# Presentation: 835757

- and the LCROSS Team

**	**

## LCROSS Mission Selection

- LCROSS mission was selected on 4/10/06, via an ESMD two-step AO
- _Step 1:_ Proposal generation
*(Pre-Phase A formulation phase)*
- _Step 2:_ Down-select of field of (19) proposals to (4)
*(Phase A formulation phase)*
- _Step 3:_ Selection of LCROSS proposal
- (*Phase B entrance)*

## LCROSS Mission Overview

- The LCROSS Mission is a Lunar Kinetic Impactor employed to reveal the presence & nature of water ice on the Moon
- LCROSS Shepherding S/C (S-S/C) directs the 2000[kg] (4410[lb]) Centaur into a permanently-shadowed crater at 2.5[km/s] (1.56 [miles/s])
- ~200 metric tons (220 tons) *minimum *of regolith will be excavated, leaving a crater the size of ~1/3 of a football field, ~15 feet deep.
- The S-S/C decelerates, observing the Centaur ejecta cloud, and then enters the cloud using several instruments looking for water
- The S-S/C itself then becomes a 700[kg] (1,543[lb]) 'impactor' as well
- Lunar-orbital and Earth-based assets will also be able to study both clouds, (which may include LRO, Chandrayaan-1, HST, etc)

**LCROSS Mission Overview**

## LCROSS Project Team

- ARC provides the overall project management, systems engineering, risk management, and SMA for the mission
- Northrop-Grumman provides the S/C and S/C integration for this mission as well as launch systems integration support
- ARC provides the Science, Payloads, and Mission Ops for this mission
- ARC, JPL, and GSFC provides the Navigation and Mission Design role
- JPL is providing DSN services
- KSC/LM is providing Launch Vehicle services
- JHU-APL is providing avionics environmental testing

**LCROSS Project Team**

## LCROSS Science Team

- Tony Colaprete (ARC)
- Geoff Briggs (ARC)
- Kim Ennico (ARC)
- Diane Wooden (ARC)
- Jennifer Heldmann (SETI)
- Tony Ricco (Stanford)
- Luke Sollitt (NGST)
- Andy Christensen (NGST)
- Erik Asphaug (UCSC)
- Don Korycansky (UCSC)
- Peter Schultz (Brown)

- Principal Investigator
- Deputy Principal Investigator
- Payload Scientist
- Observations/Analysis
- Observation Coordinator
- NIR Spectrometers
- Imaging systems
- Science Requirements
- Impact Processes
- Impact Processes
- Impact Processes

## Mission Measurement Objectives

- Confirm the presence or absence of water ice in a permanently shadowed region on the Moon
- Identify the form/state of hydrogen observed by at the lunar poles
- Quantify, if present, the amount of water in the lunar regolith, with respect to hydrogen concentrations
- Characterize the lunar regolith within a permanently shadowed crater on the Moon

**The LCROSS mission rational:**
- The nature of lunar polar hydrogen is one of the most important drivers to the long term Exploration architecture
- Need to understand Quantity, Form, and Distribution of the hydrogen
- The lunar water resource can be estimated from a minimal number of “ground-truths”
- Early and decisive information will aid future ESMD and LPRP missions

**Mission Measurement Objectives**

**Clementine Mosaic - South Pole**

**Neutron Map - South Pole (Elphic et al.)**

## Mission Timeline

**Pre-Launch**

**Launch**

**Transfer**

**VIF ****Ops**

**Pad ****Ops**

**LV ****Ascent**

**Park ****Orbit ****Coast**

**     ****LRO****        Inject/Sep**

**Centaur**** Venting &**
**Re-Target**

**Centaur Handover**
**To LCROSS**

**Checkout**

**TCM-1**

**TCM-2**

**TCM-3**

**     ****Swing by****    Calibration**

**[TCM-4]**

**Day -1**

**Day 0**

**Day 2**

**Day 1**

**Day 3**

**Day 4**

**Day 5**

**Day 6**

**Day 7**

**Cruise**

**Final Targeting**

**Day 15**

**Day 36**

**Day 57**

**Day 69**

**Impact and Data Collection**

**Final**
**Targeting****Burn**

**EDUS****Separation**

**Braking****Burn**

**Data****Collection**

**EDUS****Impact**

**S-S/C****Impact**

**Day 86**

**Day 85**

**Day 64**

**[TCM-6]**

**[TCM-7]**

**TCM-9**

**[TCM-5]**

**TCM-8**

**Day 76**

**TCM-11**

**T****imp****– 8hrs**

**T****imp****– 7hrs**

**T****imp****– 6.5hrs**

**T****imp****– 2hrs**

**T = 0 **

**T****imp****+ 10min**

**TCM-10**

**Mission Timeline**

## LCROSS Mission Animation

- ( Click green button to start QuickTime movie )

