IEEE Aerospace and Electronic Systems Magazine

48 Pages·2020·24.106 MB·English

This Month’s Covers….
Front Cover: DSN Australian complex; Credit: NASA.
Back Cover: Mars Helicopter, Credit: NASA.
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Editor-in-Chief–PeterWillett
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ContributingEditors
August2020 ISSN0885-8985 Volume35Number8
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BookReviewsEditor–SamuelShapero COLUMN
Conferences–MichaelBraasch
DistinguishedLecturers&
Tutorials–LorenzoLoMonte InThisIssue–Technically................................................... 3
Education–LorenzoLoMonte
History–HughGriffiths FEATURE ARTICLE
StudentResearch–FedericoLombardi
TechnicalPanels–GeorgeSchmidt
Tutorials–W.DaleBlair ImprovingSmallSatelliteCommunicationsandTrackinginDeepSpace—A
WebsiteUpdates–JudyScharmann ReviewoftheExistingSystemsandTechnologiesWith
RecommendationsforImprovement.PartIII:TheDeepSpaceNetwork
AssociateEditorsandAreasof
F.Davarian,D.Abraham,J.Baker,J.Gao,N.Lay,J.Stuart,M.Angert....... 4
Specialty
ScottBawden–EnergyConversion MultibistaticRadarforSpaceSurveillanceandTracking
Systems D.Cataldo,L.Gentile,S.Ghio,E.Giusti,S.Tomei,M.Martorella .......... 14
ErikBlasch,RobertoSabatini–
AvionicsSystems SlipRingTestAssemblyWithIncreasedBreakdownVoltageLimit
DietrichFraenken–Fusionand
forHigh-VoltageBusSatellites
SignalProcessing
F.Avino,B.Gaffinet,D.Bommottet,A.Howling,I.Furno................... 32
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MauroDeSanctis–SignalProcessing
StudentHighlight:EmbeddedSystemforPrecisionPositioning,Detection,
andCommunications
andAvoidance(PODA)forSmallUAS
JasonGross–Navigation,Positioning
GiancarmineFasano–Unmanned G.Ariante ............................................................... 38
AircraftSystems
DanielO’Hagan–RadarSystems NEWS AND INFORMATION
RichardLinares–SpaceSystems
HaiyingLiu–ControlandRobotic
Systems AESSSeniorMembersElevatedin2020 .................................... 2
MichaelCardinale–Electro-Opticand
InfraredSystems,ImageProcessing IEEEAerospace&ElectronicSystemsSocietyOrganization2020 ........ 31
RuhaiWang–SystemsEngineering
2020Aerospace&ElectronicsSystemsSocietyDistinguishedLecturers .. 37
HowtoReachUs
Obituary:ProfessorViktorChernyak
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February 2020 April 2020

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Renato Borges Shobha Ram
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Volodymyr Ulanskyi
Dated: August 2020
In This Issue –Technically
IMPROVING SMALL SATELLITE COMMUNICATIONS AND TRACKING IN DEEP SPACE—A
REVIEW OF THE EXISTING SYSTEMS AND TECHNOLOGIES WITH RECOMMENDATIONS FOR
IMPROVEMENT. PART III: THE DEEP SPACE NETWORK
Thisarticleisthethirdofathree-partseriesinwhichwepresenttheresultsofastudyexploringconceptsfor-
improving communications and tracking capabilities of deep space SmallSats. In Part I, we discussed
SmallSatdirect-to-EarthlinksaswellasSmallSatcommunicationsequipment,andprovidedrecommenda-
tionsforfuturework.InPartII,wefocusedonSmallSatnavigationoptions,disruptiontolerantnetworking,
proximitylinks,andtheuseofthecommunicationlinkforscienceobservations.InPartIII,wefocuson
ground support of deep space SmallSats. We present a brief overview of NASA’s deep space network
(DSN)alongwithconceptsforadaptingtheDSNtoimprovesupportforSmallSats.Wediscussapproaches
for increasing the DSN’s efficiency in handling the anticipated increase in SmallSat communications,
suchasreducingsetupandteardowntimesforacommunicationspass,andreducingDSNtimeallocatedto
Dopplerandrangemeasurements.Anewdemandaccessoperationalparadigmisproposed,whichismore
consistent with SmallSat communications requirements and will facilitate the DSN handling of larger
numbers of spacecraft. Finally, we present the conclusion of the study as a list of recommendations to
improveSmallSatcommunicationsandtracking.
