Double Asteroid Redirection Test (DART) - NASA’S First Planetary Defense Mission Deane Sibol, Ground Data System Lead Johns Hopkins Applied Physics Laboratory

Double Asteroid Redirection Test (DART) - NASA’s First Planetary Defense Mission Deane Sibol, Ground Data System Lead Johns Hopkins Applied Physics Laboratory

2 Planetary Defense: Mitigation of Asteroid Hazards, a Global Concern Small asteroids hitting Earth, 1988–2019

Chelyabinsk-sized

Diameter: ~20 m

~500 kilotons TNT 2013, every few decades

Tunguska-sized

Diameter: 60–190 m

~5 megatons TNT 1908, every few centuries

Chicxulub-sized

“dinosaur killer” Diameter: 10–15 km 65 million years ago

4 NASA Planetary Defense Coordination Office (PDCO): established 2016

5 Top Priority for a Mitigation Mission Mitigation Techniques for Potentially Hazardous Asteroids (PHA) Defending Planet Earth (2010) Zero PHAs National Academy of Sciences Deep Impact 9P/Tempel 1 Recommendation: “the first priority for a space mission in the mitigation ~150 PHAs area is an experimental test of a kinetic impactor” DART ~5,000 PHAs DART is the first kinetic impact test at a realistic scale for planetary defense Too small to be considered PHAs Defending Planet Earth (2010)

6 DART – Double Asteroid Redirection Test The first mission to demonstrate asteroid deflection with a kinetic impactor

7 Launch July 22, 2021 IMPACT: September 30, 2022

LICIACube (Light Italian Cubesat for Imaging of Asteroids) ASI contribution

DART Spacecraft 65803 Didymos ~600 kg arrival mass Didymos-B (1996 GT) Didymos-A 18.8 m × 2.4 m × 2.0 m 163 meters 1,180-meter separation 780 meters, S-type 6.65 km/s closing speed 11.92-hour orbital period between centers of A and B 2.26-hour rotation period

Earth-Based Observations • Target the binary asteroid Didymos system 0.07 AU range at impact Predicted ~10-minute change • Impact Didymos-B and change its orbital period in binary orbit period • Measure the period change from Earth

8 Didymos: The Ideal Target

It allows a deflection demonstration on an asteroid of the relevant size by changing its orbital period by ~1% about the larger asteroid.

160 meters 780 meters 11.92-hour orbital period 2.26-hour rotation period In 2022, the result can be observed from Earth-based telescopes.

Light Italian Cubesat for Imaging of Asteroids

6.6 kilometers/second (15,000 miles/hour)

6.8 Million Miles from Earth at impact

9 Double Asteroid Redirection Test Didymos A To Scale 780 m

Eiffel Tower 324 m

DART Spacecraft 18.8 m x 2.4 m x 2.0 m

Didymos B Arc de 163 m (mean) Triomphe 49 m

Statue of Liberty One World Great Pyramid Burj Khalifa 93 m Trade Center of Giza 830 m 546 m School Bus 139 m 14 m

10 DART – Double Asteroid Redirection Test DART-1: DART shall intercept the secondary member of the binary asteroid (65803) Didymos as a kinetic impactor spacecraft during its September to October, 2022 close approach to Earth.

DART-2: The DART impact on the secondary member of the Didymos system shall cause at least a 73-second change in the binary orbital period. DART intercepts Didymos B, designing the impact to maximize the deflection to the orbit of Didymos B about Didymos A

11 DART-3: The DART project shall characterize the binary orbit with sufficient accuracy by obtaining ground-based observations of the Didymos system before and after spacecraft impact to measure the change in the binary orbital period to within 7.3 seconds (1-σ confidence).

Discovery Channel Telescope (credit: Lowell Observatory)

DART’s investigation observes the eclipsing binary Didymos system before and after DART’s impact to measure the deflection caused by DART

12 DART-4A: The DART project shall use the velocity change imparted to the target to obtain a measure of the momentum transfer enhancement parameter referred to as “Beta” (b) using the best available estimate of the mass of Didymos B.