**LCROSS Mission Animation**

## Prospecting for Water

- Mass: ~2000 kg
- Velocity: 2.5 km/sec
- Angle: ~75 degrees
**Minimize false positives by controlling EDUS contamination**
- Total H/O bearing materials (e.g. LOX, H2, H2O in batteries) kept below reported and kept below 100 kg
**Minimize false negatives by combining multiple detection methods**

**Crater Diameter, Depth and Excavated Water**
**(Assumes a 10 cm desiccated Layer with uniform water mixing below)**

**...****using 6.5 Billion Joules**

**Prospecting for Water**

## CBEIM Crater Size

**The Current Best Estimate Impact Model (CBEIM)**

- The CBIEM summarizes the results of numerous impact models / assessments.
- Used as the base to drive mission design and instrument selection.
- Efforts continue to refine the model with an update due December, 2006.

## Montecarlo Study of Ejecta Mass

- Montecarlo study of ejecta mass: Simulation varied the crater radius (*R**crat**)*, velocity function exponent ()total mas (*M**e**)*, and ejecta flight angle (See LCROSS technical note “LCROSS ejecta dynamics–Monte Carlo model (09/16/06)“ for details)

**Montecarlo Study of Ejecta Mass**

- Average

- Median

## CBEIM and Sensitivity Studies

**CBEIM and Sensitivity Studies**

## Stages of the Impact Process

**Stages of the Impact Process**

**Ejecta Curtain**

- Simulation using the Ames Vertical Gun Range

- Peter Schultz

## Stages of the Impact Process

- Impact Flash and Vapor Cloud
- Visible Component:
-  Compaction / Intergrain Strain
-  ~0.1 sec
-  F~0.001-1 W m-2 (r=1000 km)
- NIR Component:
-  Blackbody Emission  of Vapor Cloud
-  ~1 sec
-  F~0.01-10 mW m-2 (r=1000 km)
- Total energy sensitive to target properties such as material strength, density and water content.
- Shape of the curve reflects the penetration depth, changes in material competence
- A variety of visible and NIR spectral emissions relate to composition of target material and the fraction of the impactor which vaporizes

**Lunar Flash**

**AVGR Flash**

**Flash Brightness vs Time**

**Stages of the Impact Process**

## Stages of the Impact Process

- After the flash, target material is ejected outward on ballistic trajectories.
- Visible Component:
- Curtain illuminated by sunlight
- Spectral brightness dependant on particle density, size, composition, shape
- Excitation / Florescence from species such as OH- and H2O+
- NIR Component:
- Curtain illuminated by sunlight
- Spectral brightness dependant on particle density, composition, size, shape
- Mid-IR Component
- Curtain thermal emission
- Evolution sensitive to initial ejecta temperature (~100 K), particle size, volatile composition (water) and solar exposure
- Grains with radii <100 m will warm within ~1-100 seconds to ~250 K after solar exposure.
- Spectral brightness dependant on particle density, composition, size, shape

**Stages of the Impact Process**

## Stages of the Impact Process

- After ~5 minutes the bulk of the ejecta “settles” exposing the fresh crater
- Mid-IR Component
- Remnant thermal emission from the crater (=6-15 m)
- At 5 minutes post impact the crater temperature will be ~200 K, against a ~100 K background
- Crater temperature sensitive to water content
- Determination of crater size

**Temperature of Crater Floor After Impact**

**Stages of the Impact Process**

## LCROSS Measurement Plan

- Flash Photometry
- Total brightness in visible and NIR wavelengths
- Visible Spectroscopy
- Visible emission (e.g., OH-, H2O+)
- Surface and ejecta curtain reflectance/absorption
- NIR Spectroscopy
- Surface and ejecta curtain reflectance/absorption
- NIR Imaging
- Surface and ejecta curtain reflectance
- Band-depth maps (=1.4 m)
- Middle IR Imaging
- Surface and ejecta curtain temperatures
- Band-depth maps (=12 m)
- Visible Imaging
- Surface and ejecta curtain reflectance