MULTIBISTATIC RADAR FOR SPACE SURVEILLANCE AND TRACKING
Theeverincreasinglyresidentspaceobjectdensityposesachallengeforcurrentandfuturespacemissions
andassets.SpacedebrisinlowEarthorbit(LEO)areofparticularinterestbecausetheyarepresentinthe
highestconcentrationwithrespecttotheotherorbits.Radiofrequencysystems,andparticularlyradar,prove
tobesuitableanswerstotheneedofobservingspaceobject,especiallyatLEO.Thereasonsbehindthis
statementareintheabilityofRFsensorstooperateindependentlyofilluminationandweatherconditions.
Radiotelescopesarepresentinarelativelylargenumberandarewidelyusedforspaceobservation.They
havelargeantennagainandhighlysensitivereceivers,whichmakethemactasperfectreceiversforbistatic
radarsystems.Thisarticlewillpresentthearchitecture,system,andsignalprocessingaspectsrelatedtoa
radar/telescopeRFsystemforspacesurveillanceandtrackingapplications.
SLIP RING TEST ASSEMBLY WITH INCREASED BREAKDOWN VOLTAGE LIMIT FOR
HIGH-VOLTAGE BUS SATELLITES
In this article, a setup including a passive gas breakdown mitigation technique for satellite slip ring
assemblies(SRAs)isintroducedandtested.Thesetupfeaturesacentralconductingring,separatedfromtwo
externalconductinglimitingdiscs(LDs)byinsulatingrings.Thecharacteristicbreakdowncurvesaremea-
suredasafunctionofthesurroundingpressurebybiasingthecentralringandsettingtheLDsatavariable
voltage.Theminimumbreakdownvoltageisincreasedfrom(cid:1)420to(cid:1)860VbybiasingtheLDsatonehalf
ofthevoltageappliedtothecentralring.Thissolutionisfurtherappliedonatest-SRAthatincludesthe
mainfeaturesofastandardcylindricalSRA:astackofconductingringsonwhichconductingbrushesslipto
ensuretheelectricalcontactbetweenmovingcomponents.Theminimumofthebreakdowncurveisraised
from(cid:1)400VforthegroundedLDsto(cid:1)600VforthepassivelybiasedLDs.Thisresultconfirmsthepossi-
bilitytoimproveSRAprotectionfortheentirepressurerangeencounteredbyasatelliteduringitsopera-
tional life, from atmospheric pressure to in-orbit high-vacuum, meeting the requirements for the next
generationofsatellites.
AUGUST2020 IEEEA&ESYSTEMSMAGAZINE 3
FeatureArticle:
DOI.No.10.1109/MAES.2020.2992211
Improving Small Satellite Communications and
Tracking in Deep Space—A Review of the Existing
Systems and Technologies With Recommendations
for Improvement. Part III: The Deep Space Network
FaramazDavarian,DouglasAbraham,JohnBaker,JayGao,NormanLay,
JeffreyStuart, JetPropulsionLaboratory,CaliforniaInstituteofTechnology
MattAngert,AppliedPhysicsLaboratory
INTRODUCTION radioequipment,solidstatepoweramplifiers,antennas,and
operationalconsiderations.
