1. SFINX Surveying 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

2. The Planet Mars SFINX Surveying Flying IN-situ eXplorer
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!!!

3. Mars Exploration Vehicles
SFINX
Surveying 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

4. SFINX
Surveying Flying IN-situ eXplorer
Structures

5. SFINX Surveying Flying IN-situ eXplorer TAKE OFF FLIGHT LANDING
No Improved Surfaces
Rocky and/or Sandy Conditions
FLIGHT
Finite Flight Duration
Stability vs. Maneuverability
LANDING
Forward Momentum
Controllability

6. SFINX Surveying Flying IN-situ eXplorer FLIGHT TAKE OFF LANDING
L = W = ½ ρ V2 S CL

7. SFINX X(s) G(s) Y(s) Surveying Flying IN-situ eXplorer
Propulsion System
X(s)
G(s)
Y(s)

8. Propulsion System: Inputs
SFINX
Surveying Flying IN-situ eXplorer
Propulsion System: Inputs
Input 1:
Specific energy of CO2 fuel in tank

9. Propulsion System: Inputs
SFINX
Surveying Flying IN-situ eXplorer
Propulsion System: Inputs
Input 2:
Heat supplied by a heater

10. Propulsion System: Transfer Function
SFINX
Surveying Flying IN-situ eXplorer
Propulsion System: Transfer Function
Variables
Throat diameter: d*
Affects thrust & exhaust time
Tank volume: V
Affects total impulse, weight,and required heat input
Area ratio: AE/A*
Affects flow properties:
ME, AE/A*, PE/PO, TE/TO

11. Propulsion System: Outputs
SFINX
Surveying Flying IN-situ eXplorer
Propulsion System: Outputs
Impulse: tt
Fuel mass: m(t)
Maximum vehicle height:
Solved by integrating velocity:

12. Propulsion System: Height
SFINX
Surveying Flying IN-situ eXplorer
Propulsion System: Height

13. SFINX Surveying Flying IN-situ eXplorer Flight Controls
Vehicle Controls
Navigation
Obstacle Detection and Avoidance

14. SFINX Surveying 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

15. SFINX Surveying 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

16. Obstacle Detection and Avoidance
SFINX
Surveying 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

17. SFINX Surveying 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.

18. SFINX Surveying 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

19. SFINX
Surveying Flying IN-situ eXplorer
Questions?