lunarcubes mission and instrument concept - usra · pdf file · 2014-11-06to the...

LunarCubes Mission and Instrument Concept

LWaDi (Lunar Water Distribution) Orbiter and BIRCHES (Broadband InfraRed Compact High-Resolution Exploration Spectrometer)

P.E. Clark, IACS/CUA/NASA GSFC and Flexure Engineering

D. Reuter, R. MacDowall, R. Mauk, E. Mentzell, J. Hudeck, A. Hernandez, J. Didion, D.

Patel, S. Altunc, G. Crum, J. Generie, P. Calhoun, D. Folta, D. Dichmann, NASA/GSFC

Clark etal LWaDi LEAG 2014 1

Why Lunarcubes? Using the Cubesat paradigm to build user requirements driven ‘pathfinders’ for low-cost multi-platform mission concepts that will ultimately provide next generation exploration through the use of temporal and spatially distributed measurements. Providing access to deep space via the Moon as nearby analogue, technology testbed, and gateway to the solar system. Providing a low-cost alternative for high science yield missions at a time of declining funding and increasing costs for conventional missions. Taking advantage of the decade long evolution of the cubesat model from standardized kits to science-driven, multi-institutional, multi-platform collaborations for LEO applications. Examining the use of cubesat hardware/software for missions that are a representative cross-section of lunar, Mars, and other applications at varying degrees of difficulty (flyby, probe, orbiter, lander).

identifying modifications and new technology needed to support a science-driven deep space mode.

Looking for NASA to expand the CubeSat Launch Initiative which provides launch opportunities for cubesats to LEO as secondaries at no cost, to GEO and beyond. designing a deep space prototype bus, and prototype for a lunar orbiter missions. Building on the exploding interest in cubesat as seen in growing popularity of our LunarCubes Workshops over the last 3 years.


Solar System Exploration Relevance Though cubesats not specifically mentioned in the planetary decadal survey, interest in: • studying interactions (dust/volatiles/charged particles/radiation) • within or between systems (exosphere/surface/magnetosphere) • Requiring temporally/spatially measurements need acquired

simultaneously/sequentially, • imply the need for distributed networks • inexpensively provided by nanosats w/ common bus w/ similar or different payloads. • for understanding planetary evolution and origin, • constraining planetary interior and surface processes, • understanding the role of volatiles. Roadmaps within the various target communities (LEAG, MEPAG…) • mention the need for observations • monitoring these interactions or characterizing places associated with volatile activity • that could be met particularly well by networks of

• impactors, • in situ compact surface packages for environmental or geophysical monitoring, • orbiters for monitoring temporal and spatial changes in dynamic systems.

Compact in situ instruments will also play a crucial role in one of the highest priority goals: sample selection, characterization, and return.


• Enabling broadband spectral determination of composition and distribution of volatiles in regoliths (the Moon, asteroids, Mars) as a function of time of day, latitude, regolith age and composition.

• Providing geological context by way of spectral determination of major minerals.

• Enabling understanding of current dynamics of volatile sources, sinks, and processes, with implications for evolutionary origin of volatiles.

Science Goals Understanding the role of volatiles in the solar system


• High-resolution point spectrometer with compact microcryocooler, 1.5 U in volume, <3 kg, <5 W

• HgCdTe detector for broadband measurements from approximately 1 to 4 microns

• Sufficient spectral resolution (5 nm) to characterize and distinguish important volatiles (water, H2S, NH3, CO2, CH4, OH, organics, oxides, carbonates) and mineral bands

• Flexibility in maintaining spot size (10 x 10 km +/- 10% area) regardless of variations up to 5x in altitude or in using variable spot size at given altitude as application requires

BIRCHES Concept


BIRCHES Prototype

HgCdTe detector with LVF

Compact Cryocooler

Off-axis Parabolic (OAP)

aperture

4-sided adjustable iris field stop

Second OAP Mirror collimates beam

• Broadband IR spectrometer with HgCdTe detector sensitive in near and mid IR range Sufficient resolution (5 nm) to resolve characteristic spectral features

• Compact microcrycooler to ≤ 140K to provide long wavelength SNR >100 • compact optics box designed to remain below 240K • OSIRIS Rex OVIRS heritage design