Motivated by the recent interest in employing SmallSats PartIIextendsthediscussiontoothersubjectsofinterest,
for deep space and interplanetary scientific research, this includingspacecrafttrackingandnavigation(radioandopti-
articleinvestigatesthestate-of-the-artintheimplementa- cal),disruption-tolerantnetworking,andproximitylinksand
tion and operation of deep space SmallSat communica- protocols.Equipmentusedforproximitylinks,suchasradios
tionsandtrackingsystemsandproposesimprovementsto andantennas,arealsodiscussed.Additionally,weprovidea
them.Weprovidesurveys,analyses,andexamplesofmis- discussion on the use of SmallSat communication links to
sions, existing or under development, to support our rec-
performradiosciencemeasurements.Finally,wemakerec-
ommendations. The article includes surveys of SmallSat
ommendationstoimprovetheperformanceofcommunica-
communicationequipmentandoperationalstrategies.We
tionandtrackingsystemsofSmallSatsindeepspace.
investigate the shortcomings of the existing systems and
Thissectionoftheseries,PartIII,focuses onground
operationalproceduresandproposerecommendationsfor
support, which is provided by the DSN. The number of
improvements.OurobjectiveistoallowSmallSatstoplay
SmallSats is expected to grow faster than other users of
a greater role in deep space exploration by reducing the
the DSN. In order to continue serving the Deep Space
disparity between the communication systems of larger,
exploration community efficiently and without interrup-
moreexpensivemissions,andSmallSats.
tion, improvements in SmallSat communication systems
Thedirect-to-EarthlinkwasinvestigatedinPartI,along
arenecessarytoavoidnetworkcongestion.
with recommendations to improve the link between space-
DSNmanagementhasdevelopedastrategytomeetthe
craftandground.Amongthetopicswediscussedareradio
communications,opticalcommunications,spacecraftemer- anticipatedincreaseindemandforitsservicesbyimproving
gency communications, the size, power, and mass of the the operational efficacy of the network. This includes the
introductionofon-demandaccessandopportunisticaccessto
theDSN.Theyarealsoinvestigatingotherpotentialenhance-
Thisarticleisthethird inathree-partseries.PartsIandII
ments,suchasthereductionofnetworkloadingbysubsam-
can be accessed in the July 2020 issue of A&E Systems
pling radiometric measurements and a greater SmallSat
Magazine.
missionrelianceonone-waytracking.
Authors’current addresses: Faramaz Davarian,
DouglasAbraham,JohnBaker,JayGao,NormanLay,
andJeffreyStuart,JetPropulsionLaboratory,California
DEEP SPACE NETWORK AND SMALLSATS
InstituteofTechnology,Pasadena,CA91109,USA
(email:[email protected]).MattAngert,Applied
TheDSNprovidesmultipleservicestospacecraft.Thekey
PhysicsLaboratory,Laurel,MD20723,USA.
services are telemetry (data transmitted by spacecraft),
Manuscript received December 1, 2019, revised April
21,2020,andreadyforpublicationMay1,2020. command(datasenttospacecraft),andtracking(Doppler,
ReviewhandledbyRichardLinares. ranging, and delta-differential one-way ranging measure-
0885-8985/20/$26.00(cid:1)2020IEEE ments). Additionally, the DSN is used for radio science,
4 IEEEA&ESYSTEMSMAGAZINE AUGUST2020
Credit:ArtworkbyHenkPander
radio astronomy, very long baseline interferometry, and transmitters,eachonebeing equippedwith a20-kWhigh-
solar systemRADAR. Berner [1] providedmoreinforma- power amplifier at X-band. Moreover, at the Goldstone
tiononDSNservicesandcapabilities. complex,oneofthe34-mantennascantransmit80kW.
