ASTE330 Term Project
Presentation and Report Due Last Day of class
250 pts total
(Report is 175pt, in class presentation is 50 pts, 25 pts for Novel Concepts)
Overview
Design a mission to Saturn using the parameters in Tables 1 to 3 and the requirements
below. You may work in teams of up to 3 people. Each member of the team will receive
the same grade. Each team member must also present their portion of the work at the
class presentation. Feel free to use NASA’s Cassini Spacecraft as a starting point or justification for any
selections you make. However you may not copy it. You may use in class or SMAD values for any
parameters that are not directly calculable (efficiencies, degradations, specific masses, etc.). Please
provide the reference and/or justification. When you do your calculations feel free to use
your prior HW solutions as the template and update the values for Saturn and your
specific spacecraft parameters.
Requirements / Assumptions
The only requirements are as follows:
1. Place the spacecraft in a 400 km circular orbit around Saturn. Half way through the mission
change the inclination of the orbit to enable a new science goal.
2. Mission Duration in orbit around Saturn is 5 Earth years.
3. The propulsion system shall be chemical (not electric).
4. The delta V for the first burn of the Hohman transfer is provided by the Launch Vehicle Upper
Stage. The spacecraft only needs to perform the second burn with its propulsion system.
5. The science payload shall not exceed 100 kg
6. Spacecraft shall be capable of transmitting at least 100 Mbps.
7. The primary structure shall be designed to meet the requirements in Table 3.
8. The spacecraft shall use an RTG, MMRTG, or ASRG as its primary power source and have a
backup battery sized to operate spacecraft subsystems for at least 24 hours.
Required Calculations
You must fill out all entries in Table 4 in the units provided (to be provided separately).
This will allow a calculation of your mission subsystem sizing for grading and if you
need help along the way. You must at a minimum perform the calculations and
document the assumptions for the following 11 items in a typed format. All of these
calculations were (or will be) from your homework problems. Math calculations can be
hand written or typed. The more work you show the more partial credit you can get.
1. Overall description of the mission including: (10 pts)
a. Overall description of the spacecraft
b. Level 1 mission requirements (at least 3)
c. Overall mass and power budget
a. This should include all subsystems and the payload
d. Drawing of spacecraft (hand sketch or computer) showing placement of all subsystems and
payload
2. Mission Design (20 pts)
a. Short description of the mission design
b.
c.
d.
e.
f.
g.
Hohman transfer from Earth to Saturn
Trip time to destination
Maximum distance from sun (defines minimum power generation)
Maximum distance from Earth versus (defines maximum space loss)
Thermal heat flux environment over an orbit (solar, IR, albedo)
Propellant budget calculation (after you have done parts 3 and 4)
3. Chemical Propulsion Subsystem (20 pts)
a. Type of thruster and propellant you selected
b. Define To and Po
c. Nozzle area ratio calculation or selection
d. Exit pressure and Mach number calculation
e. Mass flow rate calculation
f. Specific Impulse calculation
g. Thrust calculation (Pa=0 but you still need to calculate Pe*Ae term)
h. Propellant Mass for cruise
i. Propellant Mass for ACS (if primary ACS or for momentum wheel dumping)
j. Main engine burn time only for major maneuvers
4. ADCS Subsystem (20 pts)
a. Short description of the subsystem you selected including hardware for attitude determination
and control
b. Choose spin or three axis stabilized
c. Calculate disturbance torques and size the system accordingly (see Table 1 for Saturn specifics)
d. Mass and power estimate for the ADCS (you may use SMAD or numbers from other
representative spacecraft)
5. C&DH Subsystem (10 pts)
a. Define mass, power, volume based on complexity (SMAD table)
6. Power Subsystem
a. Short description of the subsystem you selected
b. Calculate solar irradiance, albedo, and IR components of q_ext at Saturn. The hot and cold case
are related to distance from the sun for solar and albedo.
c. Size RTG for operation at Saturn (mass, BOL and EOL power).
a. Determine EOL performance on orbit
b. Determine battery size and type of battery
c. Determine mass of the array and battery
7. Thermal Subsystem (20 pts)
a. Short description of the subsystem you selected
b. Determine the allowable flight temperature range
c. Calculate solar irradiance, albedo, and IR components of q_ext at Saturn. For the cold case
assume you are in the eclipse period.
d. Size the radiator for worst case hot
e. Size the survival heaters for worst case cold
8. Primary Structure Subsystem design using the provided launch vehicle
parameters (Table 3). Use Aluminum for the primary structure material. It is fine
to use an evenly distributed mass assumption but the placement of the various
hardware should be consistent with that.
a. Short description of the subsystem you selected (including shape)
b. Load calculations for ultimate stress, yield stress, buckling stress, and
f. natural frequency
c. State Shape and AMOI
d. Discuss placement subsystems within the overall spacecraft
9. Payload subsystem
a. Define at least three science instruments including their mass, power, and
data rate (feel free to use instruments from other missions)
b. Define one scientific objective for each instrument.
