Mission Update: June 2017

Home , 112 Iphigenia, 230 Athamantis, 248 Lameia, 720 Bohlinia

Lucy Lim

Assistant Project Scientist NASA/Goddard Space Flight Center

Small Bodies Assessment Group 2017 June Powered On – Nominal ■ Powered Off – Nominal ■ SPACECRAFT SNAPSHOT STATUS Not powered since launch ■ 6-June-2017 Suspect ■ Issue ■

C&DH ■■ Thermal ■ IMU ■■ EPS ■

RWAs ■■■■ Solar Panels ■ LIDARs ■■ SATAGs ■ Star Trackers ■■ Propulsion ■ TAGSAM ■ SRC ■

SPACECRAFT ■

OLA ■ O – SamCam ■ O – PolyCam ■ O – MapCam ■ LGA -X ■ REXIS ■ MGA ■

T – NavCam ■ LGA +X* ■ T – StowCam ■ HGA* ■ *HGA/TWTA-1 in OTES ■ SDST ■■ contact, +X LGA/TWTA- OVIRS ■ TWTA* ■■ 2 carrier only PAYLOADS TELECOM Navigation Status

Current Orbit Diagram

As of June 07, 2017, Launch+271 days:

Earth Range = 0.53 AU (↓) Sun Range = 1.23 AU (↑) Sun-Probe-Earth Angle = 54 deg (↓) One Way Light Time = 04:20 mm:ss (↓) Round Trip Light Time = 08:40 mm:ss (↓)

3 Recent and Upcoming Mission Activities

• First science activity: Earth Trojan Asteroid Search, Feb. 2017 • Participating Scientist Program (Asteroid Operations) Step-2 due 11 July 2017 • Launch + 10-month Calibrations • 2017-07-26 through 2017-08-03: OVIRS, OCAMS calibrations; OTES, OLA, REXIS checkouts • 2017-08-13 through 2017-08-16: REXIS Solar X-ray Monitor (“SXM”) calibration • Earth Gravity Assist (“EGA”), 22 Sept. 2017 • Observations on EGA+1d, +3d, +6d, contingency +10d • Asteroid Arrival at (101955) Bennu, Fall 2018

4 Goals of OSIRIS-REx Earth Trojan Asteroid Search

• Observing geometry for L4 region was superior to that from Earth • Closer to objects • Lower phase angle OSIRIS-REx on Feb 9 • One disadvantage: OCAMS MapCam has small aperture (1.5”) so brighter limiting magnitude than Earth-based systems

• Operational test of OSIRIS-REx • First science observations by mission • Test of spacecraft and OCAMS instrument performance OSIRIS-REx on L4 on Feb 9 • Test of J-Asteroid science planning and commanding Feb 20 tool • Test of astronomical software and data reduction processes • Dry run of 10-cm natural satellite searches to be conducted at Bennu • Dry run of OpNav image planning and reductions L4 on Feb 20 (Jupiter as target) • Lessons learned during the Earth Trojan search are already influencing planning of near-Bennu observations Earth Trojan Asteroid Search: Feb. 9-20, 2017

• Daily mosaic of 3x3 MapCam fields visited 5 times over ~4.2 hours (~51 min between visits) • Each visit consisted of 1 10-s and 2 30-s Pan images • Total of 90 fields and 1350 images as part of ETAS science observations

• Estimate of what we could have detected at a MapCam limiting magnitude of 14.0 in 30s exposures: • On Feb 9: • for phase angle of 0°, range of 0.04 au • H = 20.9 = diameter of 180 to 400m • On Feb 18: • for phase angle of 0°, range of 0.01 au • H = 23.6 = diameter of 50 to 110m • cf. PanSTARRS, Catalina limit of H~19 for L4 objects (Tricarico 2015) Earth Trojan Asteroid Search: What we found

• Zero Earth Trojan asteroids • 17 Main belt asteroids were detected • 12 Victoria V=10.4 Feb 11/12 • 36 Atalante V=13.3 Feb 11/12 • 47 Aglaja V=12.0 Feb 13/14/17 • 55 Pandora V=12.0 Feb 19/20 • 112 Iphigenia V=13.4 Feb 14 • 144 Vibilia V=12.5 Feb 13 • 172 Baucis V=12.3 Feb 11/12 • 230 Athamantis V=10.5 Feb 11/12 • 245 Vera V=13.0 Feb 14/17 • 247 Eukrate V=12.6 Feb 11/12 • 248 Lameia V=13.2 Feb 20 • 250 Bettina V=12.2 Feb 19/20 • 258 Tyche V=12.9 Feb 13/14/17/18 • 327 Columbia V=13.8 Feb 10 • 332 Siri V=13.7 Feb 09 • 720 Bohlinia V=13.6 Feb 09 • 1013 Tombecka V=13.1 Feb 13/14/17/18