The DSN serves missions through its three main deep ThecombinationoftheabovefeaturesallowstheDSN
spacecommunicationscomplexes,atGoldstone,CA,USA; to serve the communication and tracking needs of space-
Madrid, Spain; and Canberra, Australia. These complexes craftthroughoutthesolarsystem.TheDSNhassuccessfully
arestrategicallyplacedtoprovidenearfull-skycoveragefor tracked and communicated with spacecraft at the edge of
spacecraft in deep space (see Figure 1). As Earth rotates thesolarsystem.TheVoyager1spacecraft,whichiscur-
about its axis, service to a spacecraft can be handed over rently exploring the interstellar medium, continues to
from one complex to the next to provide near-continuous, receive support from the DSN [2]. Currently, the DSN
two-way communications. Furthermore, because of their supports close to 40 different spacecraft. Each complex
largesignalcollectionareas(>900m2forthe34-mantennas consists of one 70-m diameter antenna, three or more
and>3800m2forthe70-mantennas)andtheuseofcryo- 34-m diameter antennas, and a signal processing cen-
genically cooled low-noise amplifiers, DSN antennas are ter. Data sent from the DSN to spacecraft, or received
very sensitive. These antennas also function as powerful by the DSN from spacecraft, flow through the Network
Figure1.
DSNantennadistribution(figureborrowedfrom[1]).
AUGUST2020 IEEEA&ESYSTEMSMAGAZINE 5
ImprovingSmallSatelliteCommunicationsandTrackinginDeepSpace—AReviewoftheExistingSystemsandTechnologies...
Figure2.
MissionDataFlow:TheusercommunicateswithitsspaceassetusingaDSNantenna(orantennasifarrayingisused).Dataaresent
to and received from spacecraft. Received data traffic is routed through the complex signal processing center to JPL and eventually
totheuser.
Operations Control Center (NOCC), located at the Jet Therestofthisarticleaddressesimprovementstothe
Propulsion Laboratory in Pasadena, CA, USA. Figure 2 DSNaswellasthespacecrafttoincreasecommunications
shows a conceptual diagram of data flow through the andtrackingcapabilityfordeepspaceSmallSats.
NOCC and the DSN.
TheDSNantennasoperateinseveralfrequencybands
as shown in Table 1. This article only considers deep
INCREASING GROUND ANTENNA OPERATIONS
spaceX-andKa-bands.
The DSN is increasing its inventory of available EFFICIENCY
assets.Inadditiontoaddingantennasatitsthreestandard
complexes, it is also working to expand its cross-support Because currently the DSN has to reliably serve about
agreements with other agencies and nonprofit entities 40 deep space probes with its limited resources, there is
operating medium-to-large communications antennas [3]. alwaysgreatdemandontheDSNantennas.Withthepos-
One example of this is the 21-m antenna at Morehead sibilityofalargenumberofSmallSatscompetingforthe
StateUniversity,Kentucky,USA,thatisbeingintegrated DSN service in future, this situation will become more
intothenetworkwiththeintentionofusingitprimarilyto challenging. Therefore, it is imperative that DSN resour-
serviceSmallSats[4]. cesareusedwiselyandefficiently.
Table1.
FrequencyBandsSupportedbytheDSN(MHz)C,(cid:2)
Band CategoryBBands(distanceto Downlink CategoryABands(distanceto Downlink
Designation Earthgreaterthan2millionkm (Spaceto Earthlessthan2millionkm (Spaceto
Uplink(EarthtoSpace) Earth) Uplink(EarthtoSpace) Earth)
S 2110–2120 2290–2300 2025–2110 2200–2290
X 7145–7190 8400–8450 7190–7235 8450–8500
K — — — 25500–27000
Ka 34200–34700 31800–32300 — —
CTheDSNisinvestigatingthepossibilityofaddinga22-GHzuplinkcapabilityforCategoryAmissions.
(cid:2)FrequencyrangeshavebeenallocatedbytheITUforuseindeepspaceandnear-Earthresearch.
6 IEEEA&ESYSTEMSMAGAZINE AUGUST2020
Davarianetal.
Figure3.
OMSPAisoneofseveralDSNinitiativesforincreasingtheutilizationefficiencyofexistingantennas.Theseinitiativesfocusonbeam-shar-
ingamongstmultiplespacecraftincommonviewofasinglegroundantenna(figureborrowedfrom[6]).
