C osmic R Ay T elescope for the E ffects of R adiation Cosmic Ray Telescope for the Effects of Radiation (CRaTER): Science Overview Harlan E. Spence, Principal Investigator Boston University Department of Astronomy and Center for Space Physics

C osmic R Ay T elescope for the E ffects of R adiation PhD, Earth and Space Science, UCLA, 1989 Sr. Mem. of the Tech. Staff, The Aerospace Corp., (“casual status” now) Professor of Astronomy, Boston University, 1994-present Lead instrument scientist of Imaging Proton Spectrometer on NASA/POLAR s/c (led design, development, testing, and calibration) Co-I on CEPPAD and CAMMICE energetic particle instruments on POLAR Co-investigator on energetic particle instrument suite on recently-selected SMART consortium for NASA/MMS Mission My Background NASA POLAR IPS instrument and analog boardPOLAR CEPPAD

C osmic R Ay T elescope for the E ffects of R adiation CRaTER Science Team and Key Personnel NameInstitutionRole Harlan E. SpenceBUPI Larry Kepko“Co-I (E/PO, Cal, IODA lead) Justin KasperMITCo-I (Project Scientist) Bernie BlakeAerospaceCo-I (Detector lead) Joe Mazur“Co-I (GCR/SCR lead) Larry TownsendUT KnoxvilleCo-I (Modeling lead) Michael GolightlyAFRLCollaborator (Biological effects) Terry OnsagerNOAA/SECCollaborator (CR measurements) Rick FosterMITProject Manager Bob Goeke“Systems Engineer Brian Klatt“Q&A Chris SweeneyBUInstrument Test Lead

C osmic R Ay T elescope for the E ffects of R adiation Science/Measurement Overview CRaTER Objectives: “To characterize the global lunar radiation environment and its biological impacts.” “…to address the prime LRO objective and to answer key questions required for enabling the next phase of human exploration in our solar system. ”

C osmic R Ay T elescope for the E ffects of R adiation So What? Powerful Solar Variability. Near solar minimum –Few sunspots –Few flares –Quiet corona Giant sunspot 720 –Sudden appearance –Strong magnetic field –Very large –On west limb by January 20 Image credit: J. Koeman January 15, 2005

C osmic R Ay T elescope for the E ffects of R adiation Who Cares? Astronauts, s/c Operators dt < 30 minutes

C osmic R Ay T elescope for the E ffects of R adiation ISS: 1 REM (Roentgen Equivalent Man, 1 REM ~ 1 CAT Scan) –Scintillations –Hardened shelter Spacesuit on moon 50 REM (Radiation sickness) –Vomiting –Fatigue –Low blood cell counts 300 REM+ suddenly –Fatal for 50% within 60 days Also –Two communication satellites lost –Airplanes diverted from polar regions –Satellite tracking problems, degradation in solar panels Magnitude and Scope of Effects?

C osmic R Ay T elescope for the E ffects of R adiation How Big is Big? Potentially Fatal. Apollo 16 in April 1972 Flare on August 7, 1972 Apollo 17 that December Derived dosage 400 REM Michener’s “Space” is based on this event Big Bear Solar Observatory

C osmic R Ay T elescope for the E ffects of R adiation Why Characterize Radiation Sources? To understand risks to: Astronauts –Radiation Poisoning from sudden events –Heightened long-term risk Cancer Cataracts Spacecraft examples –Single event upsets –Attitude (Sun pulse & star tracker) –Radiation damage

C osmic R Ay T elescope for the E ffects of R adiation Galactic Cosmic Rays: Another Source Crab Nebula (ESO) Advanced Composition Explorer

C osmic R Ay T elescope for the E ffects of R adiation When Is It Safe? Almost never. GCR flux is low-level but continuous and has weak solar cycle dependence Intense SEPs (>10 MeV p+) are episodic and approximately follow the solar cycle SEP event occurrence varies with the solar cycle in anti-phase with weaker galactic cosmic ray fluxes (plot courtesy R. Mewaldt, Cal Tech) SEP events Solar Minimum At solar minimum: Min SEP occurrence Max GCR flux

C osmic R Ay T elescope for the E ffects of R adiation

CRaTER As-Proposed Traceability Matrix

C osmic R Ay T elescope for the E ffects of R adiation Science Measurement Concept

C osmic R Ay T elescope for the E ffects of R adiation GCR/SCR parent spectra will be measured by other spacecraft during LRO mission Biological assessment requires not the incident CR spectrum, but the LET spectra behind tissue-equivalent material LET spectra are a missing link, currently derived largely by models; we require experimental measurements to provide critical ground truth – CRaTER will provide information needed for this essential quantity Rationale for LET Spectra

C osmic R Ay T elescope for the E ffects of R adiation As-proposed design has evolved in response to selection debrief and as a result of detailed knowledge of s/c configuration and instrument accommodation Science trade studies ongoing to refine telescope configuration – basic design is unchanged; internal configuration modified in response to simulation studies Other science/engineering trade studies are underway CRaTER science requirements essentially unchanged – flowdown to be presented by J. Kasper Science Trades

C osmic R Ay T elescope for the E ffects of R adiation Example Science Trade Study Modification from As-proposed Five-element detector stack with 3 volumes of TEP sandwiched between Six-element detector stack with 2 volumes of TEP sandwiched between D6 D5 A2 D4 D3 A1 D2 D1 Moon Space Cylindrical telescope rather than conical