BIRCHES Compact Version


HgCdTe detector with LVF

Compact Cryocooler

Off-axis Parabolic (OAP)

aperture

4-sided adjustable iris field stop

Second OAP Mirror collimates beam

Some Spectrometer Components

Linear Variable Filter Similar to OSIRIS-REx OVIRS design

Off the shelf tactical cryocooler with cold finger to maintain detector at ≤140K


Detector and Electronics 1024 x 1024 H1RG HgCdTe array


Mission Name: Lunar Water Distribution (LWaDi) Science Rationale distribution of lunar water, water components, other volatiles, minerals as a function

of time of day, latitude, regolith properties Instruments 1 Type of Instrument and Measurement

Broadband point Spectrometer with adjustable spot size with compact cryocooler operating in range 1 to 4 microns with minimum 5 nm spectral

target High incidence angle, highly elliptical, inertially locked Lunar orbit Heritage OSIRIS Rex OVIRS Mass, Power, Volume, 2 kg, 1.5U, 6W Data 25 Mbit/orbit, dedicated X-band downlink for hours every day. Special challenges Limited volume for optics. Maintain Optics below 240K, detector below 140K. in-

space propulsion with adequate ISP and DeltaV in small volume. low energy transfer trajectory.

Science Operational Modes

Dedicated measurement taking during illuminated portion of orbit (12% duty cycle), observing different time of day during each lunar cycle for same areas of coverage.

Duration of Use 9 months to desired orbit with low energy transfer trajectory, minimum of six months in orbit

Pointing and orientation

10 km FOV with 5% error regardless of altitude (varying from 100 to 250 km). Nadir pointing requiring .02 degree control, .002 degree knowledge

Contamination issues protection for optical elements (window) Thermal, mechanical Three radiators to maintain optics box <240K. Subsolar point crossing orbit also

coldest, longest eclipse: thermal design based on this worst case scenario Other Comments Available propulsion system assumes ride to GEO, GTO, E escape and long low energy

transfer trajectory. Communication provides minimum bandwidth requiring some onboard processing.

LWaDi lunar 6U orbiter to determine lunar water distribution as function of time of day, latitude, regolith composition, age

BIRCHES

Batteries

BCT XB1

Iris Transceiver

C&DH Backup Honeywell DM

Main Propulsion

Mechanism Controllers, EPS

ACS Thrusters

X-Band Patch Antennas



Optics Radiator

Thermal Modeling for LWaDi

Table 2 Deep Space/LunarCube Resource Allocations

System Description Heritage Mass kg Volume U W (peak)

ACS/Propulsion Star tracker, sun sensor, Momentum Wheels, propulsion (p)

BCT XB1 (RWA, sun sensor, star trackers), GWU ucat or MIT PETA main and ACS thrusters

1.5 1.5 10 p ACS 60 p transit

C&DH/ Processing Science and engineering management, processing

BCT XB1 (C&DH), Honeywell DM, backup

1.5 1.5 5

Structures/ Mechanisms

Frame, deployer, deployables (Gimballed, stowable Solar panel array, antennas)

PSC 6U deployer, MMA Design Ehawk gimballed solar panels

4

70 (provide)

Mechanism Controllers

For solar panels, thrusters 0.5 0.5 10

Comm Antenna, transceiver INSPIRE IRIS Dual X-band patch antennas, transceiver

0.5 0.5 10

Power Electrical system, conversion, regulation, batteries

GOM batteries, EPS 1. 0.5

Instrument and thermal

Detector, optics, associated electronics, cryocooling; Passive Shielding, Passive cooling

Teledyne 1-4u HgCdTe, tactical cryocooler; thermal in house

1.5 1.5 5

Total 10.5 6.


LunarCube Challenges Mobility/Transportation: LunarCube must be delivered beyond LEO as a secondary payload. We assumed LWaDi would be delivered close to its final orbit, and thus require a compact attitude control system (star tracker, IMU, momentum wheels) and, without the Earth’s magnetic field thus the use of magnetic torquer bars as in LEO, modest microthrusters for momentum dumping. The necessity of engaging in lunar capture and/or changing orbit are more likely (EM1, GLXP landers) and will require 1 to 2 km/sec delta-V, meaning that having a high Isp system capable of generating that level of delta-V will typically be essential.

Solution: The next generation of compact micropropulsion systems, including MEMS-based electrospray and MicroCathode, are already under development, and are capable of providing higher precision maneuvering and attitude control once at the final destination.

Thermal/Mechanical, C&DH: Deep space thermal and radiation protection for the thermal (very cold to very hot) with associated mass and volume penalties. Months to years operation instead of days to months for CubeSat.

Solution: New multi-layer insulating materials, extra shielding, radiation resistant electronic parts and design.