The DSN provides shared beam operations that allow torecoverthedata.Figure3illustratestheOMSPAconcept.
multiplespacecraftdownlinks,improvingantennaavailabil- Figure4(a)isaconceptualillustrationofaMSPA/OMSPA
ityforusers[5].Theconceptofantennasharingbymultiple scenariowithfourprimarymissionsusingtheantennainthe
satellites is known as multiple spacecraft per antenna MSPA format, while five SmallSats opportunistically use
(MSPA). Whenmultiple spacecraftare going tobe within the same antenna to send data down to Earth. Figure 4(b)
thebeamofaDSNantenna,theycanbescheduledtosimul- showshowtheavailablespectrumissharedwhenatotalof
taneouslysharetheantennasuchthattheirtransmissionswill nine spacecraft concurrently use the same antenna. In this
allcomedownthroughtheaperturetoindividuallyassigned example,notalltheavailablebandwidthisused,sothereis
receivers.AgoodexampleofMSPAoperationcanbeseen spectrumavailableformoreSmallSatstoopportunistically
atMars,wheremultiplespacecraftorbitingtheplanetshare accesstheantenna.
thesamegroundantennafortransmittingdatatoEarth.Asof While OMSPA would involve higher latency in data
thiswriting,themaximumnumberofsatellitesthatcanoper- recoverythanatraditionalMSPAdownlink,itcouldstillbe
ateconcurrentlysharinganantennaisfour,althoughthepos- useful for obtaining routine sciencedownlinkonantennas
sibility of increasing the numberof signalsbeyond four is thatmightotherwisebeunavailableduetoschedulingcon-
beinginvestigated. flicts.SincetheSmallSatswouldbeusinganalreadysched-
A recent initiative known as opportunistic MSPA uled antenna beam, they would not, themselves, have to
(OMSPA)allowsfortheantennatobesharedopportunisti- scheduletheantennaandwouldnotcompetewithanyofthe
cally,sothataSmallSatcantakeadvantageofanantenna scheduledmissionsforantennatime.OpportunisticMSPA
thathasbeenscheduledtoprovideservicetoanothermission wouldtend toworkbest in high-activity regionsof space,
(ormissionsincaseofMSPA).Sincetheuseremploysan wheretheprobabilityofbeinginbeamwithanotherspace-
antenna without being scheduled for service, the network craft for a protracted period of time is relatively high. A
willnotassignatraditionalreceivertoobtainthedownlink goodexampleofthisisatMars,wherealloftheorbitingand
signal.Inthiscase,thenetworkprovideswidebandrecorders landedspacecraftarealmostalwayswithinthebeamwidth
(AKAopenloop1receivers)tobeusedwithoutanadvance of a single DSN antenna. The same is generally true at
schedule.Therefore,thesignaltransmittedbytheopportu- Venus,oratanyotherdestinationfurtheroutthanVenusor
nistic user is recorded on the ground using a wideband Mars. OMSPA also applies to spacecraft simultaneously
recorder[6].Hence,thesignalofsuchausermustbeproc- deployingfromupperstagesofalaunchvehicleorspace-
essed later (non-real-time) to extract the transmitted data craftlocatedtogetherintightclustersorconstellations.
frames. The opportunistic use of a ground antenna while Unlike the downlink, there is not a technique for
withinthebeamoccurswhentheuser’sspacecraftsensesthe simultaneously sharing the uplink for MSPA passes. As
presence of a DSN ground antenna beam that has been was pointed out in Part II of this publication, the widely
scheduled for a different mission and begins transmitting. used approach for navigating spacecraft in deep space is
Thesetransmissionsgetcapturedonthewidebandrecorder. through collecting radiometric data types of Doppler,
EachSmallSat’stimeandfrequency-relevantportionofthe range, and delta differential one-way ranging. Doppler
recordingcanthenberetrieved,demodulated,anddecoded and Range are collected using two-way coherent signal-
ing,wheretheuplinkisreturnedcoherentlytoallowsig-
1Openloopmeansthesignaliscapturedbyareceiverthatrecords nalphasedelaymeasurementsontheground.Becausethe
thesignaltobeprocessedlater. uplink cannot be shared among the users of an MSPA
AUGUST2020 IEEEA&ESYSTEMSMAGAZINE 7
ImprovingSmallSatelliteCommunicationsandTrackinginDeepSpace—AReviewoftheExistingSystemsandTechnologies...
