Team Force FieldLeslie ChapmanScott CornmanAdam Johnson

Richard MargulieuxBrandon Phipps

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

Launch Vehicle

Piggyback with Government

Piggyback with Private

LV

Use exclusive LV

Trade Tree

Propulsion Earth escape

Rendezvous with Apophis

Chemical Low Thrust

Solar Sails Electrical

Power

Solar Fuel Cells Nuclear RTG

Trade Tree

Electric

Cold Gas

Chemical

Momentum Devices

Hall’s Effect Thrusters

PPT BipropellantMono

AugmentedTraditional Reaction WheelCMG

3-Axis Attitude and Translational Control

Trade Tree

Proximity Operations

Complete LanderComplete Stand-offCombination of stand-off

to deploy

Trade Tree

Trade Tree

OrbitStand-off

Complete Stand-off

MultipleSingle MultipleSingle

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

Trade Tree

Complete Lander

MultipleSingle

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

Questions ?