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Flight%20Dynamics

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... maintain a minimum altitude of 100 km (TBD) during LOI phase. FDS-2.4. MRD-146 ... Consistent with existing S-band measurements and current lunar gravity model. ... – PowerPoint PPT presentation

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Title: Flight%20Dynamics


1
Flight Dynamics
  • Mark Beckman
  • NASA/GSFC Code 595
  • August 16-17, 2005

2
Document Tree
  • Primary
  • Flight Dynamics Specification 431-SPEC-000063
  • Parent
  • LRO Mission Requirements Document 431-RQMT-000004
  • Two-Way
  • LRO Mission Concept of Operations 431-OPS-000042
  • LRO Propulsion Subsystem Statement of Work and
    Specification 431-SOW-000017
  • Detailed Mission Requirements for the LRO Ground
    System 431-RQMT-000048
  • LRO Ground System Interface Control Document
    431-ICD-000049
  • ACS Pointing Document TBD
  • LRO ACS Spec TBD

3
Lunar Reconnaissance Orbiter (LRO)Flight
Dynamics Level 2 Flow DownKey Requirements
Concept/Compliance
Level 3 Requirements
Level 2 Req.
Requirement
Paragraph
Short coast northern TTIs may require coast time
up to 68 min.
LRO shall be launched on a 7925H-9.5 launch
vehicle with a coast time of up to 68 (TBD)
minutes.
FDS-2.1
MRD-24 MRD-3
Daily opportunities further reduced with lighting
constraint.
LRO shall have one daily launch opportunity that
consists of a short coast minimum energy direct
transfer to the moon.
FDS-2.2.1
MRD-24 MRD-3
May add northern insertion if analysis shows dV
improvement or additional daily launch
opportunity required.
LRO shall insert into lunar orbit over the lunar
southern pole and have an initial southern
argument of periselene. (TBR)
FDS-2.4
MRD-11
Lighting constraint at spacecraft separation.
The LRO launch window shall be constrained such
that the nominal spin direction at separation is
within 15 deg of either the Sun or anti-Sun.
FDS-2.2.2
MRD-4
4
Lunar Reconnaissance Orbiter (LRO)Flight
Dynamics Level 2 Flow DownKey Requirements
Concept/Compliance
Level 3 Requirements
Level 2 Req.
Requirement
Paragraph
Safe altitude.
LRO shall maintain a minimum altitude of 100 km
(TBD) during LOI phase.
FDS-2.4
MRD-146
Consistent with frozen orbit for commissioning.
LRO shall maintain a periselene of greater than
200 km (TBD) after LOI1.
FDS-2.4.1
MRD-146
Minimizes finite burn loses.
LRO shall perform up to eight (TBD) LOI maneuvers
to insert the spacecraft into the commissioning
orbit.
FDS-2.4.2
MRD-146 MRD-10 MRD-11
Additional dV saved by performing earlier.
LRO shall perform an MCC1 maneuver prior to L24
(TBD) hours to correct for LV dispersions.
FDS-2.2.2
MRD-3 MRD-25 MRD-10
5
Lunar Reconnaissance Orbiter (LRO)Flight
Dynamics Level 2 Flow DownKey Requirements
Concept/Compliance
Level 3 Requirements
Level 2 Req.
Requirement
Paragraph
No stationkeeping dV required.
The commissioning orbit shall be a frozen orbit
at 30x216 km altitude and a 270 deg argument of
periapsis.
FDS-5.0
MRD-11
Eccentricity, argument of periapsis and longitude
repeat every month within the separation between
consecutive groundtracks.
LRO shall perform a stationkeeping cycle
approximately every 27.4 days.
FDS-4.0
MRD-146 MRD-12
Stationkeeping strategy C complies.
LRO's stationkeeping shall target periselene in
the southern hemisphere 50 of the time.
FDS-4.1.3
MRD-146 MRD-12
Altitude control band dictates frequency of
stationkeeping maneuvers.
The primary mission shall be conducted in a
circular mapping orbit with a nominal altitude of
50 /- 20 km (altitude is measured to mean lunar
surface).
FDS-4.1.2
MRD-12
6
Lunar Reconnaissance Orbiter (LRO)Flight
Dynamics Level 2 Flow DownKey Requirements
Concept/Compliance
Level 3 Requirements
Level 2 Req.
Requirement
Paragraph
May not be possible for all of LOI1
LRO maneuvers shall be performed in view of
S-band tracking stations.
FDS-3.1.6
MRD-147
Consistent with existing S-band measurements and
current lunar gravity model.
LRO shall have a minimum Orbit Determination
Accuracy of 500/18 m (total position RMS/radial
RMS, 1-sigma, post-processed).
FDS-3.1.4
MRD-41
7
Transfer Trajectory
8
Mission Orbit
9
Verification
  • Ground station tracking certification
  • One new antenna (18m at White Sands)
  • Four antennas (Australia, Belgium, Hawaii,
    Sweden)
  • Flight Dynamics Facility (FDF) certifies tracking
    station measurement accuracy
  • End-to-End tests
  • Flight Dynamics Simulations
  • Contingency plans
  • Anomalies

10
Summary
  • Only a few key Level 2 driving requirements
  • All well understood
  • Many derived Level 3 requirements
  • Some in flux as spacecraft design/con ops
    solidify
  • Flight Dynamics Specification details all mission
    design and navigation
  • References to all analysis documents
  • Flight Dynamics is ready to proceed to PDR
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