Figure4.
(a) Five SmallSats are opportunistically sharing the antenna while four primary missions are using the same antenna. (b) Available
bandwidthisdividedbetweenfourprimarymissionsandfiveSmallSats.Inthisillustration,satellitessharingtheantennaoccupydifferent
amountsofspectrumwithsomeusingmorebandwidththantheothers.
group, the uplink can be allocated to only one user at a ranging(TR),thatsubstitutesthetelemetrysignalforthe
time. Consequently, in MSPA scenarios, the uplink is returned range signal, eliminating the need to transmit
sharedinaserialfashionamongspacecraft. Nonetheless, ranging signals from spacecraft [8]. Since this technique
themorespacecraftparticipateinagivenMSPAscenario, does not transmit ranging signals, telemetry and ranging
the less uplink time is available, on average, per space- canoccursimultaneously–onlyuplinkrangingsignalsare
craft. A new approach to allow multiple in-beam space- necessary. Thus, telemetry signal-to-noise ratio improves
crafttosimultaneouslyuplinkiscurrentlyunderstudy[7]. and potential interference between telemetry and the
The multiple uplinks per antenna (MUPA) technique ranging signal is avoided. With telemetry ranging, it is
involvestime-multiplexingthecommandstreamstomul- also possible to make range measurements without the
tiple spacecraft on the same uplink frequency. However, need for the downlink carrier to be coherently related to
thistechniquewouldrequirechangesbothintheDSNand the uplink carrier. Therefore, a set of spacecraft in the
onboard the spacecraft. These changes include the addi- common beam of a DSN antenna would all track the
tionofacapabilitytoallowvariableturnaroundratios2to same uplink carrier with the same range code modulated
be able to compensate for relative Doppler shift in order onto it. For all transponders (excepting perhaps one), the
toacquireandremainlockedontheuplinksignal,andthe downlink carrier would be noncoherent with the uplink,
abilitytodifferentiateuplinkcommandsbyspacecraftID. so different transponders would use different downlink
Currently,theDSNprecompensatestheuplinkforDopp- channel assignments. Nonetheless, a two-way coherent
ler; any spacecraft receiving an uplinksignal expects the range measurement could be made for each spacecraft.
frequency of the signal to be nominal, regardless of the There would be, of course, at most one simultaneous
amount of Doppler in the channel. When the uplink is two-way coherent Doppler measurement. TR is most
sharedamongmultiplespacecraftwitheachexperiencing effective at data rates greater than about 2 kb/s. It is
adifferentDoppler,eachspacecraftmustdetectthesignal noted that the TR technology needs further development
in the presence of an unknown frequency shift with beforeitcanbeadopted.
respecttothenominalvalue.
AsdiscussedinPartIofthispublication,recentwork
presents a new approach to ranging, known as telemetry ANTENNA SETUP AND TEARDOWN TIMES
Operationally, the DSN antennas are allotted to users
2Atthepresenttime,theDSNpairstheuplinkanddownlinkchan-
for the duration of a pass (or track). A typical pass lasts
nels using a fixed ratio. For example, for X-band downlinks and
severalhours.Toendapassandbeginanotherone,time
uplinks, each spacecraft’s downlink and uplink frequencies are
relatedbytheratio880/749. is needed for teardown and setup of the antenna.
8 IEEEA&ESYSTEMSMAGAZINE AUGUST2020