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Jim Adams NASA Headquarters

Jim.Adams@nasa.gov

January 9, 2009

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  Science Definition Team Progress

  Mission Definition Trade Study Progress

  Major Conclusions & Mission Recommendations

  Technology Progress

  ILN Foreign Partnership Progress

  Future Plans

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SCIENCE DEFINITION TEAM PROGRESS

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ILN ANCHOR NODE SDT HISTORY

  Chartered in March of 2008

  Members Barbara Cohen/MSFC Joe Veverka/Cornell University Bruce Banerdt/JPL Andrew Dombard/University of Illinois Linda Elkins-Tanton/MIT Robert Grimm/SWRI Yosio Nakamura/UT Austin Clive Neal/Notre Dame University Jeffery Plescia/APL Susanne Smrekar/JPL Benjamin Weiss/MIT Tom Morgan/NASA HQ -- ex officio

  Briefings •  Progress Status to Green, July 2008 •  Overview at Lunar Science Conference, July 2008 •  Progress Status to PSS, •  Progress Status to LEAG, October 2008

  SDT Report •  Draft Rev. 4.7 Released January 4, 2009 •  Final due by end of January 2009

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Objective 1: Determine the internal structure of the Moon

  SCEM 2a. Determine the thickness of the lunar crust (upper and lower) and characterize its lateral variability on regional and global scales.

  SCEM 2b. Characterize the chemical/physical stratification in the mantle, particularly the nature of the putative 500-km discontinuity and the composition of the lower mantle.

  SCEM 2c. Determine the size, composition, and state (solid/liquid) of the core of the Moon.

  SCEM 3a. Determine the extent and composition of the primary feldspathic crust, KREEP layer, and other products of planetary differentiation.

Objective 2: Characterize the temperature structure of the lunar interior

  SCEM 2d. Characterize the thermal state of the interior and elucidate the workings of the planetary heat engine.

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SDT Recommendations; January 2009 DRAFT Report

“In summary the SDT concluded that: 1. An International Lunar Network can deliver essential new science that will enhance

our understanding of the moon. 2. Of the major measurement objectives, the implementation of one – heat flow

measurements to a depth of approximately 3 meters – will benefit from immediate investment to determine the relative merits of at least three possible implementations (mole, drill, penetrator).

3. Although some ILN Anchor Nodes goals can be achieved without a nuclear power source, full realization of the objectives on a minimum-mass lander is enabled by a nuclear power system such as the Advanced Stirling-cycle Radioisotope Generator (ASRG), or its lower-powered derivative (DASRG).

4. The SDT felt that the given task was overspecified by a. Insisting on excellent science, b. Specifying an extremely low cost, c. Specifying very small landers to be launched on vehicles under development and of

uncertain performance. The SDT concludes that at least one of these constraints must be relaxed. It cannot be

(a). Therefore, it must be one or both of the other two.”

  Scientific highest level objectives provided by the NRC Report “Scientific Context for the Exploration of the Moon”

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MISSION DEFINITION AND TRADE STUDY PROGRESS

Initial HQ Challenge:   2 landers on single launch   ~$200M Life Cycle Cost   Agency sweep of technology and ideas

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  Operations: Seismic stations must operate in concert with one another. This requires nodes to be simultaneously and continuously operational.

  Number of nodes: Design first 4 case studies for 2 nodes, final case study to be 4 nodes on single launch. From SDT…“4 nodes is the minimum number to accurately locate a shallow moonquake anywhere on the lunar surface; 2 is the minimum to investigate the lunar core”

  Lifetime: 6 years for 4 nodes/shallow moonquakes; 2 years for 2 nodes/deep moonquakes

  Notional Payload: Included seismometer, heat flow probe, EM sounder and Laser Retro-reflector representative instruments

  Descope Priorities: SDT supplied a “Bingo Chart” to assist in assessing the merit of various concepts

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Anchor Node Trade Results Summary

  Baseline Science Lander Point Design •  Size dictates use of DOD spin-off propulsion technology

  Solar Arrays vs Radioisotope Power System •  Alternative concept studies indicate RPS would be required to meet continuous

operation requirement

  Instrument Accommodation •  Vibration isolation is challenging but can be solved

·  102 Hz from Stirling Engine ·  Lander Structure Thermal Disturbances ·  Lunar Surface Thermal Stability

  Launch Vehicle Accommodations •  Given RPS THEN only EELV can accommodate (at this time)

  IF EELV THEN Fly Four Landers on One Flight •  Operations issues •  Budget issues

  Communication may be an issue for far side nodes

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  Direct trajectory to moon with solid stage providing braking burn.

  Structure includes composite decks and metal landing legs for soft landing.

  Liquid bi-propellant landing using high pressure lightweight thrusters and custom tanks.

  Power provided by Derivative ASRG (DASRG) nuclear power source with small batteries to handle peak power.

  Daily data transmission to DSN ground station   Small warm electronics enclosure with heat

pipes & radiator requires no heater power on surface.

  Landing cameras for horizontal velocity, drives sunlit landing (3-4 day launch window).

  Single string electronics with parts selected and tested for 8 year life & radiation tolerance.

