IEEE Geoscience and Remote Sensing Magazine - June 2013 - 64

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Engineering Data Files
ADCS Data
FSW Uploads (As Needed)
Command Files (As Needed)

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MicroSat
Eng

Flight Dynamics
Mission Planning with
Constraint Checking
Command Generation
(Loads, Real-Time, CFDP)

Mission
Operations
Center (SwRI)
Internet

Instrument
Eng
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Hawaii
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Science
Operations
Center (UMich)

Instrument Data
Instrument Uploads (As Needed)
Command Files (As Needed)
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Science Data Files
Engineering Data
Instrument Data
Command Files (As Needed)

Command Scheduling
Science Data Files
Engineering Data Files
CFDP Protocol
Command Files (As Needed)

Chile
Australia

USN Ground
Network
(Ops Center)

fIGure 10. CYGNSS ground system overview.

command sequencing allows the team to coordinate
instrument activities with the time periods when the beacons will be observable by the Observatory.
7.2. ground sysTeM oVerVieW
The CYGNSS ground system, as shown in Figure 10, consists primarily of the MOC; existing USN Prioranet ground
stations in Australia, Hawaii, and Santiago, Chile; and the
SOC facility. Additional interfaces between the MOC and
the microsat engineering team and the DDMI instrument
engineering teams are supported. The MOC coordinates
operational requests from all facilities and develops long
term operations plans.
grounD Data network-uSn
CYGNSS selected USN for the ground data network due
to their experience in autonomously acquiring S/C per
our baselined approach. Co-location of a back-up CYGNSS MOC server at the USN Network Management Center
(NMC) can also be supported.
The Observatories within the CYGNSS constellation
will be visible to three ground stations within the Universal Space Network (USN)-located in Hawaii, Australia,
and Santiago, Chile-for periods which average 470-500
seconds visibility per pass. Each Observatory will pass
over each of the three ground stations 6-7 times each day,
thus providing a large pool of scheduling opportunities
for communications passes.
The MOC personnel will schedule passes as necessary
to support commissioning and operational activities. High
priority passes will be scheduled to support the Observatory S/A deployment for each of the constellation microsats.
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For all subsequent stages, the MOC schedules nominal passes for the USN stations for each Observatory in
the constellation per the USN scheduling process. Each
Observatory can accommodate gaps in contacts with
storage capacity for >10 days of data with no interruption of science.
7.3. Mission oPeraTions cenTer (Moc)
During the mission, the CYGNSS MOC, located at the SwRI
Boulder location, is responsible for the mission planning,
flight dynamics, and command and control tasks for each
of the Observatories in the constellation. A summary of the
primary MOC tasks includes:
◗ coordinating activity requests
◗ scheduling ground network passes
◗ maintaining the CFDP ground processing engine
◗ collecting and distributing engineering and science data
◗ tracking and adjusting the orbit location of each Observatory in the constellation
◗ trending microsat data
◗ creating real-time command procedures or command
loads required to perform maintenance and calibration
activities
◗ maintaining configuration of on-board and ground
parameters for each Observatory.
Science oPerationS center (Soc)
The CYGNSS SOC, located at the University of Michigan,
will be responsible for the following items:
◗ support DDMI testing and validation both pre-launch
and on-orbit
◗ provide science operations planning tools
ieee Geoscience and remote sensing magazine

JUNE 2013

Table of Contents for the Digital Edition of IEEE Geoscience and Remote Sensing Magazine - June 2013