AIDA-DART Asteroid Impact & Deflection Assessment Double Asteroid Redirection Test
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AIDA-DART
Asteroid Impact & Deflection Assessment
Double Asteroid Redirection Test
DART
AIM
Andy Cheng [JHU/APL]
Cheryl Reed [JHU/APL]
Ian Carnelli [ESA, HQs.]
Patrick Michel [Obs. Cote D’Azur, Nice, France]
Stephan Ulamec [DLR]
Goddard Space Flight Center
NASA Team: Johnson Space Center
Langley Research Center
1
Planetary Defense: Mitigation of Asteroid
Hazards, a Global Concern
Small asteroids that hit the Earth, 1994-2013
Chelyabinsk-sized impacts (500 kilotons TNT) every few decades
Tunguska-sized impacts (5 megatons TNT) every few centuries
2
What can be done, if a dangerous asteroid
is discovered that can hit the Earth?
AIDA/DART
Multiple studies of impact threat deflection have cited three techniques:
Kinetic Impactor, Gravity Tractor, Nuclear Device
All techniques require some level of demonstration and validation before
considered viable for implementation in impact emergency response
Kinetic Impactor technology has been assessed as most mature and
most capable of effecting adequate deflection except in cases of short
term warning before impact - highest ranked as ready for flight
demonstration
International participation in any asteroid mitigation / deflection
campaign is highly desirable if not essential to overall acceptability
The AIDA/DART mission is an international collaboration
to demonstrate asteroid deflection by kinetic impact
3
AIDA supports important goals of the
Planetary Defense community
AIDA/DART
Consistent with finding from SBAG 12, January 2015:
“SBAG strongly supports the creation of a NASA Planetary Defense Coordination Office, a
top recommendation of the 2010 NAC Task Force report. Furthermore, SBAG
recommends that this new office (1) pursue goals specified in congressional direction,
such as NEO population survey completion, (2) work towards development of NEO
mitigation technologies through additional funded programs, including flight validation of
the most promising mitigation system concepts, and (3) utilize cross-agency and
international collaborations as warranted in accomplishing those goals.”
Consistent with recommendations from 2011 and 2013 Planetary Defense
Conferences:
“Missions should be planned to demonstrate and validate the most promising deflection
or disruption options” (2011)
“Missions are being proposed that would use kinetic impactors to move an asteroid, and
the impact and motion away from the original path would be verified by observer
spacecraft. Designing these missions and developing the necessary tools and payloads
for these types of actions would verify model predictions and build confidence in our
abilities to deal with an actual threat.” (2013)
4
• AIDA international cooperation
• DART kinetic impactor (NASA)
• AIM rendezvous (ESA)
AIM
Radar
Telescopes
DART
Didymos Binary
AIDA = AIM + DART
5
AIDA: First Full Scale Test of
Asteroid Deflection
• First mission to demonstrate asteroid
deflection by a kinetic impactor
• Measure outcomes of a known impact on
an asteroid at full scale
• AIDA combines US and European space
experience and expertise to address an
Cheng AF et al. (2015). Acta
international concern, the asteroid impact Astronautica, 115: 262-269
hazard.
• First mission to study a binary asteroid and
its origins
• Impact on to secondary allows Earth-
based observations of changes to binary
orbit
• First mission (AIM) to demonstrate
interplanetary optical communication and
deep-space inter-satellite links with Radar image of Didymos
CubeSats and a lander in deep-space L. Benner, Arecibo, Nov. 2003
6
AIDA is relevant for many disciplines
Planetary Defense Science
Deflection demonstration and
Orbital state
characterization
Rotation state
Orbital state AIM‐DART Size, shape, gravity
Rotation state
Deflection Geology, surface properties
Size, shape, gravity
demonstration and Density, internal structure
Geology, surface properties
characterization Sub‐surface properties
Density, internal structure
Orbital state Composition (including
Sub‐surface properties
Rotation state isotopic)
Composition (mineral, chemical)
Size, shape, gravity
Geology, surface
Human Exploration properties
Orbital state Density, internal
Rotation state structure Resource Utilization
Size, shape, gravity Sub‐surface Geology, surface properties
Geology, surface properties properties Density, internal structure
Density, internal structure Sub‐surface properties
Composition (mineral, chemical) Composition (mineral, chemical)
Radiation environment
Dust environment
PDC 2015
AIDA Investigation Summary
AIDA = DART + AIM
Planetary Defense
Demonstrate kinetic impact mitigation technique, measure asteroid deflection
Develop and validate models for momentum transfer in asteroid impacts
Science and Exploration
Understand asteroid collisions
Infer physical properties of asteroid surface and subsurface, interior structure
Data on impact cratering
Test models of binary formation
Demonstrate technologies: optical communication, cubesats, proximity operations
8
AIDA Joint Working Groups – Welcome
AIM DART
AIM Advisory Team led by P. Michel DART Investigation Team co-led by A.
