Apophis Mitigation

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Apophis Mitigation Research Project
Project Kickoff Meeting February 9, 2009
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• Research Project Announcement
• This project will continue the efforts of the
  Aero 426, Space System Design (Fall, 2008), class
  to develop a space mission that will rendezvous
  with the dangerous Near Earth Asteroid (NEA)
  99942 Apophis and apply various technologies to
  deflect its orbit from possible Earth impact
  before its next close encounter on Friday, 13
  April, 2029. Because of the long lead time
  required for orbit deflection, a mature design
  concept for the Deflect Apophis System (DAS) must
  be developed within the next two years. This is
  an ongoing collaboration with NASA Ames and is
  being conducted with international support.
• Starting with the notional design developed in
  Aero 426, research participants will
• (1) Travel to NASA Ames, near San Francisco, to
  work in their concurrent engineering design
  facility for 3 to 5 days, developing a firm
  baseline design,
• (2) Respond to the National Research Councils
  (NRCs) Announcement of opportunity dated
  December 17 and submit a full proposal to the NRC
  by March 20, 2009. For further details, see
• http//www7.nationalacademies.org/ssb/NEO_surveys
  _mitigation.htmlP16_19
• (3) Conduct prototype development of an asteroid
  deflection technology and test it experimentally.
• The above steps will be conducted during the
  spring, 2009 semester and will lead to
  preparation of a proposal (jointly with NASA
  Ames) to NASA HQ for a Discovery-class mission
  during the summer of 09. These activities will
  contribute significantly to our understanding of
  how to mitigate the potential hazards of NEAs.
• We solicit the participation of junior and senior
  undergraduate students and graduate students.
  Students from all departments of engineering and
  science are encouraged to participate. Finally,
  qualified and effective participants will be
  offered summer employment.
• For further information and to volunteer your
  participation, contact
• Dr. David C. Hyland
• Professor of Aerospace Engineering, Wisenbaker
  Chair of Engineering,
• Dwight Look College of Engineering

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Apophis Mitigation Project Kickoff - Agenda

• Introduction to Apophis
• Project History
• Outline of Design concepts to-date
• Three activities
• Proposal to NRC
• Albedo change technology
• Baseline design definition (at NASA Ames)
• Schedule of activities

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Apophis 99942 Background Information
Project Background

• Discovered on June 19th, 2004 by R. A. Tucker, D.
  J. Tholen and F. Bernardi at Kitt Peak
• Orbital models have identified several close
  Earth approaches, occurring roughly every 7
  years. When Apophis passes by in 2029 it could
  pass through a gravitational keyhole which would
  swing Apophis into a collision path with Earth in
  2036
• As an Aten class NEA, Apophis rated as high as 4
  on the Torino scale but has been downgraded to a
  0 as its probability of impact in 2029 has been
  commonly accepted at 1/45,000

Source http//neo.jpl.nasa.gov/apophis
AAA System Design Review
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December 9, 2008
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Apophis 99942 Physical Data
Project Background

• LL-chondrite composition
• Estimated rotational period of 30.57 h
• Keyhole Event April 13, 2029
• Results in resonant return and possible impact in
  April 2036

Sources http//ssd.jpl.nasa.gov/sbdb.cgi?sstr999
42orb1cov0log0discovery
Chesley, Milani, Vokrouhlicky, Icarus 148,
118138 (2000)
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AAA System Design Review
December 9, 2008
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APEP
Project Background

• Agencies from around the world, including
  NASA/JPL, Caltech, and Arecibo, have analyzed and
  identified Apophis orbital elements and physical
  properties with limited levels of accuracy
• Uncertainty in the effects from albedo and
  gravitational forces over time are again causing
  concern about a potential impact with Earth
• The Fall 07 426, Spring 08 401 and Fall 08 402
  classes started the design of the Apophis
  Preliminary Exploration Platform (APEP) mission.
  Objectives were
• Rendezvous with Apophis in 2013, act as a beacon
  to enable precise tracking,
• Measure physical characteristics most relevant to
  improved accuracy of orbit prediction.
• If Apophis is on a collision course with Earth
  and planning of a mitigation mission is started
  after APEP discovers this fact, changing the
  course of the asteroid may be impossible.

AAA System Design Review
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December 9, 2008
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AAA - System Concept Briefing
December 3, 2008
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AAA - System Concept Briefing
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December 3, 2008
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Apophis Preliminary Exploration Platform (APEP)
Mission Statement

• The APEP mission is to rendezvous with the near
  earth asteroid Apophis 99942 to conduct a study
  of physical characteristics and accurately track
  the orbit in order to determine the probability
  of an Earth impact in 2036.

