IEEE Aerospace and Electronic Systems Magazine - July 2020 - 23

Davarian et al.
system to transmit data without interrupting the primary
mission. Integration of PAs into the antenna has the potential to improve the overall power efficiency of the telecom
system. As with all active arrays, high cost is a key problem. However, recent advances in SiGe active array technology promise to decisively reduce cost. Moreover, SiGe
phased arrays have also shown promise for new 5G mobile
communications systems, which could lead to high volume
production commercial active arrays that could be adapted
for low cost space telecom applications.

SUMMARY AND CONCLUSIONS: STUDY FINDINGS ON
SMALLSAT DTE LINKS AND TELECOMMUNICATIONS
EQUIPMENT
The above study takeaways and findings are summarized
in eight recommendations that can be used by NASA,
other space agencies, and the deep space SmallSat community to improve the performance of SmallSat communications in deep space. These recommendations are
provided below.
1. SmallSats are encouraged to baseline their downlink
at Ka-band to benefit from more spectrum availability,
less competition for spectrum and increased antenna
gain at Ka frequencies relative to lower bands.
2. A study needs to be performed to investigate
options for emergency mode communications. This
might include evaluating the use of directional
antennas, diversity antennas, lower data rates, etc.
3. DSOC has the potential of providing many benefits for
large primary missions that produce volumes of science
data. However, because at this point the technology is
not developed far enough and that a low-cost optical
ground structure does not yet exist, it is recommended
that the planetary SmallSat community continue the
evaluation of this technology for further maturation.
4. A study should be conducted to reduce SWaP of
radios to free up SmallSat resources to be applied to
primary mission goals. The study should include
both DTE and proximity applications. This article
suggests approaches for radio SWaP reduction (see
the "Radios for SmallSats" section).
5. SmallSats that use range observations for their navigation should employ PN regenerative ranging in
accordance with the technique discussed in this article (see the "Range and Delta Differential One-Way
Range" section) to improve range SNR and reduce
interference effect on the range signal, improving
communications efficiency.

JULY 2020

6. SmallSats that intend to use DDOR for navigation
should spread their DOR tone in accordance with
the technique discussed in this article (see the
"Range and Delta Differential One-Way Range"
section) in order to improve their navigation accuracy without added operational cost;
7. Because efficient, powerful SSPAs are needed to
increase the range and DTE rate of SmallSats,
investment should be made in Ka-band SSPAs with
at least 40% power efficiency and an RF output
exceeding 10 W. Similarly, at X-band SSPAs are
needed with at least 40% power efficiency and
larger than 15 W RF output; and
8. Make investments in large aperture CubeSat
deployable antennas focusing on two areas: 1) productize and improve reliability of the new technologies, such as mesh reflector and folded panel
reflectarrays that have been developed in the past
three years, and 2) fund R&D on higher risk new
technologies that have better stowage efficiency/
compaction ratio and/or lower mass density.

ACKNOWLEDGMENTS
The research described in this article was performed at the
Jet Propulsion Laboratory, California Institute of Technology, under contract with the NASA.
The authors would like to thank the valuable inputs
received from A. Biswas and D. Morabito of JPL, and P.
Kinman of California State University, Fresno. They
would also like to thank Government sponsorship.

REFERENCES
[1] D. D. Morabito, "Deep-space Ka-band flight experience,"
Interplanetary Netw. Prog. Rep., Rep. 42-211, 2017.
[2] M. Pugh et al., "The universal space transponder: A next
generation software defined radio," in Proc. IEEE Aerosp.
Conf., 2017, pp. 1-14.
[3] C. B. Haskins et al., "The frontier software-defined radio
for the solar probe plus mission," in Proc. IEEE Aerosp.
Conf., 2016, pp. 1-11.
[4] M. B. O'Neill et al., "Advances in deep space radios," in
Proc. IEEE MTT-S Int. Microw. Symp., 2017, pp. 398-401.
[5] NASA Laser Communication System Sets Record With
Data Transmissions to and From Moon, Oct. 22, May 22,
2013. [Online]. Available: https://www.nasa.gov/press/
2013/october/nasa-laser-communication-system-sets-recordwith-data-transmissions-to-and-from/#.UmgcTqzhP5x
[6] T. S. Rose et al., "Optical communications downlink from

IEEE A&E SYSTEMS MAGAZINE

a 1.5 U CubeSat: OCSD program (Conference Presentation)," Free-Space Laser Commun. XXXI, vol. 10910,
2019, Art. no. 109100T.

https://www.nasa.gov/press/2013/october/nasa-laser-communication-system-sets-record-with-data-transmissions-to-and-from/#.UmgcTqzhP5x https://www.nasa.gov/press/2013/october/nasa-laser-communication-system-sets-record-with-data-transmissions-to-and-from/#.UmgcTqzhP5x https://www.nasa.gov/press/2013/october/nasa-laser-communication-system-sets-record-with-data-transmissions-to-and-from/#.UmgcTqzhP5x

IEEE Aerospace and Electronic Systems Magazine - July 2020

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