## Measurement / Technique Trace

***Direct / Strong*** = Very direct measure with little modeling / assumption; highly sensitive
***Indirect / Strong*** = Indirect measure with the goal removed by several steps; highly sensitive
***Indirect / Weak*** = Indirect measure with the goal removed by several steps; moderately sensitive

## LCROSS Orbit & Impact Geometry

**LCROSS Orbit & Impact Geometry**

**Nominal Impact Conditions:**
-  Target impact site: Shackleton Crater (-89.5 lat; 0 lon)
-   Incident impact angle: ~75 deg
-   Impact velocity: 2.5 km/sec

## Basic S/C Concept

**Basic S/C Concept**

- Hybrid propulsive control authority:
- 5[lbf] thrusters for large delta-V
- 1[lbf] thrusters for high precision control authority for attitude control
- No deployments or mechanisms except separation bands
- Straight load path LRO accommodation with high structural margins
- ESPA ring used as the primary spacecraft structure, similar to the AFRL DSX mission.
- TDRSS tank supported on a simple cone on the upper ESPA ring interface
- Propulsion booms and equipment panels attach to Secondary Payload Interfaces

- D1666VS PAF &
- Spacer

- B1194VS PAF &
- Spacer

- Centaur

- ESPA
- Ring

## Space Vehicle Overview

**Star tracker**

**PL Optical Bench **

**Omni antenna (2)**
**- 4 pi steradian coverage**

**Adjustable MGA (2)**
**+/- 20 deg FOV**
**+/- 45 deg adjustability pre-launch**

**Solar array**

**Propellant tank**
**- Mounting skirt**

**PL support structure**

**Thruster mounting brackets (4)**
**- Two 22N and eight 5N total**

**ESPA ring**
**- Six attachment ports**

**LRO derivative spacecraft avionics distributed on 5 equipment panels**
**C&DH, PSE, PDE, STA, IRU, Transponder, RF components**

## Payload Overview

**9 Instruments:**
**1 Visible Context Camera:**
- 4 color, 6 degree FOV, <0.5 km resolution at T-10 min to S-S/C impact
**2 NIR Cameras**
- 1.4 m water ice band depth maps
- 1 km resolution at T-10 min
**2 mid-IR Cameras**
- 7 and 12.3 m
- < 0.5 km resolution
**1 Visible Spectrometer**
- 0.25 to 0.8 m, ~0.002 m resolution
**2 NIR Spectrometers**
- 1.35 to 2.45 m, 0.012 m resolution
**1 Total Visible Luminance Photometer**
- Broadband from 0.6 – 1.2 m, sample rate >1000 Hz, < nW NEP @ 1000 Hz

**Payload Overview**

## Instrument Sensitivity Studies

- LCROSS S-S/C Utilizes backscattered solar light to make water absorption measurements (Differential Absorption Spectroscopy)
- Ejecta Curtain Scattering Assumptions (for NIR):
- Dominant Particle Radius = 45 mm
- Particle Density = 2000 kg/m3
- Single Scatter Albedo = 0.8
- Asymmetry Factor = 0.8
- q = 30°

**Earth-Sun-Moon Geometry**
**30 °>q>160°**

**Instrument Sensitivity Studies**

- q

**Backscatter Geometry from an **
**Solar Illuminated Curtain**

## Instrument Sensitivity Studies

**Time after impact, t = 60 sec**

- N = 1 scan

- N = 10 scans

- a)

- b)

**NIR Spectrometer Sensitivity to 1% Regolith  Water Concentration**

## Instrument Sensitivity Studies

**Instrument Sensitivity Studies**

- Instrument Sensitivity Example – Visible and MIR Cameras

- Camera Resolutions

- Each point represents a IR camera image

- Camera FOVs

- Maximum Expected EDUS Crater Rim Diameter

## Impact Observations Support

**Potential Supporting Platforms**
- LRO
- International lunar missions
- Earth-orbiting
- Ground based
**These platforms can provide unique vantage points and capabilities to monitor the impact event for water.**
**LCROSS provides support to these missions in the form of science rationale, impact expectations, observation recommendations, and technical data for observation (e.g., timing, direction for telescope pointing).**
- Working directly with Facility/Instrument leads to plan observations (e.g., HST, SWAS, LRO, Keck).
- LCROSS Co-I has participated in the observation of SMART-1 to gain experience in observing the moon using large earth based telescope.
- Information will be provided through a web portal, modeled after the very successful Deep Impact mission.