Cheng, A. Rivkin
Working Group 1 [Modeling and Simulation of Impact Outcomes]
• Angela Stickle, Paul Miller, Steven Schwartz
Working Group 2 [Remote Sensing Observations]
• Andy Rivkin, Peter Pravec
Working Group 3 [Dynamical Properties of Didymos]
• Derek Richardson, Kleomenis Tsiganis
Working Group 4 [Science Proximity Operations]
• Stephan Ulamec, Olivier Barnouin
9
JHU/APL Proprietary
DART: Double Asteroid Redirection Test
Target: Didymos binary in 2022
NASA’s DART, a kinetic impactor mission
with supporting Earth-based observing
campaigns
– Full-scale demonstration of asteroid deflection by
kinetic impact, to learn how to mitigate an asteroid
– Understand impact effects, to infer asteroid
physical properties and study long term dynamics
of impact ejecta
– Ground-based observations to measure the binary
period change from kinetic impact to within 10%
– Return high resolution images of target prior to
impact to determine impact site and geologic
context
10
JHU/APL ProprietaryDidymos: Spectral Type and Composition
Observations by Binzel et al. (2004)
and de León et al. (2010)
• Pretty clearly S type
• Not exotic, new type
• Context for Eros/Itokawa
• Most common NEO type
Dunn et al. (2013): L/LL chondrite de León et al. (2010)
best analog, very common 1.6
meteorite type 1.5
Originally from Flora family? 1.4
Normalized Reflectance
1.3
• LL chondrite parent family? 1.2
• Chelyabinsk link? 1.1
1
• Gaspra link? 0.9
Didymos (de Leon et al.)
433 Eros (Binzel et al.)
25143 Itokawa (Binzel et al)
0.8
0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4
Wavelength (m)
11JHU/APL Proprietary
DART: Double Asteroid Redirection Test
Target: Didymos binary in September, 2022
Launch Date Dec 18, 2020
Launch C3 6.0 km2/s2
Arrival Relative Speed 7.03 km/s
Time of Flight 640 days
Maximum Earth Distance 0.21 AU
Solar Distance 0.95 AU – 1.06 AU
Earth Distance at Impact 0.087 AU
Solar Phase Angle 44°
Impact Angle to Orbit Plane 27.5°
DART payload is a single instrument, a high resolution imager
derived from New Horizons LORRI
Support optical navigation and autonomous targeting
Determine impact site and geologic context
12
JHU/APL ProprietaryDART: 2022 Didymos Intercept
DART trajectory remains near 1 AU from Sun,
Earth distance < 0.2 AU.
DART launch energy 6 km2/s2
Impact velocity 7 km/s
Impact event in Sept. 20, 2022 occurs under
excellent Earth-based optical viewing
conditions, with radar study of aftermath
shortly thereafter
SEP architecture may allow impact during
radar observability window
DART launches in Dec 2020 and intercepts
NEA flyby 10 months before Didymos Didymos on Sept 20, 2022
encounter
13DART Spacecraft
Launch Configuration
Orbit Configuration
HGA
LGA
DRACO imager
Three-axis stabilized, thruster control only
Monoprop propulsion
LGA
Star Tracker Single payload instrument: DRACO imager
14AIDA: DART+ AIM Objectives
AIM mission objectives together with DART:
• Determine the momentum transfer
resulting from DART’s impact by
measuring the dynamical state of Didymos
after the impact and imaging the resulting
crater
• Study the shallow subsurface and deep-
interior structure of the secondary after the
impact to characterize any change
• Study the impact response of the target
asteroid and measure distributions of
impact ejecta providing valuable data to
validate impact modelsMomentum Transfer Efficiency
Full-scale measurement at an asteroid
is defined as momentum transferred divided by
momentum input
– If no ejecta, then = 1
– Ejecta enhances momentum transfer, > 1
M is target mass, ∆ is velocity change
ejecta
Enhanced
Incident momentum momentum
transfer
ejecta
16Impact-Induced Binary Orbit Change
The orbit changes depend on orbit phase of the impact –
DART targets close to maximal period change
1% variation in period
change over 34
minute window.
