Transcript Slide 1

LRO Mission Operations Concept
Rick Saylor
LRO Mission Operations System Engineer
1
LRO Mission Timeline
Launch & Lunar Transfer Phase
Launch &
Ascent
Sep. &
Despin
Deploy & Sun
Acq.
Lunar Cruise
Orbiter Activation & Commissioning
Spacecraft Activation &
Commissioning
LOI
Instruments Activation & Commissioning
~7 to 8 days
Orbiter
Sep.
SA
Deploy
~21 to 48 days
HGA
Deploy
MCC
Activation
Orbit
Instruments Checkout
Complete
S/C Checkout
Complete
Measurement Operations
Routine Opeations
~1 year
Monthly Monthly
SK
SK
Mission
Orbit
Monthly
SK
Monthly
SK
Monthly
SK
Monthly
SK
Monthly
SK
180°
Yaw
Monthly
SK
Monthly
SK
Monthly
SK
Monthly
SK
Monthly
SK
180°
Yaw
Extended Mission Operations
End-of-Mission
Extended Mission Operations Activities
Disposal and Mission
Closeouts
~4 year
Extended
Mission Orbit
NASA’s Goddard Space Flight Center
Detailed End
of Mission
Planning
2
LRO at the Moon
Beta 0º
Yaw Maneuver
•
•
Eclipse Season
Beta 76.4°
Beta 76.4°
•
Earth
•
~1 month
Beta 90º
Full Sun
(~1 month)
Orbit
Moon
Full Sun
(~1 month)
Beta 90º
•
Full Earth View
(~2 days)
Full Earth View
(~2 days)
113 Mins
Beta 76.4°
Beta 76.4°
Sun
Eclipse Season
1 Year
Yaw Maneuver
NASA’s Goddard Space Flight Center
Beta 0º
•
Orbit View
Twice a year, LRO will be in full
Sun for roughly 1 month
(Continuous)
Max Lunar Occultation is 48
minutes per orbit
Twice a year, LRO will perform a
yaw maneuver to keep the Sun on
the correct side of the spacecraft
Twice a month, LRO’s orbit will be
in full view of the Earth for a period
of approximately 2 days
Once a month, LRO will perform a
set of station-keeping maneuvers
(combined Delta-V & Delta-H).
Maneuvers will interrupt science for
1 orbit each month (~2 hrs).
Combined with monthly instrument
calibrations
Twice a year (on average) the Earth
will pass between the Moon and
Sun (Lunar Eclipse), interrupting
science for approximately 3 orbits –
Worse case (~6 hrs)
3
Routine Measurement Timeline
LRO Baseline Instruments Operating Modes
~103 W
~105 W
Instrument Avg.
Orbital Power
~105 W
~96 W
~90 W
~90 W
~88 W
~88 W
~6.35 Mbps
Instrument Avg.
Data Rate
~0.14 Mbps
LAMP Operating
Mode
~0.14 Mbps
Constant Data Rate ~20.2 kbps
CRaTER Operating
Mode
HV Enable
HV Disable
Constant data rate ~100 kbps (During Flares), Non flares ~0.2 kbps
Diviner Operating
Mode
Constant data rate ~10.6 kbps
LEND Operating
Mode
Constant data rate ~0.035 kbps
LOLA Operating
Mode
Constant data rate ~10 kbps
LROC Operating
Mode
Constant Data Rate ~20.2 kbps
WAC
WAC (1 Mbit Image/Sec)
LROC
Power
Cycle
NAC 2 (Each Image ~256 MB)
NAC 1 (Each Image ~256 MB)
Non Sun Lit, Total time
~56.5 minutes
NASA’s Goddard Space Flight Center
Moon’s
Pole
Sun Lit ~56.5 minutes
Moon’s
Pole
Non Sun Lit, Total time
~56.5 minutes
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Measurement Operations
•
Mission Orbit:
–
–
–
•
50 km (+/- 20 km)
Approximately 90° lunar equatorial inclination – drifts about 0.5 °/year
Orbit period: 113 minutes
Orbiter Pointing:
–
–
Nadir pointing to control accuracy of 60 arc-sec (3σ) per axis
Pointing stability (3σ per axis):
•
•
•
•
LROC observations
–
–
–
Each NAC image takes 15 seconds to fill the camera buffer
Camera buffer is transferred to the spacecraft SSR in approximately 206 seconds
LROC observations include occasional slews
•
•
•
•
Slews up to 20 degrees are planned
Spacecraft slews are 20 seconds (allow NAC buffer to fill for image). Slew time does not take into account
maneuver and settling time.