“Beta”

(Stickle et al., 2017) DART’s investigation determines and interprets the momentum transfer resulting from the DART impact

13 DART-4B: The DART project Simulation of DART’s impact shall obtain data, in collaboration with ground- based observations and data from another spacecraft (if available), to constrain the location and surface characteristics of the spacecraft impact site and to allow the estimation of the Itokawa at 0.5 m/pix (JAXA)

dynamical changes in the Dynamical modeling of the Didymos system Didymos system resulting from the DART impact and the coupling between the body rotation and the orbit.

Reconstructed shape model

DART’s investigation characterizes the impact site, dynamical effects, and ejecta to fully evaluate the results of DART’s kinetic impactor mission

14 DART: Key Technologies DART will demonstrate key technologies for future planetary defense missions.

Autonomous SMART DRACO Imager, NEXT-C Ion Propulsion ROSA – Roll Out Solar Nav System modified from LORRI Engine Arrays SMART Nav autonomously DRACO (Didymos DART will be the first flight of NASA’s newly developed directs DART to impact Reconnaissance and Asteroid NASA’s Evolutionary Xenon ROSA arrays will provide a Thruster-Commercial (NEXT- compact form and light mass Didymos-B, leveraging Camera for Opnav) is a C) ion propulsion engine and for launch and be deployed in decades of missile guidance modification of the LORRI algorithm development and be about 3x as powerful as space to reach 19 meters instrument used on the New the ion engine on the Dawn from tip to tip. experience at APL. Horizons mission to Pluto and mission. the Kuiper Belt.

15 1 5 DART Spacecraft NEXT-C cover High Gain (top hat) mass: NLT 676 kg Antenna (RLSA) power: ~5000 W DRACO (with cover on) Hydrazine Thrusters

LICIACube

NEXT-C 2.6 m Ion thruster

2 m

Roll Out Solar Arrays (ROSA) 18 m 16 Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO)

▪ DRACO is the DART payload ▪ Derived from LORRI on New Horizons ▪ IFOV is 4.96 μrad binned (2.48 μrad unbinned) ▪ Full FOV is 0.29 degree ▪ CMOS detector ▪ Panchromatic

▪ DRACO is designed to support several tasks ▪ Optical navigation of the spacecraft (OpNav) ▪ Ensure impact with Didymos B (SmartNav) ▪ Refine system properties (e.g., orbit, rotation rate, pole) ▪ Constrain the location of the impact site ▪ Characterize the surface of Didymos B ▪ Determine the shape of Didymos B

17 Know little about the object we are trying to hit

Radar shape model

Images centered on Didymos, moving Preliminary shape model of the through star fields. Didymos primary from combined radar Taken from VLT in Chile, March/April and light curve data, diameter ~780 m. 2019

18 … and won’t know in time to hit it

timeline not to scale

30 days 10 days 8 hours

Camera Continuous Begin pre- 4 hours out detects ground terminal Didymos antenna phase Begin terminal phase system coverage SMART Nav guidance is enabled. Fully Autonomous!!!

19 Terminal Phase Timeline

timeline not to scale

60 min 30 days 10 days 8 hours 4 hours Range: 24,000 km A: ~6.5 pix Camera Continuous Begin pre- Begin 60 minutes out B: ~1.4 pix detects ground terminal terminal Didymos antenna phase phase SMART Nav begins to system coverage target Didymos B instead of primary

Simulated images

20 Terminal Phase Timeline

timeline not to scale

4 min 30 days 10 days 8 hours 4 hours 60 minutes Range: ~1,600 km A: 99 pix Camera Continuous Begin pre- Begin Locked on B: 21 pix 4 min out detects ground terminal terminal target Didymos antenna phase phase Last image to system coverage contain all of Didymos A