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AAA - System Concept Briefing
December 3, 2008
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Top-Level Mission Profile
Maintain 3 km standoff distance from Apophis for
1 year
Launch APEP mission by 2012
Rendezvous with Apophis after 1 year travel time
Broken-Plane Maneuver to minimize overall ?V
Relay data to ground stations on Earth to
determine Apophis tracking and science
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AAA - System Concept Briefing
December 3, 2008
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Events in the APEP Project History

• Aero 426 (Fall, 2007) students formulated
  notional mission design with final presentation
  in December 2007.
• Project continued in spring semester as the focus
  of the two-semester capstone design sequence Aero
  401-402, Spacecraft Design.
• January 28 30, 2008 Aggies Against Apophis
  (AAA) team travels to the Jet Propulsion Lab to
  conduct concurrent engineering design sessions
  with Team X.
• Result Baseline design serving as the starting
  point for Aero 401
• February 2008 Educational partnership with King
  Abdullaziz City for Science and Technology
  (KACST) initiated.
• KACST personnel join the AAA team, undertake to
  provide design development of APEP Science
  Instruments
• Spring 2008 semester AAA team (Aero 401)
  refines baseline to develop conceptual design.
• Fall 2008 semester AAA team (Aero 402) travels
  to AMES research center to present current
  design.
• The result is a partnership with AMES for a
  proposal effort to NASA HQ
• Formal AM / NASA Ames / KACST partnership under
  negotiation.

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AAA - System Concept Briefing
December 3, 2008
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(No Transcript)
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(No Transcript)
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Rationale for Exploration and Mitigation Mission
Launch Dates
Project Background
2015
2010
2020
2025
2040
2035
2030
We are too late for the 2012 launch. We must
amalgamate the exploration and mitigation
missions for the later launch window.
AAA System Design Review
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December 9, 2008
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Apophis Deflection System
Project Background

• The challenge facing the fall 08, 426 class was
  to develop a system that can sufficiently modify
  the trajectory of Apophis such that it will not
  impact the Earth in 2036.
• A subsidiary goal is to design the spacecraft
  such that it can be fabricated and tested in the
  AggieSat Laboratory.
• The class was originally split into four teams.
  Each team examined multiple methods of
  deflection, including but not limited to
• Gravity Tractor
• Solar Sublimation
• Kinetic Impactor
• Electric Propulsion Devices
• Albedo Modification Systems
• Nuclear Burst
• Each team then investigated one method in depth
  and presented the method to the rest of the
  class. The best design was chosen as the system
  that would be developed by the whole class as a
  unified team.
• The Gravity Tractor was chosen as the best design
  and therefore is the focus of this presentation.
• Albedo modification is being investigated as a
  secondary mitigation technique.

AAA System Design Review
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December 9, 2008
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Deflect Apophis System(DAS) Mission Statement

• The DAS mission is to intercept the near-Earth
  asteroid Apophis 99942 and perturb its orbit to
  prevent an Earth impact in 2036.

AAA Conceptual Design Review
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April 21, 2008
April 21, 2008
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Mission Overview
Top-Level Mission Profile
Maintain 400 m standoff distance from Apophis
for 4 years Deflect via Gravity Tractor effect
Deploy albedo altering experiment during
mitigation
Launch DAS mission by 2022
Rendezvous with Apophis after 5 month travel
time
Relay data to ground stations on Earth to
determine mitigation effectiveness
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AAA System Design Review
December 9, 2008
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Gravity Tractor Concept
Mitigation, Payload, Telecom, and Instruments

• Use Newtons Law of Universal Gravitation
• Use a spacecraft to impart a gravitational force
  upon Apophis to gently move Apophis to a
  non-Earth impacting orbit
• Utilize the 2029 flyby to enhance mitigation
  efforts
• Small changes pre-flyby result in large changes
  in Apophis trajectory post-flyby

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AAA System Design Review
December 9, 2008
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Albedo Change
Mitigation, Payload, Telecom, and Instruments

• Any change in albedo alters solar pressure and
  the Yarkovsky effect
• Fmax 0.70 N from solar pressure and Yarkovsky
  effect
• Orbit Deviation (assuming 25 kg coating)
• By 2036, a 4 change in albedo (beginning in
  2018) will deflect Apophis between 17 and 45
  Earth radii
• Model based on comparison with results of Chesley
  paper

AAA System Design Review
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December 9, 2008
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• Documentation on the design work to-date has been
  placed on the web. Go to
• aeweb.tamu.edu\aero489
• Open folder Apophis Mitigation Project

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Planned Activities

• Three main activities
• Respond to the NRC AO with a mitigation proposal
  (due March 20)
• Conduct technology maturation experiments
• Albedo change deflection technology Design and
  fab the albedo change dispense mechanism Test in
  the STC vacuum chamber
• Working at NASA Ames project design center,
  complete definition of baseline design.(Teamed
  with NASA Ames, submit proposal to NASA HQ for a
  Discovery-Class mission (Summer, 2009))

