Transcript Document

Propulsion
Chuck Zakrwski
NASA/GSFC Code 597
August 16-17, 2005
NASA’s Goddard Space Flight Center
20c - 1
Lunar Reconnaissance Orbiter (LRO)
Propulsion System Document Tree
•Level 2
•431-RQMT-000004
•431-PLAN-000131
•431-OPS-000042
•431-ICD-000008
•431-SPEC-000091
•431-RQMT-000012
LRO Mission Requirements Document
Lunar Reconnaissance Orbiter Spacecraft Performance Assurance Implementation Plan
Lunar Reconnaissance Orbiter Concept and Operations Document
Lunar Reconnaissance Orbiter Electrical Systems Interface Control Document
Lunar Reconnaissance Orbiter General Thermal Subsystem Specification
Lunar Reconnaissance Orbiter Mechanical Environments and Verification Requirements
•Level 3
•431-SOW-00017
•431-LIST-000135
•431-RQMT-000045
•431-RQMT-000092
Lunar Reconnaissance Orbiter Propulsion Subsystem Statement of Work and Specification
Lunar Reconnaissance Orbiter Propulsion Subsystem Deliverable Items List and Schedule
Lunar Reconnaissance Orbiter Radiation Requirements
Lunar Reconnaissance Orbiter Thermal Math Model Requirements
•Level 4
•431-SPEC-000136
•431-ICD-(TBD)
Lunar Reconnaissance Orbiter Propellant Tank Specification
Lunar Reconnaissance Orbiter Propulsion Subsystem Mechanical Interface Control Drawing
NASA’s Goddard Space Flight Center
20c - 2
Lunar Reconnaissance Orbiter (LRO)
Propulsion System Level 2 Flow Down Key
Requirements
Level 2 Req.
Level 3: Requirements
Paragraph
MRD 1.1.46
MRD 3.3.46
4.2.1
Concept/Compliance
Requirement
[The propulsion subsystem shall be capable providing the listed] delta-V
requirements for the given functional requirements:
Function
De-spin/tip-off null
Mid course correction
Lunar Insertion
Orbit Maintenance
Momentum Unloading
Ex tended Mission
(m/sec)
2
75
926
200
-----125
Fuel budget calculated using the
given delta-V requirements.
Kg
----------------16
-----
MRD 1.1.26
4.2.1.1
The propulsion subsystem shall be capable of de-spinning the SC after
separation from the third stage of the launch vehicle from a maximum of 5
RPM about the x-axis.
Conceptual design compliant by
means of placement and canting
of thrusters and tank PMD design
specification.
MRD 1.2.22
MRD 3.3.26
4.2.1.1
The propulsion subsystem will also be capable of nulling maximum tip-off
rates of up to 2 degrees per second (deg./sec) in any axis after
separation from the launch vehicle.
Conceptual design compliant by
means of placement and canting
of thrusters and tank PMD design
specification.
MRD 1.3.66
4.2.2
The propulsion subsystem shall be capable of performing all delta-V
maneuvers with a thrust impulse accuracy of better than 5%.
Candidate thruster capable of 5%
or better impulse accuracy.
NASA’s Goddard Space Flight Center
20c - 3
Lunar Reconnaissance Orbiter (LRO)
Propulsion System Level 2 Flow Down Key
Requirements
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
MRD 3.3.54
4.2.4.1
The Propulsion subsystem shall provide a minimum total continuous
thrust level of at least 140 Newtons (N) for all lunar insertion burns in the
+X SC direction. The propulsion subsystem shall be capable for
providing this thrust for at least ninety (90) minutes.
Conceptual design compliant by
use of two 90+N thrusters for
insertion burn.
MRD 3.3.74
4.2.4.3
The propulsion subsystem shall have the capability of providing a
minimum impulse bit of [less than or equal to] 0.3 N*sec in the +X
direction, 0.06 N*sec in + and – Y [and Z] directions over the entire
mission lifetime.
Conceptual design compliant by
use of 22 N ACS thrusters with
acceptable minimum impulse bits.