Simulated images

21 Terminal Phase Timeline

timeline not to scale

2 min 30 days 10 days 8 hours 4 hours 60 minutes Range: ~800 km A: 197 pix Camera Continuous Begin pre- Begin Locked on B: 41 pix 2 min out detects ground terminal terminal target Didymos antenna phase phase SMART Nav system coverage maneuvers completed, intercept course achieved

Simulated images

22 Terminal Phase Timeline

timeline not to scale

30 days 10 days 8 hours 4 hours 60 minutes Camera Continuous Begin pre- Begin Locked on 20 s out detects ground terminal terminal target Range: ~120 km Didymos antenna phase phase Required image system coverage resolution satisfied Didymos B will fill ~60% of the camera frame Itokawa at 50 cm/pix

23 Only “sort of know” where the object is

Needle in the 4 hrs: ~96,000 Orbital haystack km Didymos Period ~12 Didymos A: system hours ... and ~2 pix 780m 3 hr you have to Separat thread that ion 2 hr ~700m 1 hr DART → needle 163m

24 DART - Through the Eyes of DRACO Small-body Maneuvering Autonomous Real-Time Navigation SMART Nav)

60 min: ~24,000 km A: ~6.5 pix B: ~1.4 pix A-B surfaces: ~6 pix 4 min: ~1,600 km A: 99 pix B: 21 pix A-B surfaces: 90 pix 2 min: ~800 km A: 197 pix B: 41 pix SmartNavA-B surfaces: 179 simulationpix

SmartNav simulation (Mean ecliptic +z = up)

25 How do we know SMART Nav works? On the ground

Category Parameter Distribution Units Mean Std Range Random Excursion M ean or Excursion Excursion Excursion Excursion Excursion Excursion Excursion Excursion Excursion CEMxc puorssiitoionn eErxrcour rsion Excursion Uniform cm - - -6.25 to +6.25 Mass Row_names M C Flag M C Flag V alue Sigma M in M ax % V alue % V alue % V alue % V alue Ine%rtia princVipaallu aexis misal%ignment V alue Uniform deg - - -1 to +1 Vary the moon Properties Orbit Phase Angle (deg) 1 0 0 2.5 -180 180 Inertia principal moment error Uniform % of nominal - - -9 to +9 Target Shape File 0 1 kw4b NA NA NA 0.083 sphere 0.083 rash 0.083 eros 0.083 kleo 0.083 mithra 0.083 kw4a Primary Shape File 0 1 kw4a NA NA NA 0.083 sphere 0.083 rash 0.083 eros 0.08M3ass kleo 0.083 mithra 0.083 kw4b Target Albedo 1 0 0.267 0.0677 0.05 0.95 Property CM position knowledge error Uniform cm - - -2.5 to +2.5 Primary Albedo 1 0 0.267 0.0677 0.05 0.95Vary the Spacecraft Knowledge Target Radius (m) 1 0 81.5 9 40.75 163 Primary Radius (m) 1 0 390 39 195 780 Gyro bias per axis (post-cal) Gaussian microrad/sec 0 10 - Target Spin Rate (period, hrs) 0 1 locked NA NA NA 0.1 2.5 Gyro scale factor error per axis (post-cal) Gaussian ppm 0 20 - Gyro rotational misalignment per axis (post-cal) Gaussian microrad 0 50/3 - Target Orbit Radius (km) 1 0 1.18 0.04 1 1.5 0.025 1.06 0.025 1.3 Gyro non-orthogonality per axis (post-cal) Gaussian microrad 0 50/3 - 2nd Moon Present Flag 0 1 0 NA NA NA 0.1 1 IMU Accel bias per axis (post-cal) Gaussian microg 0 1 - 2nd Moon Radius (m) 0 0 constrained 0 0 0 0.5 50 Run simulations on high fidelity Accel scale factor error per axis Gaussian ppm 0 150 - 2nd Moon Orbit Radius (km) 10 1 0 0 10 100 0.333 30 0.333 100 Accel rotational misalignment per axis Gaussian microrad 0 90 - 2nd Moon Shape File 0 1 kw4b NA NA NA 0.083 sphere 0.083 rash 0.083 eros 0.083 kleo 0.A0c8c3el non-morithhorgaonalit0y. p0e8r3 axis kw4b Gaussian microrad 0 30 - 2nd Moon Albedo 1 testbeds0 0.267 0.06 7(hardware7 0.05 0.95 & emulations 2nd Moon Spin Period 0 1 locked NA NA NA 0.1 2.5 ST Star tracker misalignment (post-cal) Gaussian microrad 0 16 - 2nd Moon Orbit Period 0 0 calculated NA 2nd Moon Orbit Phasing (deg) 1 0 0 NA of0 spacecraft)360 0.33 90 0.33 180 LPS thruster coefficient scale factor error per thruster Gaussian % 0 7/3 - LPS 2nd Moon Orbit Inclination (deg) 1 0 0 NA 0 15 0.5 15 Thruster misalignment Gaussian deg 0 0.2 -

