Observations of NEO
Encounters:
1998 QE2 and 2012
DA14
Nick Moskovitz
NSF Postdoctoral
Fellow
MIT EAPS
2013 SBAG
Washington, DC
11 July, 2013
Collaborators
Rick Binzel (MIT)
Francesca DeMeo
(MIT)
Tom Endicott (UMass)
Franck Marchis (SETI)
Thomas Augesteijn
David Polishook (MIT)
(NOT)
Eileen Ryan (NM
Carl Hergenrother (UA)
Tech)
Bin Yang (IfA)
Bill Ryan (NM Tech)
Tim Lister (LCOGT)
NEO Encounters
Predictable thanks to
exponential growth of
known objects
→ Catalina, LINEAR,
LONEOS,
Spacewatch, NEAT,
Pan-STARRS
ΔMoon = 0.0025 AU
= 60R♁
Geostationary = 6R♁
Roche Limit = 2-3R♁
(JPL Horizons)
(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
(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
1.6
Normalized Reflectance
Nogoya
CM2 Chondrite
RELAB
1.4
(Pieters & Hiroi 2004)
1.2
Visible:
Palomar Hale
200”
(Mike Hicks/JPL)
Near-IR:
IRTF/SpeX
(285263) 1998 QE2
Ch-type
1.0
0.8
0.5
1.0
1.5
Wavelength (microns)
2.0
2.5
(285263) 1998 QE2
Normalized Reflectance
Thermal Emission
Tmax ~ 400 K
2.0
1.5
1.0
1.0
1.5
Wavelength (microns)
2.0
2.5
(285263) 1998 QE2
Opposition-centered Orbital Longitude:
☍
(285263) 1998 QE2
Opposition-centered Orbital Longitude:
☍
Afternoon
Morning
(285263) 1998 QE2
‣ Evolution
of thermal emission → Prograde
rotation?
1.4
Low T
Pre-opposition
1.3
May 11
NEATM h
1.2
1.1
1.0
0.9
May 30
July 5
June 2
Post-opposition
0.8
0.7
0
High T
20
40
60
Phase Angle (deg)
80
May 30 data
courtesy of Ellen
Howell (Arecibo)
and colleagues
Vervack,
Fernandez, Magri
and Nolan
2012 DA14
‣ Discovered
Feb. 23,
2012 by La Sagra Sky
Survey
‣ 40m
asteroid passed at
~4R♁ on Feb. 15, 2013
(NASA/JPL, P.
Chodas)
DA14: Encounter
Predictions
‣
Change in rotation state
‣
Tidal disruption or mass
loss
‣
Induced seismic shaking
(Richardson et al. 1998)
Max. Distance
Avg. Distance
Min. Distance
20
25
30
35
40 45
Post-Encounter Rotation Period (hr)
(Scheeres et al. 200
DA14: Spectroscopy
Visible spectra: Gemini/GMOS NOT/ALFOSC
‣ Linked to CO/CV carbonaceous chondrites(Bell 1988; Gaffey et al.
1993; Burbine et al. 2002)
or FeO-bearing spinel (CAIs)(Sunshine et al. 2008)
‣
Normalized Reflectance
1.6
Pre Flyby
1.4
Ld
1.2
K
1.0
0.8
Post Flyby
0.6
0.4
0.5
0.6
0.7
0.8
Wavelength (mm)
0.9
DA14: Rotational light
Data from: Wise (Israel), VATT (Mt. Graham), Kitt Peak
curve
(Arizona),
•
Hereford (Arizona), Shefford (UK), Magdalena Ridge (New
Mexico)
•
Tumbling rotation state
10.0
Post Flyby
Magnitude
10.5
11.0
11.5
12.0
0.0
0.5
1.0
1.5
Days relative to JD2456339.5
2.0
2.5
Light curve
fit:
P1 = 6.35 hr
P2 = 8.73 hr
DA14: Periodogram
Analysis
Post Flyby
(2013)
6.3
hr
8.9 hr
Light curve
fit:
P1 = 6.35 hr
P2 = 8.73 hr
Light curve
fit:
P1 = 6.35 hr
P2 = 8.73 hr
DA14: Periodogram
Analysis
Post Flyby
(2013)
6.3
hr
8.9 hr
Pre-Flyby (2013)
Magnitude
18.0
18.5
19.0
Power
0.00
50
40
30
20
10
0
4
0.05
0.10
0.15
Time (days)
0.20
0.25
5.5 ± 1
hr
6
8
10
Period (hours)
7.2
7.4
7.6
7.8
8.0
8.2
8.4
-0.5
40
Power
Magnitude
Discovery (2012)
12
14
16
30
20
10
0
4
-0.4
-0.3
-0.2
Days before JD2456339.5
-0.1
4.8 ± 1
hr
6
8
10
Period (hours)
12
14
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
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)
The Mission Accessible Near-Earth Object
PI: Nicholas Moskovitz
Survey
(MANOS)
(MIT)
David Trilling (NAU)
Cristina Thomas (Goddard)
Will Grundy (Lowell)
Mark Willman (UH)
Eric Christensen (UA)
Henry Roe (Lowell)
Francesca DeMeo (MIT)
David Polishook (MIT)
Richard Binzel (MIT)
Michael Person (MIT)
Michael Busch (NRAO)
Spectra, light curves, &
astrometry for >300 subkm, low Δv NEOs
‣ NOAO: 24 nights per
semester for 3 years
Gemini-S
‣ Assets:Gemini-N
1.00
‣
Lowell
UH2.2m
SOAR 4m
CTIO 1.3m
Magellan
Number
100
0.01
Previously Characterized NEOs
80
60
40
20
0
25
20
Number
Kitt Peak 4m
Diameter (km)
0.10
Predicted Sample for 2014
15
10
MANOS
5
Targets
0
15
20
25
H Magnitude
30