C ubeSat H andling O f M ultisystem P recision T ime T ransfer The CHOMPTT Precision Time Transfer CubeSat Mission Nathan Barnwell, Lucas Bassett-Audain, Paul Buchman, Maria Carrasquilla, Leopoldo Caro, David Keister, Olivia Formoso, Seth Nydam, Blake Richards, Paul Serra, John W. Conklin Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly 1/18
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CubeSat Handling Of Multisystem Precision Time Transfer
The CHOMPTT Precision Time Transfer CubeSat Mission
Nathan Barnwell, Lucas Bassett-Audain, Paul Buchman, Maria Carrasquilla, Leopoldo Caro, David Keister, Olivia Formoso, Seth Nydam, Blake Richards, Paul Serra, John W. Conklin
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly 1/18
Background and Motivation
• Application of precision time transfer to space:
• Satellite navigation systems (∆𝑥 = 𝑐 ∆𝑡)• Beyond LEO
• Global time standards
• Test of general relativity
• Satellite encryption/authentication
• Optical time transfer• More resilient to ionospheric effects
than RF (~1/f2)
• CNES T2L2 (2008), hosted payload on Jason-2
• CHOMPTT objectives:• <200 ps time transfer error (6 cm)
• <20 ns clock drift after 1 orbit (6 m)
• Real time clock update
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly
GPS Constellation Gravity Probe A (1976)
Common View Non-common View
T2L2 mission [P. Guillemot et al 2006]
2/18
Time Transfer
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly
t0 ground
tground
t2ground
tspace
t1space
3/18
Optical Precision Time-transfer Instrument (OPTI)
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly 4/18
OPTI Flight Configuration
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly
5
Interface Board
Support Board
Event Timers
(2×)
CSAC
MAC
Light Collectors
(2×)
Retroreflector
(not shown)
5/18
OPTI Engineering Model
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly
TEC controllers andreverse bias voltage
Interface & power regulator
(High altitude balloon
configuration)
Bottom
(Nadir facing)Top
(Zenith facing)
Event Timers (2×)
CSAC
MAC
Photodiodes (2×)
6/18
Clocks
Nathan Barnwell, 2015 Spring CubeSat Developers’ Workshop, Cal Poly