LunarCube Challenges Power Generation : many 10’s watts power and energy storage during eclipse. Solution: Next generation solar panels to generate up to 100W, special packaging of batteries.

Communication: communication over far longer distances without supporting infrastructure available for UHF.

Solution: In short run, focused data-taking and minimal navigation and tracking to minimize downlink bandwidth. In long run, use of infrastructure in form of existing landed assets or carrier at target to allow local (UHF?) data transmission and navigation. Also, use of onboard autonomous optical navigation.

Autonomy: Need for far more internal control, adaptable and stable operation, and ‘smartness’ for proliferating small systems.

Solution: Frontier Synthetic Neural System enabled Intelligent Decision Engine capable of learning and adapting in response to user demand and environmental changes.


The Future

Successful incorporation of LunarCube approach could decrease costs for future planetary exploration by one or two orders of magnitude (e.g., tens of millions as opposed to hundreds of million per year, based on, e.g., comparison of MIT ExoPlanetSat at $5 M vs. the Kepler mission at $600 M; 5-10 2nd generation CubeSat class for cost of one SMEX).

Important science ‘core technologies’ are improving capability of miniaturized instruments, particularly reducing volume of geometry-driven components (optics.

Candidates for LunarCube approach could meet or exceed decadal survey objectives, including sample return or considerably improved in situ measurements.

Science and technology development could occur simultaneously, returning to ‘test by flying’ paradigm of NASA’s early years.

A minimal infrastructure, still under development by NASA in collaboration with the private sector, could get many LunarCubes to GEO or Earth escape for low-cost providing access to cis-lunar/lunar space or the lunar surface to jump-start the process.

Conventional high priority Discovery, Frontier or Flagship class planetary mission concepts could be systematically replaced by distributed SmallSat network alternatives.


Some Deep Space Science Cubesat Missions Under Development Target(s) Description Payload Example Moon, Asteroids, Mars

LWaDi (Lunar Water Distribution orbiter. Volatile forms and components systematics)

broadband IR cryocooled. GSFC (Clark et al)

Moon, Asteroids Lunar Flashlight orbiter. (Surface ices in permanently shadowed ‘cold traps’)

NIR instrument. JPL (Staehle et al)

Moon Magnetic Swirl Anomaly impactor Magnetometer. UCSC (Garrick-Bethel et al)

Moon, asteroids Cold Trap Characterization Impactor Series.

Imager, dust detector, NIR and neutron spectrometers.

U Hawaii (Hermalyn et al)

Asteroid Near Earth Asteroid Scout Imager to characterize asteroid dynamics and surface

JPL

Moon Large aperture low frequency radio Surface Network. Solar radio bursts, early universe study

radio astronomy receiver, riometer, deployable antennas

GSFC (MacDowall et al) JPL (Lazio et al)

Moon, potentially Mars

Charged particle interaction with electrical fields around Moon

Ion spectrometer, plasma wave detector

HTIDES EM1 TerDLES (Farrell et al)

Moon Characterization of galactic cosmic ray environment around Moon

Compact 360 degree field of view high energy cosmic ray detector

HTIDES EM1 SPAGHETI (Wrbanek et al)

MiniMoons Observe, Track, Characterize MiniMoons

Imager and compact sensors to characterize MiniMoons

Clark, Folta, GSFC


Overarching Question: Considering the science priorities and resulting range of science investigations, and the range of potential payloads, what does a 'lunarcube' platform look like? 6U, needs robust propulsion system (>1.5 km/sec delta V) mostly to achieve desired orbit from lunar capture, can carry up to 2U payload, >60W power desirable, needs robust thermal protection design, requires 1 year plus Design Challenge 2 Cubesat Concepts to Cubesat Missions: Applied to this concept 1) Overview science, investigation, operational concept and principal drivers (needs)

volatiles study, low periapsis elliptical inertially orbit, thermal design and mobility 2) Trade space (prioritized needs for which optimized capabilities are needed versus resources (volume, cost, bandwidth) available)? More robust and compact ACS, Comm, Power systems available but at cost. 3) What are your perceived performance limitations, risks, and descope options? Bandwidth limited (comm), delta V limited (but focused mission achievable), thermal design challenging and would be improved with ‘smart’ materials and mechanisms. Radiation exposure risk involving use of RHBD hardware/software and more reliable parts sources. Descope involves taking data on way down to final orbit, baseline is 3 months (rather than 6) in that orbit. 4) Link science objective, measurement, instrument requirements, mission requirements, science product (see chart)


lunarcubes mission and instrument concept - usra · pdf file · 2014-11-06to the...

Documents