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Science Principal Investigator: Julie Castillo-Rogez Technology Principal Investigator: Les Johnson (MSFC)

Project Manager: Leslie McNutt (MSFC) Sponsored by NASA HEOMD/Advanced Explorations Systems

https://www.nasa.gov/content/nea-scout

Payload NASA Centers

Strategic Knowledge Gaps Addressed

Mission Concept

BioSentinel ARC/JSC

Human health/performance in high-radiation space environments • Fundamental effects on biological systems

of ionizing radiation in space environments

Study radiation-induced DNA damage of live organisms in cis-lunar space; correlate with measurements on ISS and Earth

Lunar Flashlight JPL/MSFC

Lunar resource potential • Quantity and distribution of water and other

volatiles in lunar cold traps

Locate ice deposits in the Moon’s permanently shadowed craters

Near Earth Asteroid (NEA) Scout MSFC/JPL

Human NEA mission target identification • NEA size, rotation state (rate/pole position) How to work on and interact with NEA surface • NEA surface mechanical properties

Flyby/rendezvous and characterize one NEA that is representative of a potential human mission target

AES EM-1 Secondary Payload Overview

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• Concepts selected in August 2013 • MCR/SRR completed in August 2014 • Design Review (SRR) completed in August 2016

- In Phase C, delivery by end of CY17 • Primary selection criteria:

- Relevance to Space Exploration Strategic Knowledge Gaps (SKGs) - Life cycle cost - Synergistic use of previously demonstrated technologies - Optimal use of available civil servant workforce

• Completed a Non-Advocate Review of the Science Plan

Near Earth Asteroid (NEA) Scout GOALS

– Characterize a NEA with an imager to address key Strategic Knowledge Gaps (SKGs) – Demonstrates low cost reconnaissance capability for HEOMD (6U CubeSat)

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LEVERAGES: • Solar sail development expertise (NanoSail-D, Solar Sail Demonstration Project, LightSail-A/B) • CubeSat developments and standards (MarCO, University & Industry experience) • Commonalities with other AES secondary payloads

Key Technical Constraints: • 6U Cubesat and ~86 m2 single quadrant sail • Target must be within ~1.0 AU distance from Earth due to telecom limitations • Slow flyby (10-20 m/s) with target-relative navigation on close approach

For JPL Internal Use Only 4 "The technical data in this document is controlled under the U.S. Export Regulations; release to foreign persons may require an export authorization."

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Near Earth Asteroid ScoutSat (NEAScout)

<15 cm/pix <50 cm/pix

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JPL IntelliCam (Updated OCO-3 Context Camera)

Target Detection and Approach: 50K km, Light source observation

SKGs: Ephemeris determination and composition assessment (color)

Close Proximity Science High-resolution imaging,

10 /px GSD over >30% surface SKGs: Local morphology

Regolith properties

NEA Reconnaissance <100 km distance at encounter

50 cm/px resolution over 80% surface SKGs: volume, global shape, spin

properties, local environment

Reference stars

Target

NEAScout Targets an NHAT • NHATS database contains targets

from 1 m to >1 km

• Targets accessible to NEAScout are < 50m

• Coordination with NEO Program Office

• Expectations is that ~5 new NHATS targets be found each year, with enhanced assets

– None of the NEO discoveries of the past 3 years worked for NEAScout

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Currently NEAScout has access to only one target at any given time (no target for a few launch windows)

Baseline Target: 1991 VG

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• H=28.4±0.7 • Diameter ~ 5-17 meters • Albedo is unknown • Position is known within ~2700 km (1-σ) but optical observation

opportunity in July ‘17 will decrease uncertainty to a few 100s km • Rotation period between a few minutes and less than 1 hr • Unlikely to have a companion • Unlikely to retain a dust cloud

– Solar radiation pressure sweeps dust on timescales of hours or day

Backup Target 2013 BS45

• Discovered by Spacewatch on Jan 20, 2013 • Observed at Goldstone on Feb 10-13, 4.8 LD • Earth-like orbit, NHATs target • Radar astrometry extended Earth encounter

predictability by ~155 years (J. Giorgini, p. comm.)

