SFINXSurveying Flying IN-situ eXplorer

Old Dominion University

Mars Exploration Vehicle

Senior Design Project

Mentors:

Dr. Robert Ash & Dr. Colin Britcher

Students:

John Miller, David Covington, Bradley Dupont,

Brian Meagher, Nelson Gosnell, Grant Jennings

SFINXSurveying Flying IN-situ eXplorer

The Planet Mars

• Temperature: -207 F to 68 F, with an average of -81 F

• Pressure: 6 to 10 millibars

(0.06% Earth pressure)

• Highest to Lowest point 40 km

• Atmosphere: 95.3% CO2

Evidence of a very different past!!!

SFINXSurveying Flying IN-situ eXplorer

Mars Exploration Vehicles

Current: Slow, delicate, inefficient, will take 1 million years to cover the surface

Needed: Fast, robust, adaptable, reusable, with utilization of Martian resources.

Answer: Build on previous research to design an aircraft using CO2 for propulsion

SFINXSurveying Flying IN-situ eXplorer

Structures

SFINXSurveying Flying IN-situ eXplorer

TAKE OFF

No Improved Surfaces

Rocky and/or Sandy Conditions

FLIGHT

Finite Flight Duration

Stability vs. Maneuverability

LANDING

Forward Momentum

Controllability

SFINXSurveying Flying IN-situ eXplorer

TAKE OFF

FLIGHT

LANDING

L = W = ½ ρ V2 S CL

SFINXSurveying Flying IN-situ eXplorer

Propulsion System

G(s)X(s) Y(s)

SFINXSurveying Flying IN-situ eXplorer

Propulsion System: InputsInput 1:

Specific energy of CO2 fuel in tank

SFINXSurveying Flying IN-situ eXplorer

Propulsion System: InputsInput 2:

Heat supplied by a heater

Required Heat Input

dQ(t)/dt = 478802e-0.4646t W

R2 = 1

0

50000

100000

150000

200000

250000

300000

350000

400000

0.000 2.000 4.000 6.000 8.000

Time (s)

Hea

t S

up

pli

ed (

W)

Propulsion System: Transfer Function

Variables

Throat diameter: d*Affects thrust & exhaust time

Tank volume: VAffects total impulse,

weight,and required heat input

Area ratio: AE/A*Affects flow properties:ME, AE/A*, PE/PO, TE/TO

SFINXSurveying Flying IN-situ eXplorer

Isothermal Model of CO2 RocketThrust vs Time

Thrust = 3447.3e-0.4646t - 0.02471 N

R2 = 1

0.00E+00

5.00E+02

1.00E+03

1.50E+03

2.00E+03

2.50E+03

3.00E+03

3.50E+03

4.00E+03

0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000

Time (s)

Thru

st (N

)

SFINXSurveying Flying IN-situ eXplorer

Propulsion System: OutputsImpulse: tt

Fuel mass: m(t)

Maximum vehicle height:Solved by integrating velocity:

Thrust vs Time

Thrust = 3447.3e -0.4646t - 0.02471 N

R2 = 1

0.00E+00

5.00E+02

1.00E+03

1.50E+03

2.00E+03

2.50E+03

3.00E+03

3.50E+03

4.00E+03

0.000 1.000 2.000 3.000 4.000 5.000 6.000 7.000

Time (s)

Thru

st (N

)

SFINXSurveying Flying IN-situ eXplorer

Propulsion System: Height

SFINXSurveying Flying IN-situ eXplorer

Flight Controls

– Vehicle Controls

– Navigation

– Obstacle Detection and Avoidance

SFINXSurveying Flying IN-situ eXplorer

Vehicle Controls• Need attitude readings

• Pitch, Roll, Yaw, velocities, rates• Need both absolute and wind-relative•Wind-relative measured via differential pressure readings

• Pitot-static tubes, five-hole probes, etc.•Absolute values measured via corrected inertial sensors

•Horizon readings, radar or laser velocity readings from the ground

SFINXSurveying Flying IN-situ eXplorer

Navigation

–Accurately move from location to location–Inertial system primary navigation

Have to correct for inertial drift–Celestial navigation–Landmark navigation

–Corrections may not be necessary

SFINXSurveying Flying IN-situ eXplorer

Obstacle Detection and Avoidance

– High probability of landing on rocky terrain– Will use radar to measure terrain “suitability”

• Does not identify individual objects• Very high speed

SFINXSurveying Flying IN-situ eXplorer

Power System• Solar Cells

– Light Spectrum– Scattering of light– Temperature– Solar Cell

Characteristics– Available Solar

Energy

• Batteries– 180 Wh/kg– 6.7 kg to store

power gathered in one day.

SFINXSurveying Flying IN-situ eXplorer

Communications

Atmel SRAM based FPGA:Capable of functioning in harsh Martian environment,Tested at over 300krad, -55 to +125 C

Micro-Transceiver: developed for low weight, low power Mars operations

Capable of –100 to 25 C

Over 100 krad hardening

UHF: half duplex

SFINXSurveying Flying IN-situ eXplorer

Questions?