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Ground-Based Observations of NEO Encounters: 1998 QE2 and 2012 DA14

This study discusses the ground-based observations of two Near-Earth Objects (NEOs), 1998 QE2 and 2012 DA14, including their characteristics, spectral types, rotational properties, and the potential for future research. The study also highlights the importance of rapid response observations and the MANOS mission for studying low-Δv NEOs.

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Ground-Based Observations of NEO Encounters: 1998 QE2 and 2012 DA14

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  1. Ground-Based Observations of NEO Encounters: 1998 QE2 and 2012 DA14 Nick Moskovitz NSF Postdoctoral Fellow MIT EAPS 2013 SBAG Washington, DC 11 July, 2013

  2. Collaborators Tom Endicott (UMass) Franck Marchis (SETI) Thomas Augesteijn (NOT) Carl Hergenrother (UA) Bin Yang(IfA) Rick Binzel(MIT) Francesca DeMeo (MIT) David Polishook (MIT) Eileen Ryan (NM Tech) Bill Ryan (NM Tech) Tim Lister (LCOGT)

  3. ΔMoon = 0.0025 AU • = 60R♁ • Geostationary = 6R♁ • Roche Limit = 2-3R♁ NEO Encounters • Predictable thanks to exponential growth of known objects • → Catalina, LINEAR, LONEOS, Spacewatch, NEAT, Pan-STARRS (JPL Horizons)

  4. (285263) 1998 QE2 • Passed at ~0.04 AU or 15x lunar distance on May 31, 2013 • Diameter = 2.7km Albedo = 6% (Trilling et al. 2010) • Observed by Goldstone and Arecibo → Binary

  5. (285263) 1998 QE2 • Passed at ~0.04 AU or 15x lunar distance on May 31, 2013 • Diameter = 2.7km Albedo = 6% (Trilling et al. 2010) • Observed by Goldstone and Arecibo → Binary • Rare spectral type for NEOs = Ch-type RELAB (Pieters & Hiroi 2004) Visible: Palomar Hale 200” (Mike Hicks/JPL) Near-IR: IRTF/SpeX

  6. (285263) 1998 QE2 Thermal Emission Tmax ~ 400 K

  7. (285263) 1998 QE2 Opposition-centered Orbital Longitude: ☍

  8. Afternoon Morning (285263) 1998 QE2 Opposition-centered Orbital Longitude: ☍

  9. (285263) 1998 QE2 • Evolution of thermal emission → Prograde rotation? Low T Pre-opposition May 11 May 30 May 30 data courtesy of Ellen Howell (Arecibo) and colleagues Vervack, Fernandez, Magri and Nolan July 5 June 2 Post-opposition High T

  10. 2012 DA14 • Discovered Feb. 23, 2012 by La Sagra Sky Survey • 40m asteroid passed at ~4R♁ on Feb. 15, 2013 (NASA/JPL, P. Chodas)

  11. 20 25 30 35 40 45 Post-Encounter Rotation Period (hr) DA14: Encounter Predictions Max. Distance Avg. Distance • Change in rotation state • Tidal disruption or mass loss • Induced seismic shaking Min. Distance (Scheeres et al. 2005) (Richardson et al. 1998)

  12. DA14: Spectroscopy • Visible spectra: Gemini/GMOSNOT/ALFOSC • Linked to CO/CV carbonaceous chondrites • or FeO-bearing spinel (CAIs) (Bell 1988; Gaffey et al. 1993; Burbine et al. 2002) (Sunshine et al. 2008)

  13. DA14: Rotational light curve • Data from: Wise (Israel), VATT (Mt. Graham), Kitt Peak (Arizona), • Hereford (Arizona), Shefford (UK), Magdalena Ridge (New Mexico) • Tumbling rotation state Post Flyby Light curve fit: P1 = 6.35 hr P2 = 8.73 hr

  14. Light curve fit: P1 = 6.35 hr P2 = 8.73 hr DA14: Periodogram Analysis Post Flyby (2013) 8.9 hr 6.3 hr

  15. Light curve fit: P1 = 6.35 hr P2 = 8.73 hr DA14: Periodogram Analysis Post Flyby (2013) 8.9 hr 6.3 hr Discovery (2012) Pre-Flyby (2013) 4.8 ± 1 hr 5.5 ± 1 hr

  16. 1998 QE2 • Binary object passed at ~0.04 AU on May 31, 2013 • Low-albedo → strong thermal emission in near-IR • Phase dependent variability 2012 DA14 • Passed at 4 Earth-radii on February 15, 2013 • No clear evidence for spectroscopic changes • Possible suggestion of change in rotation state

  17. IRTF NEO Rapid Response: Close Encounters of the Asteroid Kind PI: Nicholas Moskovitz (MIT) Richard Binzel (MIT), Bobby Bus (UH), Tim Spahr (CfA), Steve Chesley (JPL) Francesca DeMeo (MIT), David Polishook (MIT) • Multi-semester ToO program at NASA’s IRTF • Observe close encounters, TC3-like impactors, very low Δv objects • Rapid response (<48 hours) capability (Polishook et al. 2012)

  18. The Mission Accessible Near-Earth Object Survey (MANOS) PI: Nicholas Moskovitz (MIT) • Spectra, light curves, & astrometry for >300 sub-km, low Δv NEOs • NOAO: 24 nights per semester for 3 years • Assets:

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