10. Telecommunications system
a. Short description of the subsystem you selected
b. Frequency Band
c. Antenna size, type, efficiency
d. Transmitter power
e. Maximum payload data rate (from part 9)
f. House keeping data rate
g. Link Budget for maximum distance from Earth
11. Description of the sensitivities of the space craft to the space environment around Saturn
a. Calculate the total radiation dose based on the thickness of your structure
a. (assuming Al)
b. Calculate flux of MM versus particle size
c. Design choices you have made to mitigate spacecraft charging
d. Brief discussion of materials that you have selected and how that may
e. affect contamination, radiation degradation, thermal performance, etc.
Table 3. Atlas V Class Launch Vehicle Parameters
Lateral Natural Frequency (Hz)
8
Axial Natural Frequency (Hz)
15
Axial Load Factor
7
Lateral Load Factor
3
Maximum Fairing Diameter (m)
4
Maximum Fairing length (m)
10
More info on Saturn here.
http://nssdc.gsfc.nasa.gov/planetary/factsheet/saturnfact.html
More info on the launch vehicle here.
http://www.spacelaunchreport.com/atlas5.html
Saturn Bulk parameters
Saturn
Earth
Ratio (Saturn/Earth)
Mass (1024 kg)
568.36
5.9726
95.159
Volume (1010 km3)
82,713
108.321
763.59
Radius (1 bar level) (km)
Equatorial
60,268
6,378.1
9.449
Polar
54,364
6,356.8
8.552
Volumetric mean radius (km)
58,232
6,371.0
9.140
Ellipticity (Flattening)
0.09796
0.00335
29.24
Mean density (kg/m3)
687
5,514
0.125
Gravity (eq., 1 bar) (m/s2)
10.44
9.80
1.065
Acceleration (eq., 1 bar) (m/s2)
8.96
9.78
0.916
Escape velocity (km/s)
35.5
11.19
3.172
GM (x 106 km3/s2)
37.931
0.3986
95.16
Bond albedo
0.342
0.306
1.12
Visual geometric albedo
0.47
0.367
1.28
Visual magnitude V(1,0)
-8.88
-3.86
Solar irradiance (W/m2)
14.90
1,367.6
0.011
Black-body temperature (K)
81.1
254.3
0.319
Moment of inertia (I/MR2)
0.210
0.3308
0.635
J2 (x 10-6)
16,298.
1082.63
15.054
Number of natural satellites
62
1
Planetary ring system
Yes
No
Orbital parameters
Semimajor axis (106 km)
Sidereal orbit period (days)
Tropical orbit period (days)
Perihelion (106 km)
Aphelion (106 km)
Synodic period (days)
Mean orbital velocity (km/s)
Max. orbital velocity (km/s)
Min. orbital velocity (km/s)
Orbit inclination (deg)
Orbit eccentricity
Sidereal rotation period (hours)
Length of day (hrs)
Obliquity to orbit (deg)
Saturn
1,433.53
10,759.22
10,746.94
1,352.55
1,514.50
378.09
9.68
10.18
9.09
2.485
0.0565
10.656*
10.656
26.73
Earth
Ratio (Saturn/Earth)
149.60
9.582
365.256
29.457
365.242
29.424
147.09
9.195
152.10
9.957
29.78
0.325
30.29
0.336
29.29
0.310
0.000
0.0167
3.383
23.9345
0.445
24.0000
0.444
23.44
1.140
Saturn Observational Parameters
Distance from Earth
Minimum (106 km)
1195.5
Maximum (106 km)
1658.5
Apparent diameter from Earth
Maximum (seconds of arc)
20.1
Minimum (seconds of arc)
14.5
Mean values at opposition from Earth
Distance from Earth (106 km)
1277.42