team force field leslie chapman scott cornman adam johnson richard margulieux brandon phipps
TRANSCRIPT
Presentation Outline
Introduction Mission Objectives Background Mission Mission Profile
Trade Tree Spacecraft
Mission Profile Lander Orbiter Communication Link and
Command & Data Handling Advantages
Introduction
Mission Objectives• Primary Objectives
– Determine the trajectory of Apophis– Determine the seismology of Apophis
• Secondary Objectives– Laser mapping of Apophis– Close imaging of Apophis
Introduction
• Galileo– Successful approach of 951 Gaspra, 243 Ida and Dactyl– Solid state imager, Near IR spectrometer
• Dawn– 3 DS1 Xenon Ion Engines, 3 Visual sensors, Visual and IR spectrometer,
Gamma Ray and Nuetron spectrometer• Phobos 1,2
– Unsuccessful study of Phobos and Deimos– Two landers, hopper, long-lived, spectrometer, seismometer,
penetrometer– Orbiter houses IR, visual, Near IR spectrometer, Gamma, X-ray sensors
• Deep Impact– Successful flyby and impact event of comet 9p/Tempel, extended
mission to 85P/Boethin– High Resolution Imager, Medium Resolution Imager, Impactor Targeting
Sensor, Infrared Spectroscope– 650kg/370kg impacter
Past Missions
Introduction
• NEAR Shoemaker– Successful orbit and landing on Eros, communicated for 2 weeks before being
shutdown– Mass: 487kg– Approach Distance: 200km, 35km, 5-6km, 2-3km, land at 1.5-1.8m/s– Reaction wheels and hydrazine thrusters, 1800 W solar power, Ni-Cd battery
pack, IMU, gyros, sun sensors and star tracker– X-ray/gamma ray spectrometer, Near-infrared imaging spectrograph, Multi-
spectral camera fitted with a CCD imaging detector, Laser rangefinder, Magnetometer, Radio science experiment to determine gravity field
• JAXA Hayabusa– Successful heliocentric orbit near and two close approaches to 25143 Itokawa,
failed deployment of MINERVA, on return trajectory to Earth– Mass: 380kg (MINERVA: 591g)– Approach Distance: 20km, 44m, ?– 4 Xenon Ion Engines, Reaction wheels (failed on orbit), thrusters– Multiband imaging camera, Laser altimeter, Near-infrared spectrometer, X-ray
spectrometer
Past Missions
Trade Tree
Propulsion Earth escape
Rendezvous with Apophis
Chemical Low Thrust
Solar Sails Electrical
Electric
Cold Gas
Chemical
Momentum Devices
Hall’s Effect Thrusters
PPT BipropellantMono
AugmentedTraditional Reaction WheelCMG
3-Axis Attitude and Translational Control
Trade Tree
Trade Tree
Partial Deployment
Main Lander with Orbiting Link
Main Orbiter with
Lander(s)
Orbiter- Radios
-Camera
-Solar Panels
Lander― Transponder― Camera― Laser mapping device― Seismology detector― Radio― Solar Panels
Orbiter- Radios
- Transponder
-Camera
-Laser mapping device
-Solar Panels
Lander-Transponder
-Seismology detector
-Radio
-Solar Panels
Landing Systems
Barbed Attachment Hooks
ImpactorHarpoon and
Winch
Skids
Pyramid Design
Cubic Design
Trade Tree
Gossamer Net
Mission Critical Components
Tracking Architecture
Transponder(s) on Lander(s)
Transponder on Stand-off
Vehicle
Seismic Measurement Method
Active Ping and Listen
Passive Seismomete
r
Trade Tree
System Description
• Orbiter with Landers– Rendezvous with Apophis– Landers deploy to Apophis– 200-300 kg to Earth Orbit– ~100 kg at Apophis
System Description
• Earth Operations– Launch– Start-up and system checkout
• Trajectory– Plane change and escape velocity burn– Orbit transfer burn and course corrections
• Initial Apophis Operations– Stand-off at safe distance– Initial imaging, mapping, data transfer– Landing site selection from Earth
• Apophis Close Approach and Deployment– Incremental Approach to Apophis– Hover above Apophis surface, deploy landers– Orbiter return to heliocentric orbit– Landers deploy, gather initial data and transfer
• Earth Close Approach Event– Tracking with transponders– Orbiter to Earth and Apophis attitudes– Shifting morphology seismometer readings– Data transfer to Earth
Mission Profile
The Landing Problem
• Close approach of Apophis by orbiter• Spring loaded deployment of landers
Orbiter
Apophis Surface
Lander Sub-systems and Instruments
Step 1 Step 2 Step 3
• Landers– Open Tetragon to automatically orient– Equipped with:
1) Shallow pitch drill2) Acoustic equipment3) Cross-link radio4) Transponder5) Solar panels
Orbiter Subsystems
• Orbiter Systems– Power: Solar Panels
• Stable, established source of energy
• No consumables• Limited Degradation
• 1 kW requires ~7 m2
Orbiter Subsystems
• Reaction Wheels– Minimum of 3 reaction wheel assemblies– Provide X,Y, & Z attitude control– Controlled from 1 control box
• Pulsed Plasma Thruster– Attitude control, low thrust maneuvers– Solid Propellants
– High Isp, low impulse
– Uses ionized, accelerated plasma
1. Energy Storage Unit
2. Ignitor
3. Fuel Rod
4. Plasma Accelerator
Orbiter Instruments
• Laser mapping device• Transponder• Star Tracker• IMU, Gyros• Radios
– Crosslink with landers– Uplink– Downlink
• High bandwidth• Low bandwidth
• Imagers– Near IR– Visual
Communication Link and Command & Data Handling
Communication Link• Uplink radio• Downlink radio• Cross-link• Transponders
Earth
Command and Data Handling• Solid state storage devices• Semi-autonomous (command to begin
programmed events)• Ability to upload new command sets
Advantages: Landing System
• Redundancy: multiple landers can be deployed • Landing orientation does not matter• Hooks on all vertices discourage rebound off
surface• Robust landing structure to protect delicate
equipment• Spring loaded deployment results in low reaction
force on orbiter• Optical equipment remains on orbiter to avoid
impact of landing
Advantages: Orbiter Subsystems
• Solar Panels– Proven technology– Stable energy source
• Semi-autonomous command– Allows for actions with limited
communication– Flexibility
• Communications Link– Constant line of sight
• Imaging– B/W for low data rates– Near IR for composition data
• 3-Axis Control– Reaction Wheels
• Small, prebuilt assemblies• No consumables
– PPT• Small form factor• High Isp
• Low Impulse
• Tracking Scheme– Constant line of sight– Large power source– Simple transformations