MRD 1.2.22
MRD 3.3.26
4.2.7.1
{4.2.10.1}
[The total wet mass of the propulsion subsystem shall not exceed 713.3
kg] The maximum amount of propellant shall not exceed 711.1 kg { and
the pressurant gas shall not exceed 2.2 kg}. This propellant allocation
shall include all propellant required for all delta-V and attitude control
maneuvers as well as subsystem residual propellants and uncertainties in
propellant loading. The maximum propellant shall encompass worst-case
(- 3 sigma) subsystem performance.
Conceptual design compliant
using -3 sigma values for specific
impulse and delta-V
requirements.
TBD
4.2.8
The propulsion subsystem shall be designed to use High-Purity grade
hydrazine per “MIL-PRF-26536E with Amendment 1” as the propellant.
Compliant by specification
NASA’s Goddard Space Flight Center
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Lunar Reconnaissance Orbiter (LRO)
Propulsion System Level 2 Flow Down Key
Requirements
Level 2 Req.
Level 3: Requirements
Paragraph
Concept/Compliance
Requirement
GSFC-STD1000 1.2
4.8.9
The propulsion subsystem shall be an all welded subsystem. Use of
threaded mechanical assemblies shall be limited to the fill and drain vale
(e.g., poppet, AN cap, external cap) and the pyro valve initiators.
Compliant by specification
MRD 1.2.26
431-SPEC000136 (TBD)
The propellant tank shall be designed such that fluid motion inside the
tank does not produce a spacecraft/launch vehicle nutation time constant
outside the launch vehicle specification.
Compliance will be demonstrated
by means of “drop tower” tests of
scaled s/c and tanks
NASA’s Goddard Space Flight Center
20c - 5
Lunar Reconnaissance Orbiter (LRO)
Propulsion System Block Diagram
Pressurant Tank
(Helium)
P
P
High Pressure
R
Panel
Pressure Transducer
R
Fill and Drain Valve
P
Pyrotechnic Valve
(Normally Closed)
Cylindrical
Propellant Tank
(PMD)
Filter
Latch Valve
R
R
Fill/Drain
Valve
Panel
Regulator
Propellant
Management
Device
P
5 lbf Thruster
20 lbf Thruster
NASA’s Goddard Space Flight Center
Low Pressure
Panel
Dual
Thruster
Module
#1
Dual
Thruster
Module
#2
Dual
Thruster
Module
#3
Dual
Thruster
Module
#4
20c - 6
Lunar Reconnaissance Orbiter (LRO)
Propulsion System Preliminary Verification Approach
•Components
–All components, with possible exception propellant tank, are expected to have been
previously qualified
–Nutation time constant constraints may require tank re-qualification
–Acceptance testing required of all components (mechanical, thermal, and electrical)
–Thruster acceptance testing to include ‘hot-fire” tests which encompass worst case
thermal environments
•Propulsion Module
–All welded system with NDE of all welds
–Functional tests at pre- environmental, post environmental and launch site include:
Proof, System Leak, Valve Leak, Electrical Functional, Gas Flow Impedance
–Environmental tests options include:
Acoustics, Sine Sweep, Sine Vibration, Thermal Vacuum/Balance
–System designed to be “wet” with test fluid for environmental tests
–Enable plugs in subsystem to prevent inadvertent operation of all valves and catalyst
bed heaters during I&T
NASA’s Goddard Space Flight Center
20c - 7
Lunar Reconnaissance Orbiter (LRO)
Propulsion Summary
•LRO Propulsion driving requirements are defined
•Propulsion functions and delta-V requirements has been established
•Preliminary architecture has been identified which will satisfy driving requirements
•GSFC acquisition of propellant tank allows interface requirements between
subsystems to be defined at appropriate levels
•Interfaces between the propulsion system and the following subsystems have been
defined at Level 3 and are being developed at Level 4:
•Mechanical
•Thermal
•ACS
•Electrical
•Power
•Propulsion system ready to proceed to contractor selection/award and PDR
NASA’s Goddard Space Flight Center
20c - 8