**Impact Observations Support**

**LRO**

**HST**

**Keck**

## Impact Observations Support

- 

**The opportunity for ground based assets to observe the impact depends on the date and time of impact:**
- Phase of the moon:  >30° from new or full moon
- Moon position in the night sky: <2 air masses (>45 ° from horizon) with >2 hours of observing time

- 

**Full**
**Moon**

**New**
**Moon**

- 

## Impact Observations Support

**Platform / Instrument to Measurement Trace**

## LCROSS Payload Data Plan

- Receive Level-1 data (uncalibrated) from MOS
- MOS station to Science station
- All calibration and analysis performed by Science Team
- Analysis / Retrieval routines developed prior to impact
- Will adopt the LRO coordinate system
- Impact + 3 months:
- The LCROSS payload data will be calibrated and reduced to physical units
- A report on the LCROSS payload results will be delivered to LPRP and ESMD
- Impact + 6 months:
- The LCROSS Payload data will be appropriately formatted and delivered to the PDS

## Mission Design and the Impact

- Performance

- Instrument
- Performance

- Radiance
- Predictions

- Chemistry
- Predictions

- Impact Site
- Selection

- Project
- Constraints

**Trades**

**Inputs / Requirements**

- Mission
- Goals

- Impact
- Predictions

- The impact model predictions formed the bases for mission design and instrument selection.

**Mission Design and the Impact**

## Impact Site Selection – The Geodetic Map

**Current uncertainties in lunar geodetic maps are:**
-  ±3-4 km in the horizontal and ~±0.5 km in the vertical.
- Newest USGS map (due in January 2007), these errors may be as small as ~±1 km in the horizontal.
**This error will be reduced by the time of impact:**
- Using LRO data can reduce current uncertainty by a factor of ~2.

**Impact Site Selection – The Geodetic Map**

**Maximum (uncorrelated) targeting error, assuming unimproved geodetic map, is ****±4 - 5 km**** (3********).**
- Current S-S/C targeting performance estimated to be better than ±1 km (3).

**Clementine Mosaic of South Pole**

## Impact Site - Baseline

**The mission baseline is to impact Shackleton Crater**
- Shackleton meets the primary criteria for targeting:
- Shadowed
- Large (D>10 km)
- Apparent association with increased [H]
- High latitude (Impact Angle  >70°)
- Near side with portion of interior visible to Earth

**Impact Site - Baseline**

**Shackleton**

**LP Neutron Counts (****Maurice** **et al.)**
**Blue indicates [H]**

**Radar Topography (Margot  et al.)**

## Impact Site Selection - Adjustments

- Visibility to Earth assets (lat and lon) and Lunar phase (position of terminator)
- Site surface properties, including regolith depth (age) and surface roughness (effects the total ejecta dynamics and volume)
**A Target Selection Committee will consider all candidates and weigh their merit against:**
- Project constraints (e.g. targeting accuracy)
- Project impact (due to departure from baseline)
- Primary and secondary considerations.

**Impact Site Selection - Adjustments**

## Impact Site Selection - Process

- Targeting Committee

- Workshop
- Input

- Project Impact

- ESMD
- / LPRP

- Other Input

- Project
- (Baseline)

- “Top Five”

- Project
- (Final)

## Backup Slides

- Backup Sides

## The CBEIM and Centaur Separation Time

***CBEIM Ejecta Curtain Geometry***

**EDUS Separation Selection**
- To maximize S-S/C instrument response, instrument FOV should be filled at peak sunlit ejecta opacity
- Sunlit ejecta opacity:
- Maximum sunlit ejecta mass (assuming a 2 km sun-mask) occurs at ~1 min after impact
- At 1 min after EDUS impact the ejecta curtain radius, *R*, is *R*~5 km, and at 2 min, *R*~15 km
- To maximize the total integrated signal-to-background ratio over the maximum extent of time, the S-S/C should follow the impact by 8-10 minutes.

**The CBEIM and Centaur Separation Time**