
Objective
– Measure rotation rates of 6U payloads as a function of dispensing
•
PSC engineers completed four days of flight testing the CSDs
–
–
–
–
•
160 parabolas total
4 days
40 parabolas per day
One every 2 minutes
Ellington Field, TX / Gulf of Mexico
– August 2014
•
Sponsored by PSC, NASA and AFRL
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 2
What is a Canisterized Satellite Dispenser
(CSD)?
•
A box that holds a spacecraft for launch and dispenses on orbit
6U size CSD
6U size Payload
(Spacecraft, like
LWaDi)
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 3
Why are rotation rates important?
•
If payloads are rotating too fast, they’ll consume valuable mission time slowing
down
– Some missions must have low tip-off rates <10deg/sec/axis
• They need to start missions in hours or days
– Some attitude control sensors saturate at high rotation rates (>100deg sec)
•
Other dispensers produce high tip-off rates (>600 deg/sec)
Ref. 1
33 deg/sec
tip-off rate
As dispensed tip-off rate
(>600 deg/sec}
It took ~500 days to
spin down and start
the mission
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 4
Ref. 2
Test Equipment--frame
DC-9
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
After Dispensing
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 5
Test Equipment—Payload “Spacecraft”
•
Solid state sensors (IMU) acquire acceleration and rotation rates about X, Y, Z
– In CSD/frame and dispensing payload
•
Cameras record motion
IMU, data logger
and battery on 6U,
10 kg payload
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 6
Results
•
•
Completed 136 initiations in weightless configuration
No hang fires
– always fully dispensed when commanded
•
•
No uncommanded dispensing
3U and 6U CSD
– Varying
• Ejection spring quantity
• Dispensed mass
• Pre-dispensing rotation rates
– Sometimes rates were intentionally high (~15deg/sec)
• Gravity
– Zero to asteroid gravity
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 7
Video excerpts
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 8
Time History
Rotation Rates (IMU Coordinates)
90
80
70
Micro Gravity
60
50
40
Airplane Descent
Airplane Ascent
Re-installing Payload
30
20
Payload_X
10
Payload_Y
Payload_Z
0
CSD_X
-10
CSD_Y
-20
CSD_Z
-30
Airplane Reaches
Peak Elevation
-40
Separation
CSD Initiation
-50
-60
-70
-80
-90
0.000
08 October 2014
5.000
10.000
15.000
20.000
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
25.000
30.000
Time [Sec]
35.000
40.000
Rotation measurements of a 6U payload dispensed in reduced gravity environment
45.000
50.000
www.planetarysystemscorp.com
Page 9
55.000
Rotation Summary
•
•
•
•
Higher initial rates
produce higher
rates after
dispensing
CSD dispenses
payloads one to
two orders of
magnitude lower
rotation rate than
other dispensers
CSD reliably
dispenses when
initial rates are 10x
higher than typical
of on orbit
Center of mass
off-sets in test
equipment may be
increasing rates
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 10
Test Improvements
•
Add active attitude control to frame so pre-dispensing rates <<1.0 deg/sec
– Like on launch vehicles
•
•
Add deployables that deploy as a function of dispensing
Balance test equipment
– Minimize CM offsets which may increase measured rotation rates
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 11
References
1.
2.
3.
4.
Stefano Rossi, Anton Ivanov, Muriel Richard, Volker Gass, Amin Roesch, Four years
(almost) of SwissCube operations SwissCube Team, Swiss Space Center, Small
Sat pre-Conference Workshop, Logan UT, August 10, 2013
NanoRacks CubeSat Deployer Program-1 releasing satellites from the ISS,
https://www.youtube.com/watch?v=JQy9EwMrILI, 05 March 2014
Azure, Floyd. 2002655A AS RUN SBIR 3U CSD Micro-g Test Plan, PSC, Silver
Spring MD, Sept 2014
Hevner, Ryan CANISTERIZED SATELLITE DISPENSER (CSD) DATA SHEET, PSC,
Silver Spring MD, 21 July 2014
08 October 2014
4th International Workshops on LunarCubes (LCW 4) Sunnyvale, CA
Rotation measurements of a 6U payload dispensed in reduced gravity environment
www.planetarysystemscorp.com
Page 12

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