New capabilities for Earth Science measurements with 6U CubeSat technologies

Norton, Charles D.; Millar, P. S.; Bauer, Robert A.; Komar, George J.

doi:10.1109/igarss.2016.7730448

Cited by 2 publications

(2 citation statements)

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“…With low size, weight and power (SWAP) and low launch cost, small satellites are appealing for a variety of earth science and defense missions. Advances in sensors and communication hardware have enabled small satellites to produce imagery and other data which rival much larger spacecraft (Norton et al 2016;Alminde et al 2009;Weston et al 2020;Shah and Arshad 2013). Cubesats have also been sent on deep space missions for the first time with the launch of the MarCo spacecraft to Mars in May, 2018 (Tkacenko et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Design of a high-stability heterogeneous clock system for small satellites in LEO

2021

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We describe our investigation into the performance of low-power heterogeneous timing systems for small satellites, using real GPS observables from the GRACE Follow-On mission. Small satellites have become capable platforms for a wide range of commercial, scientific and defense missions, but they are still unable to meet the needs of missions that require precise timing, on the order of a few nanoseconds. Improved low-power onboard clocks would make small satellites a viable option for even more missions, enabling radio aperture interferometry, improved radio occultation measurements, high altitude GPS navigation, and GPS augmentation missions, among others. One approach for providing improved small satellite timekeeping is to combine a heterogeneous group of oscillators, each of which provides the best stability over a different time frame. A hardware architecture that uses a single-crystal oscillator, one or more Chip Scale Atomic Clocks (CSACs) and the reference time from a GPS receiver is presented. The clocks each contribute stability over a subset of timeframes, resulting in excellent overall system stability for timeframes ranging from less than a second to several days. A Kalman filter is used to estimate the long-term errors of the CSACs based on the CSAC-GPS time difference, and the improved CSAC time is used to discipline the crystal oscillator, which provides the high-stability reference clock for the small satellite. Simulations using GRACE-FO observations show time error standard deviations for the system range from 2.3 ns down to 1.3 ns for the clock system, depending on how many CSACs are used. The results provide insight into the timing performance which could be achieved on small LEO spacecraft by a low power timing system.

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Section: Introductionmentioning

confidence: 99%

Design of a high-stability heterogeneous clock system for small satellites in LEO

2021

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“…Advances in sensors and communication hardware have enabled small satellites to produce imagery and other data, which rival products from much larger spacecraft (Ali Shah & Arshad, 2013; Alminde & Laursen, 2009; Bryerton et al., 2016; Chattopadhyay, 2017; Kalemci et al., 2013; Norton et al., 2016; Peral et al., 2015; Segret et al., 2018). Cubesats have also been sent on deep space missions for the first time with the launch of the MarCo spacecraft to Mars in May 2018 (Decrossas et al., 2019; Hodges et al., 2017; Tkacenko et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

A low complexity smoothing algorithm for improved GPS point solutions on board LEO spacecraft

2021

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This paper describes a novel approach for reducing the kinematic position and time errors on a GPS receiver in low Earth orbit. For dual‐frequency GPS receivers, point solution errors are dominated by signal‐in‐space ranging errors, which introduce sharp discontinuities in the position and time estimates when GPS visibility changes. These discontinuities may be calculated and removed, greatly reducing the peaks of the errors, at the expense of introducing a slowly varying bias, which is estimated and removed. The paper gives a detailed description of the algorithm and illustrates its use on a GPS receiver using historical ephemerides. To demonstrate real‐world efficacy, GRACE‐FO observations are processed using the proposed approach. Real‐time results show the reduction of the time error standard deviation by 16% to 1.9ns and the reduction of the 3D RMS error by 17% to 1.06m. Maximum real‐time errors are reduced 26% and 32%, respectively. Delayed processing offers greater reductions of errors, near 40%.

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New capabilities for Earth Science measurements with 6U CubeSat technologies

Cited by 2 publications

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Design of a high-stability heterogeneous clock system for small satellites in LEO

Design of a high-stability heterogeneous clock system for small satellites in LEO

A low complexity smoothing algorithm for improved GPS point solutions on board LEO spacecraft

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