Steady state thrust direction error Uniform deg - - -0.25 to +0.25 EPS Thrust application point Uniform - - - top-of-optic to 28 in. below optic EPS thruster misalignment Gaussian deg 0 1/10 -

26 How do we know SMART Nav works? On the ground Goal: Hit the center

15 meter (1-σ) miss distance is satisfied. All cases hit within 45 meters of aimpoint

27 Testing SMART Nav In Flight: 23 and 60 days after launch and again 100 days prior to impact Do image processing, Practice on guidance and navigation, and moons of Jupiter send data to Earth real time

28 Prerequisite to Impact: Don’t run out of fuel at the end

Likelihood of maneuvering until impact

Final Correction Initial Maneuvers

Maneuver to Didymos B

Tank holds 50 kg of N2H4 Most of the fuel is used early on in Time until Impact (min) the mission

Early simulations show that we maneuver ~65% of time Terminal Phase (last 4 hours)

29 Prerequisite to Impact: Image that asteroid! It sure won’t be happening after impact…

Point this camera Solar arrays are (telescope) challenging at Didymos

30 3031 January 2019 Light Italian CubeSat for Imaging Asteroids LICIACube

LICIACube Description Capable 6U CubeSat provided by Agenzia Spaziale Italiana (ASI) Goals 1- Impact Obtain multiple (at least three) ejecta plume images of DART impact ejecta plume Based on Argomoon CubeSat that will be flying on EM-1 mission evolution over a span of times and phase (first flight of SLS in 2020) angles, to allow estimation of plume density structure Two cameras (goal of 2 m/ pixel resolution imagery) 2- Impact Obtain multiple (> 3) images of crater DART impact site having sufficient resolution to allow measurements of impact crater size and morphology

3 - Non-impact Obtain multiple (at least three) Current conops includes flyby of hemisphere images of the non-impact Didymos ~ 5 min after DART hemisphere of Didymos B impact and downlinking data after 4 - Color/ Obtain images of the ejecta plume event spectral and of asteroid target to characterize imaging color and spectral variations plume & Didymos

31 DART – Double Asteroid Redirection Test Ground Software Heritage

1990s 2000s 2010s One-Off Systems Common Ground Mission / System Architecture Independent Architecture

32 16 – 19 March 2015 Ground Software Mission Operations Center (MOC*) Configurations The same set of software is used in each configuration

▪ Mini-MOC / Hardware-In-The-Loop Simulator Testbed Local ▪ Supports local test of a spacecraft processor subsystem and avionics via a single computer Archive Client/Server

▪ Provides primary user interface for the testbed (commanding and telemetry) Mini-MOC Avionics ▪ Local archive

GSE ▪ I&T MOC DMZ Clients ▪ Supports spacecraft I&T, allowing users to send commands to and receive telemetry from the Command Clients Spacecraft spacecraft under test and GSE Archive Assembly Server Server Command ▪ Central archive in the OPS DMZ OPS DMZ Network Front end ▪ Other users may view status and telemetry information simultaneously from client workstations I&T MOC connected to controlling I&T MOC workstation and in the OPS DMZ