Star 27H Braking

Motor

Omni Antenna

Star 27H Adapter

DASRG on isolators

Comm Antennas with mast

Prop Tank (2)

Power Shunt Panel (3)

ACS Thrusters

(6)

Propulsion Panel

DASRG on isolators

Descent Thruster (3)

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Major Conclusions and Mission Recommendations

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  The International Lunar Network would accomplish high priority science by coordinating landed stations from multiple space agencies

  6 Year Lifetime & 4 Anchor Nodes

  4x1 Launch on EELV Preferred

  Baseline Concept Would Require a Small RPS (40-60We)

  KDP-A and Start of Phase A in 2009

  Need Budget and Schedule Assessments

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Enabling Technology Progress

 Small Radioisotope Power System  Light Weight Propulsion

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  Advantage: Meets 60 We power requirement Provides reduced power system mass to enable lowest mass lander

  Risk: development schedule is undefined and may not support a potential ILN launch in the 2012 to 2014 timeframe

  Risk Mitigated by use of full ASRG at ½ fuel load

A Potential Concept Based on Stirling Technology

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Near-COTS DACS Thrusters

High thrust-to-weight ratio thrusters enable lowest mass lander and less thermal energy requirements.

NASA/US Army Partnership to hot fire test these under ILN conditions has been established

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  The International Lunar Network (ILN) is a cooperative effort designed to coordinate individual lunar landers in a geophysical network on the lunar surface. •  Each ILN station would fly a core set of measurements requiring broad

geographical distribution on the Moon, plus additional passive, active, ISRU, or engineering experiments, as desired by each sponsoring space agency.

•  24 July 2008: ILN Charter Signing Ceremony

  Four Working Groups have been established with international participation Working Group 1: Core Measurements Working Group 2: Communications Working Group 3: Site Selection (not yet seated) Working Group 4: Technology

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  International Lunar Network •  Current: Complete ILN Working Group Terms of Reference (TOR) •  Fall/December: Core Instrument and Communications Working Groups

Continue to meet; initial reports due by end of the year •  Fall/March: Enabling Technologies Working Group gets underway, first

priority is power; meetings held 9/08 in Scotland and 10/08 at KSC •  February: Full Group Telecon to discuss status •  March: Next Meeting, in Japan in conjunction with the ISECG

  Anchor Node Project •  November: Release Instrument RFI, currently evaluating 28 responses •  February: Mission Concept Review •  FY09: Decide to Proceed (or not), Detail Architecture in Level 1’s & Start

Phase A •  FY09: Assemble Cost Estimate to Support PPBE (FY11 budget) •  September: Finish Phase A •  Late 2009: KDP-B

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NAC Questions and PSD Responses

1) Are good heat flow measurements possible at the surface by use of the specific methods envisioned for this mission? Requires further study and may require

technology investment.

2) How effective is a seismic network with only two nodes? Why a two- node design? What was the design process that led to two-nodes? How is the epicenter location determined? Two node designation was a previous HQ SMD AA

challenge to the conceptual design team, it is clearly no longer valid except as a result of “graceful degradation.” The epicenter location question requires further study and modeling.

3) Nodes will need to be long-lived. Agreed, we are using 6 years as the design life.

4) Who makes decisions relative to the international interfaces? NASA HQ

5) How were the mission cost estimates developed? Is SMD confident in these cost estimates? No valid cost estimates have been developed yet, only placeholder

budget wedges. NASA will use the PPBE process to adjust the ILN budget as valid cost estimates become available. NASA Cost Commitment will occur at KDP-C.

6) Are there deployment issues associated with the seismometers? Would the ILN seismometer effectiveness (noise) be impacted by putting it under a creaking lander? Yes, there are deployment issues, the concerns have been

addressed in the conceptual design to the first order and will retain a high level of attention until the concerns have been adequately addressed.

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Back-up

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  Instrument attached to ground, well coupled to surface •  Control thermal input to surrounding ground surface •  Provide thermal blanket skirt (diameter 1 - 1.3 m)

  Vibrationally isolate seismometer payload from lander •  Damp lander contributions in 0.5 to 2 Hz critical freq range, •  Minimize transmission of lander disturbance in .01 to 40 Hz range •  Provide freq modes of lander to instrument team

  Thermal stability to +/-5 deg C   Inter-station timing accuracy of better than 5 msec   Multiple nodes simultaneously operating for 1 tidal cycle (6

years) baseline, 2 yr floor   Continuous operation (i.e. day and night)

Stowed (Blanket not shown)

Lander Bottom Deck

Seismometer Deployment Shroud

Deployed

Seismometer Blanket

Seismometer Harness

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Heat Flow Experiment (Mole deployment mechanism used for feasibility assessment)   Lifetime: 2 years   Mole volume allocation: 350x 350x120 mm

•  In the ExoMars instrument, the electronics box fits in this volume   Deployment

•  Hold mole upright, during penetration •  Probe deployed by mole to depth of 3 m •  ExoMars mole accommodated in constant thermal environment

·  Mounted on North side of lander, option for boom mounting

EM Sounding Experiment   Temperature sensors & heaters

•  Maintain > -50 C; accuracy not important but temp knowledge is •  Langmuir probe can withstand 300 deg C

  Deployment •  Three booms @ 1.6 m + vertical mast for Langmuir Probe

  Lifetime •  Baseline: Continuous operation (i.e. day and night) •  Floor: Operation during two geomagnetic-tail passages (six days each)

Magnetometer (2)

Langmuir Probe

Electrometer (3)

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•  Laser Ranging Experiment (passive retroreflector used for feasibility assessment)

–  Design accommodates LRO style reflector –  Pointed to earth within +/- 15 deg, set prior to launch

Mass ~ 600 grams Power - zero (passive) No thermal constraints

11.5 cm

15 cm

Retro-Reflector for Laser Ranging

Deployed Seismometer with blankets

EM Sounding experiment with 3 deployed booms + 1 mast

Deployed Mole for Heat Flow (behind on shaded side)