• Also detected one planet (Jupiter) and four natural satellites (Europa, Io, Ganymede, Callisto) • Catalina Sky Survey (CSS) asteroid detection software • Ongoing analysis by Saverio Cambioni and Renu Malhotra Earth Gravity Assist: 2017-09-22 Earth Gravity Assist: 2017-09-22

Earth Gravity Assist: Earth Range (km) and Earth/Moon Phase Angles

• Sept. 22, 2017 16:53 UTC • Time of Closest Approach • EGA @ range of 25k km

3500000 180 Earth Range 170 160 Earth Phase Angle Moon Range 150 2625000 140 Moon Phase Angle Lockheed Blackout 130 120 Lockheed Blackout Instrument Observation Window 110 100 1750000 Instrument Observation Window 90

Range (km) 80 70 60 875000 Phase Angle (degrees) 50 40 30 20 10 0 -96. -71.6 -47.2 -22.8 1.6 26. 50.4 74.8 99.2 123.6 148. 0 -96. -71.6 -47.2 -22.8 1.6 26. 50.4 74.8 99.2 123.6 148. Time until Closest Approach (hours) Time until closest approach (hours) EGA: Instrument FOVs Relative to Earth

NavCam SamCam MapCam PolyCam

OTES

OVIRS

EGA + 6 d EGA + 9 h

EGA + 3 d

EGA + 4 h EGA + 1 day

• Flat Field Check (NavCam1) OVIRS FOV in light blue • OpNav Rehearsal of Bennu & 4th Magnitude Star OTES FOV in purple Imaging • Earth stands-in for Bennu and its calculated position with respect to background stars will be used to estimate OpNav uncertainty. • Extended Object Radiometry Check (NavCam1 & NavCam2) • OTES/OVIRS Earth Observations (Spectral Calibration / Alignment between OTES/OVIRS/OCAMS) • Observation Type: Rasterscan Slews (8 N-S, 8 E-W) • Instruments: OVIRS, OTES, MapCam (during N-S slews), PolyCam (during E-W slews), SamCam (during E-W slews) • Earth Diameter: 80 to 70 mrad • OCAMS Absolute Responsivity (Earth and Moon) • Moon Limb Imaging (NavCam1) EGA + 3 days

• OTES/OVIRS Moon Observations (Spectral Calibration / Alignment between OVIRS FOV OTES/OVIRS/OCAMS) • Sep 25, 2017 – 00:20 – 01:20 UT • Target: Moon • Observation Type: Rasterscan Slews (4 N-S, 4 E-W) • Instrument: OVIRS, OTES, MapCam (during N-S slews), PolyCam (during E-W slews), SamCam (during E-W slews) • Moon Diameter: 3 mrad • Moon Limb Imaging (NavCam1 & NavCam2) • OCAMS Absolute Responsivity (Earth and Moon) • OTES/OVIRS Earth Observations (Spectral Calibration / Alignment between OTES/OVIRS/OCAMS) • Sep 25, 2017 – 03:40 – 04:40 UT • Target: Earth • Observation Type: Rasterscan Slews (4 N-S, 4 E-W) • Instrument: OVIRS, OTES EGA + 6 Days

• Similar to EGA + 3 days Sep 28, 2017 – 01:40 – 02:00 UT Target: Earth • Sep 28, 2017 – 00:00 UT Observation Type: Point and Stare Mosaic (5x1 mosaic) • Science Observation Window Start Instrument: PolyCam Pan filter • Sep 28, 2017 – 00:00 – 00:20 UT Focus @ infinity (17371) • Slew to first target 10 light + 6 dark exposures

Repeat MapCam and PolyCam observations three times • OTES/OVIRS Earth Observations (Spectral Calibration / Alignment between OTES/OVIRS/OCAMS) • Sep 28, 2017 – 00:20 – 01:20 UT Moon Limb Imaging • Target: Earth Sep 25, 2017 – 03:40 – 04:40 UT • Observation Type: Rasterscan Slews (4 N-S, 4 E-W) Target: Moon • Instrument: OVIRS, OTES, MapCam (during N-S slews), PolyCam Observation Type: Point and Stare Mosaic (1x3 mosaic) (during E-W slews) Instrument: NavCam1 and NavCam2 • OVIRS/OTES Deep Space and Internal Calibrations before and after 27 + 18 = 45 light exposures slews (5 min before and after) • OVIRS Solar Calibrator after slews (10 minutes) • MapCam 10 light + 16 dark exposures Sep 28, 2017 – 04:40 UT • PolyCam 40 light + 4 dark exposures Slew back to s/c nominal position

• Absolute Responsivity (Earth and Moon) Sep 28, 2017 – 05:00 UT • Sep 28, 2017 – 01:20 – 01:40 UT Science Observation Window end • Target: Earth Earth • Observation Type: Point and Stare Mosaic (5x1 mosaic) • Instrument: MapCam • Pan, b’, v, w, x filters • 50 light + 16 dark exposures JOIN THE MISSION ON THE WEB!

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