▪ Flight MOC DMZ Clients Command Clients ▪ Supports mission simulations, launch and operations, including via ground stations Archive

Server Server DSN / ▪ Central archive in the OPS DMZ ESTRACK Spacecraft Command OPS DMZ ▪ Other users may view status and telemetry information simultaneously from client workstations Network connected to controlling Flight MOC workstation and in the OPS DMZ Flight MOC *Mission Operations Center (MOC) =~ Satellite Operations Center

33 Typical Ground System Architecture

34 Typical Ground Software Context

Testbeds / HIL Ground Simulators Support (Front End) Equipment

Mission DSN/ESTRACK Design Scheduling

Navigation

DSN/ESTRACK DART Commanding GSW

G&C DSN/ESTRACK Telemetry and Monitor S/C Engineering Subsystem Mission S/W Operations Development 05/16/2019

35 Mission / System Independent Architecture

▪ DART’s Ground Software consists of 71 Computer Software Components (CSC)s ▪ Most CSCs are java applications that run in separate JVM processes or application server ▪ ~40 CSCs are on-line applications running with an L3Harris InControl-NG Telemetry and Commanding system ▪ Remainder are off-line planning or assessment applications ▪ Code is shared across missions and used with mission specific configuration

High (94%) Re-use = Inexpensive DART ground solution

36 Downlink Flow: Many Sources = Lots of Telemetry Virtual Channels! DART Spacecraft DSN / ESA Ground DRACO Image Frames Station Images 3 Mbps max Firmware (containing downlink rate image packets) House- Telemetry Frames Tlm DRACO keeping C&DH Radio (containing Frames Packets real-time packets Files are automatically Housekeeping and/or CFDP downlinked in priority Packets Protocol Data Units) order, using CCSDS File Delivery Protocol

Recorder Image frames are Files of interleaved with real- Packets Processor Module time frames and are independent of SSR/ CFDP data

CFDP Handshaking Operations Center Files with CCSDS Framing NAV, Image Frames DRACO Ops Center, Mission Reconstructed SMART Nav Analysis Archive Raw Images & Ancillary Data

37 Ground Software: Unique Features for DART

Key: ▪ Receive Telemetry Frames from DSN / = R/T and P/B Telemetry = R/T Gateway FITS image format contains image metadata such as ESTRACK @ 3 Mbps list of gaps, image metadata (from first packet), and correlated data - centroids, spacecraft attitude, etc. image_ Spacecraft Telemetry display ▪ Extract image packets from frames and Frames DRACO Image Image Pixels DRACO image (data) Telemetry image_ Telemetry Packets and metadata & Packets reconstruct reconstruct image in near-real-time @ 1 trp_tlm_ InControl image_ annotation (header) distribution correlate FITS FIle image / second during Terminal Phase R/T Tlm R/T Tlm ▪ Correlate additional flight data with Bridge reconstructed image in near-real-time ▪ Overlay image with applicable correlated data and display to users in 2 different Imager to Radio networks (2 seconds)

MOC to Display ▪ Separately, support timely OpNav OWLT DSN/ESTRACK to MOC w/Overlays (36 seconds) (20 seconds) processing of recorded images to (10 seconds)

Navigation Team 00:00:00 00:01:08

38 AIDA – Asteroid Impact & Deflection Assessment International Cooperation for an International Issue

Impact: 2022 Rendezvous: 2026

39 AIDA – International Collaboration for Planetary Defense Hera Advances the Planetary Defense Test that DART Begins

▪ Hera would launch in 2024, arrive at AIDA – Asteroid Impact and Deflection Assessment Didymos in 2026, and conduct a 6- Hera month survey, including: ▪ Directly measuring the Didymos B mass to determine momentum transfer ▪ Investigating the DART impact crater depth and diameter to understand target physical property effects ▪ These measurements can be made four years after the DART impact without loss of value