LROC requested 3% of the observations include slews and that the slews are evenly distributed over the year
LAMP High Voltage is disabled during Sun-lit portion of the orbit
–
•
5 arc-sec/axis over 1 ms
10 arc-sec/axis over 100 ms
20 arc-sec/axis over 4 sec
Remaining instrument components remain powered
CRaTER peak data rate is 100 kbps during solar flares, during non flare conditions, ~0.2
bps.
NASA’s Goddard Space Flight Center
5
Ground Network Scenario
S-Band Support Scenario
30
mins
00:00z
30
mins
30
mins
30
mins
06:00z
30
mins
30
mins
30
mins
30
mins
12:00z
30
mins
30
mins
30
mins
18:00z
30
mins
24:00z
Ka-Band Support Scenario
Data Storage
Data Storage
45 mins
45 mins
~68 mins
00:00z
06:00z
NASA’s Goddard Space Flight Center
12:00z
18:00z
24:00z
6
Ground Network Concepts
• S-Band supports scheduled every orbit, each contact is 30
minutes
– Requirement to receive ~12 hrs worth of Doppler/Range tracking
everyday, 30 minutes every orbit.
– S-Band supports will overlap with Ka-Band supports to perform close
loop file transfers
• Two Ka-Band supports approximately 45 minutes in duration
– Over the two contacts, orbiter will dump the previous days worth of
measurement collection
– Margin is needed for each support to retransmits portions of the data
files
NASA’s Goddard Space Flight Center
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Measurement Downlink Concept
1 Ka-Band Site, 2 consecutive Passes Scenario
~68 Minutes
Between Contacts
45 mins
45 mins
Contact #1
Ø
Ø
Ø
Ø
Contact #2
1282 minutes
555 Gbits
1,110 Gsyb
285 Msyb/s
Ø
Ø
Ø
Ø
Ø Data Remaining after contact:
340 Gsyb
Ø Data Remaining after contact:
0 Gsyb
Ø Minutes Remaining for CFDP:
0 minutes
Ø Minutes Remaining for CFDP:
19.4 minutes
Time since last dump:
Data Collected:
Symbols (To Be Dumped):
Symbols D/L Rate:
NASA’s Goddard Space Flight Center
Time since last dump:
Data Collected:
Symbols (To Be Dumped):
Symbols D/L Rate:
113 minutes
49 Gbits
438 Gsyb
285 Msyb/s
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On-Board Measurement Storage
Raw Data
LROC
518 Gbits
SSR
LEND
3 Mbits
LOLA
864 Mbits
Daily Data
(Raw): 533
Gbits
LAMP
942 Mbits
CRaTER
8.64 Gbits **
Diviner
916 Mbits
S/C
2.8 Gbits
Daily Data
(CCSDS OH):
575 Gbits
125 Mbps
Ka
Comm
Card
142.5 Mbps
Ka
Xmit
R-S
Encoding
284
Msymbols
Daily Expected Data Volume
Ø Total Orbiter Data Volume (CCSDS OH):
Ø Total Orbiter Data Volume (w/RS):
Ø Total Orbiter Symbols:
575 Gbits
656 Gbits
1,311 GSymbols
Ka-Band Ground Site
** Data Rate During Solar Flare Condition
NASA’s Goddard Space Flight Center
To MOC (GSFC)
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