Credit: P. Chodas

Feb 12, 2013 Goldstone

• Upper bound on size based on 19 m resolution: D<80 m

• conservative bandwidth ~180 Hz • P=100*D/B~3 minutes • likely dark

Plan for 1991 VG Recovery

• 1991 VG will be in sight from ~July 2017 to March 2018, H~23.5 • Arecibo may be able to observe VG but with low SNR between

January 16-28, 2018 – Doppler uncertainties are 70 Hz on January 16, 2018, would be reduced to

~1 Hz after detection

• Optical observations best from Southern hemisphere – 4-m telescopes ok for astrometry and lightcurves – Larger telescope needed for colors

• Vishnu Reddy (UoA), Andy Rivkin (APL), and Paul Abell to coordinate observations

• Proposal will be submitted to NEOO Program • Community is welcome to participate in observation campaign

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Near Earth Asteroid ScoutSat (NEAScout)

NEA Imager (JPL)

Star Tracker (BCT)

18650 Lithium Batteries (Sony/Panasonic)

LGA (JPL)

Reaction Wheels (4) (BCT)

RCS (VACCO)

Solar Sail (stowed) (MSFC)

Rad-Tolerant Avionics

(JPL)

Iris V2.1 Transponder

(JPL)

Solar Panels & MGA (MMA/TBD/AntDevCo)

Boom Assembly (MSFC)

Active Mass Translator (MSFC)

Sun Sensor (BCT) Mission

Concept • Characterize a Near Earth Asteroid with an

optical instrument during a close, slow fly-by

Payload • Upgraded OCO-3 Context Camera

Mechanical & Structures

• “6U” CubeSat form factor • <14 kg total launch mass • Modular flight system concept

Propulsion • ~86 m2 aluminized Kapton solar sail (based on NanoSail-D2)

Avionics • Radiation tolerant LEON3-F7 architecture

Electrical Power System

• Deployable solar arrays with XTJ GaAs cells (~56 W EOL at 1 AU solar distance)

• 6.2 Ahr battery (3S2P 18650 Lithium Cells) • 9 – 12.5 V unregulated, 5 V regulated

Telecom • JPL Iris 2.1 X-band transponder, 4 W RF output power supports Doppler, ranging, and D-DOR

• 2 pairs of INSPIRE-heritage LGAs (Rx/Tx) • Microstrip array MGA (Tx): ~1 kpbs to 34-m

DSN at 0.75 AU

Attitude Control System

• Nano star tracker, coarse sun sensors, and MEMS IMU for attitude determination

• 15 mNm-s (x4) reaction wheels • Active mass translation system • R-236fa (refrigerant gas) RCS system

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Near Earth Asteroid Scout (NEAScout)

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Reference stars

Target

Target Detection and approach with wide field imaging

Ephemeris determination

Target Reconnaissance with medium field imaging

Shape, spin, and local environment

Close Proximity Imaging Local scale morphology, terrain properties, landing site survey

Science under Constrained Resources AC

TIVI

TIES

C

HAL

LEN

GES

AP

PRO

AC

H

Limited downlink (<4kbps) Large target position uncertainty

Limited downlink (<1-4kbps) Short flyby time (<60 min.) Uncertain environment

Limited downlink (<1-4kbps) Short time at closest approach (<2 min.)

Capture position ellipse in one FOV Image co-adding subwindowing Lossless Compression

Thumbnails, triage, lossless compression, subwindowing Autonomous target pointing (center of brightness)

Summary: Contribution to NEA SKGs

• First imaging and characterization of an NEA smaller than 100 m – Will address SKGs that are relevant to all objects in that class range (e.g., surface

state, local environment)

• First demonstration of a low-cost, SKG-driven mission – Combines asteroid detection/tracking and close proximity science capabilities – Paves the way for multi-spacecraft exploration of NEAs – Complementary to Earth-based surveys with ground truth connection to

astronomical observations

• Complementary to other missions to NEA: OSIRIS REx, Hayabusa 2

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Summary: Contribution to Space Technology • End-to-end demonstration of on-board image processing and

science data prioritization and extraction – Can feed to future missions with tight resources, e.g., outer Solar

system missions

• If successful, NEAScout will carry autonomous navigation software for demonstration – Would help reduce operations cost for future CubeSat/SmallSat

missions • Autonomy drove the definition of new computer

– 0.2 U, <5W, 134MIPS x 2 (full duplex), 8GB memory • 0.5 U camera is science-grade, also used for navigation

– Plug and play addition to future missions • Solar sail pathfinder – first end-to-end solar sail development

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LEON 3 ‘Sphinx’

Going to an NEA with a 6U CubeSat is Hard • Two few targets accessible with <3U propulsion system

– True for chemical propulsion, electric propulsion; solar sail has infinite delta-V but is very slow

• Performance of <1U camera is limited – Constrains the size of the target pool

• Data downlink constraints (1kbps) precludes mosaicking of target’s position uncertainty ellipse – NEAScout can capture full 6-s ellipse of 1991 VG from 40K km – OCC=4 targets requires 100s images – Future on-board target extraction is possible, was considered risk for this mission

• Currently NEAScout has access to only one target at any given time (no target for a few launch windows)

• Future CubeSat missions should assume at least 12 U

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