17Modeling and understanding the
outcome of the DART kinetic impact
Scaling law calculations, 300 kg at 7.0 km/s
on Didymos secondary, accounting for
ballistic trajectories of ejecta
Porous target cases predict of ~1.1 to ~1.3
Basalt Weakly Perlite Sand / consistent with simulations, Jutzi & Michel
Cemented /Sand Fly Ash (2014)
Basalt
Basalt case not expected to apply because
β 3.32 1.1 1.23 1.3 of binary formation scenario
R [m] 4.89 3.06 8.47 5.7 Deflection result of kinetic impact is not
appreciably affected by gravity of binary
β* 3.32 1.1 1.22 1.3 companion
Orbiting AIM measurement of crater radius isPost-Impact Observing Prospects
Observation and Modeling of DART ejecta
Didymos primary and secondary are separated by up to
0.02 arcsec when 0.08 AU from Earth
Marginally resolvable with ALMA (sub-mm), Magellan adaptive optics
Post-impact brightening and ejecta stream as extended
object (“coma”) may be observable from Earth
Non- Low porosity, Very high High
porous, moderate porosity, porosity,
strong strength weak weak
Brightening
[mag] -0.08 -0.02 -0.38 -0.12
Coma,
integrated V 17.3 18.8 15.5 16.8
mag
Itokawa gravel size distribution; Miyamoto et al. 2007
19Didymos Observations during 2015
Establishing preferred pole for system
Apparition in spring. Reached V
~ 20.5
Several observers, using
telescopes with 2-4 m apertures
Bad weather limited useful
data.
Observations by Moskovitz and
Thirouin with DCT show mutual
event. 2015 Observations
– This rules out one of two possible
poles, favor low-obliquity,
retrograde “YORPy” option
– Confirming is major goal of 2017
observations
20Preparations for 2017 Didymos apparition
Focusing on Jan-May 2017. Reaches V~20.3
Four goals for 2017 observing:
1. Confirming the preferred retrograde pole position
2. Gathering data to allow BYORP-driven changes in the mutual orbit to
potentially be determined by later observations
3. Establishing whether or not the secondary is in synchronous rotation with
the primary
4. Constraining the inclination of the satellite orbit
Some of these goals met with a few nights of 4-m time, others
require up to 6-m time
Investigating whether HST proposal is warranted
21Outline of 2022 Impact Observing
Campaign
DART impact during excellent apparition:
Didymos at V ~ 14-15, very well placed for
Chile, observable from other observatories
Planetary Radar participation hugely useful
Didymos primary and secondary are
separated by up to 0.02 arcsec when 0.08
AU from Earth
– Marginally resolvable with ALMA (sub-mm),
Magellan adaptive optics
Post-impact brightening and ejecta stream
as extended object (“coma”) may be
observable from Earth
White paper about observing campaign
possibilities in preparation
P/2013 P5 ~250 m,
Debris cloud analogous to YORP-driven observed at 1.1 AU
MBCs?
distance from Earth
22Didymos, 2022-2023
Points 5 days apart
Period of impact
Motion with timeModeling and Simulation of Impact
Outcomes
Working Group Goals
– (1) Determine the expected outcome of the DART impact and its
sensitivity to initial impact conditions.
– (2) Assess the effect of the DART impact on the moon of Didymos,
focusing on implications for asteroid deflection and properties.
Preliminary Modeling Predicts:
– crater diameter of 5-10 m
– β values range from 1–5 using estimated target properties
– The DART impact will change the secondary’s period by ~ 10 minutes
Current Activities
– Benchmarking of hydrocodes and comparison to experimental data
and analytical models
– Investigating sensitivity of momentum transfer to: target properties,
impact conditions, shape effects (target and spacecraft)
– Investigating ejecta dynamics and evolution in the Didymos system
following DART impact
24Modeling and Simulation of Impact
Outcomes
Working Group Goals
– (1) Determine the expected outcome of the DART impact and its
sensitivity to initial impact conditions.
– (2) Assess the effect of the DART impact on the moon of Didymos,
focusing on implications for asteroid deflection and properties.
Impact simulations and scaling rules predict β~1-5 for
reasonable target strength and porosity conditions
Analytical models and preliminary simulations predict crater
diameters of 5-17 m
Orbit evolution studies predict 8-10 minute period change
– For a two-body problem, it is most efficient to impact in direction parallel
to orbit velocity
– For aggregate bodies (e.g., rubble pile), the disturbance of most orbit
parameters (a and i) nearly identical to 2-body case.
25Potential Future Opportunities for the
Community
Participating Scientist Program
Modeling of Event (pre- and post-DART impact)
Observing Campaign (pre-encounter, near-impact, and post-
impact)
Instruments on AIM
26Conclusion
DART successfully completed NASA’s Pre-Phase A study milestone
in May 2015, Mission Concept Review (MCR)
DART is now officially in Phase A! This study phase continues
through September 2016.
– Primary NASA milestone is System Requirements Review (SRR) and
Mission Design Review (MDR), scheduled for August 2016
DART is in tandem with AIM’s Phase A/B1 study phase, and
supports their programmatic milestones
DART will continue to support joint both AIM interfaces and
reviews, and joint AIDA sessions
– The 2nd International AIDA Community Workshop will be held in June
1-3, 2016 in Nice, France. You are all welcomed to attend!!
Consideration underway for maximizing and optimizing
community involvement in getting full success!
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