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Activity 1 Submit proposal to the NRC
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Letter of Intent Submitted to the NRC
Authoring Organization Name Texas AM
University, Dwight Look College of Engineering,
College of Science Description of Proposed
Solution This is a mission concept for
mitigating NEOs. We deflect the orbit of a NEO
away from Earth collision by a near-term
application of the gravity tractor approach,
followed by an albedo modification technique. The
former method is well-known and can be applied
immediately upon the spacecrafts arrival at the
NEO since detailed knowledge of the physical
properties of the NEO is not required. During
gravity tractoring, on-board instruments
determine the spin state, and thermal
characteristics of the NEO in sufficient detail
to model the Yarkovsky effect. With this data, we
apply a novel albedo change device that
dispenses, in a controlled fashion, ionized
powder to selected regions of the NEO surface
which is itself ionized by ultraviolet radiation.
Electrostatic attraction provides the dominant
force that will distribute and bind the powder to
the surface. The author and his AM students have
defined a reference mission to the asteroid 99942
Apophis. We show that a 4 albedo change
(beginning in 2018), using 25 kg of surfacing
material, will deflect Apophis between 17 and 45
Earth radii by 2036, depending on the spin state.
Note that whereas gravity tractoring is of
limited duration, the albedo change treatment can
operate forever.
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Activity 2 Design, Fab Lab Test of Albedo
Change Mechanism

• After review of previous work, we brainstorm a
  variety of albedo change techniques
• Choose one idea
• Is it mechanically simple?
• Is it dynamically simple?
• Is it operationally simple?
• Is it low mass, low cost and effective?
• For the chosen concept
• Analyze performance
• Identify areas of technical uncertainty
• Define experiment (s) to retire uncertainty
• Fab and test
• Document test results for our proposal to NASA HQ

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Albedo Treatment Options
Mitigation, Payload, Telecom, and Instruments

• Paint
• Heavy
• Difficult to apply
• Freezing possible
• Chalk
• Lightweight
• May coat unevenly

• Reflective Sheet
• Very large
• Difficult to open and deploy onto surface
• Glass Beads
• Heavy
• May be covered by dusty surface
• Easy to carry and release

AAA System Design Review
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December 9, 2008
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Albedo Change Mechanism
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AAA System Design Review
December 9, 2008
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Activity 3 Completion of Baseline Mission Concept

• Review previous work on the exploration and
  mitigation missions
• Students will be organized into the following
  technical specialty teams
• Albedo Change Subsystem
• Exploration Science Instruments Proximity
  Operations
• Telecom, Tracking CDH sub-systems
• Trajectory, Propulsion, Attitude Control System
• Structures, Thermal, and Power
• Budget and Scheduling
• Each team is to identify design holes in its
  area. These define the issues that are to be
  addressed in the concurrent engineering design
  session at NASA Ames
• Perform conceptual design at NASA Ames during
  the week of April 6, 2009

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Schedule of Activities

• Feb. 9 Kickoff meeting (All)
• Pass out Technical Specialty Group
  questionnaires (DCH),
• Solicit candidates for Program Manager
  Assistant Program Manager (DCH)
• Feb. 16 Review of design work to-date (DCH)
• Feb. 20 Return completed Technical Specialty
  Group questionnaires (AAA)
• Finish reviewing 426 and 402 Final Presentations
  (AAA)
• Feb. 23 Review thermal emission effects (DCH)
• Assign technical specialty groups (DCH)
• Elect PM and APM (AAA)
• Feb. 23-27 Brainstorm albedo change mechanism
  ideas (All)
• Formulate amalgamated mission concept (AAA
  technical teams)
• March 2 Select, albedo change device concept
  (All)
• NRC proposal outline assignment of
  responsibilities (DCH)
• March 9 Proposal progress review (All)
• Albedo change technology experiment definition
  (AAA albedo change team)
• March 16 Proposal Progress review (All)
• March 20 Submit proposal to NRC

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Schedule of Activities - Continued

• March 23 Define holes in mission design (AAA
  technical teams)
• March 23 - April 3 Work on albedo change
  technology experiment (AAA albedo team DCH)
• Finish defining design holes to be filled at
  NASA Ames design session (AAA technical teams)
• March 30 Progress review/ prep for NASA Ames
  (All)
• Complete technology experiment (AAA albedo team)
• April 6 Final prep for Ames visit
• April 8-10 Work at NASA Ames concurrent
  engineering design facility
• April 13 Baseline design results review (All)
• April 20 Final Presentation

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FINI
FINI
Alternate system offered was the Atlas 2 with
4.2m fairing at a cost of 84M Presenters were
uncertain about this. MIT presentation material
quotes a diameter of 1.49m