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MECH 372 / ENGR 372
Space Systems Design and Engineering II
 
Assignment #1 Solutions
 
 
Objective: The objective of this assignment is to demonstrate an understanding of the basic motivations, structure, characteristics, and issues relating to space missions. 
1. Text Problem 1.1-1
global perspective
unobscured view above atmosphere
microgravity (free-fall) environment
resources
unique exploration challenges as final frontier

2. Text Problem 1.1-2

space-based communications
remote sensing satellites
navigation satellites
science/exploration satellites

3. Text Problem 1.2-3

objective
users or customers
operations concept

4. Text Problem 1.2-4

spacecraft
orbit
launch vehicle
mission operations system
mission management and operations

5. Text Problem 1.2-5

payload - portion of satellite that performs the mission
bus - provides support to payload... the "housekeeping" functions

6. Text Problem 1.2-11.  Do parts (a) and (b), but note that defining the "mission" means that you should describe all of the topics as specified in Problem 1.2-3.

Note - this is an interesting case of a one space mission (the Shuttle flight) used to support another mission (the observation satellite).  It is important to distinguish between these systems and missions.

(a) - mission (objectives, users, ops concept) of Shuttle: to deploy a satellite for the "owners" of that satellite, using the standard Shuttle launch infrastructure, an LEO orbit, and the Shuttle ground network and ops/management teams

(b) - mission (objectives, users, ops concept) of satellite: monitor atmosphere for atmospheric scientists using a Shuttle/IUS launch system, a particular orbit appropriate to the mission, and the TDRS telemetry network and data teams

7. Text Problem 2.1-2.  Forgive me, but this is such a great question given SCU's Jesuit heritage.  Challenge - I would be very interested if any of you would like to do a little bit of research into the Jesuit reaction to Copernicus's work. If done well, I would give you 3-5 min in class to present your findings.

Copernicus's heliocentric theory challenged humanity's view of itself, particularly wrt religious beliefs, given the proposition that the Earth was not the center of the universe.  In addition, there was some scientifically-based issues, such as the lack of evidence of Earth's movement, the issues with continuing to believe in circular orbits, etc.

8. Text Problem 16.1-1.  Comment on each

Globalization - space becoming a global activity w/ 20+ countries having national space programs

Commercialization - space activities are beginning to be commercially motivated rather than simply being government initiated

Capital market acceptance - investment capital is being invested due to potential commercial payoffs

Emergence of new industry leaders - several niche markets exist with established leaders

9. Text Problem 16.2-6.

Promote national image and policy objectives
Enhance security
Advance science and technology
Support national industries

10. Text Problem 16.3-9

Lifecycle cost is the total cost to perform a mission, to include design, manufacture, launch, operations
11.  Benchmark the IKONOS, GPS, SpaceWay-1, and GeneSat-1 missions by filling in the following table (you should be able of filling out the vast majority of this table).  Additional references in addition to the textbook include:
  IKONOS GPS SpaceWay-1 GeneSat-1
Mission objective Provide commercial 1-meter resolution imagery Provide radio navigation signals for positioning systems Direct broadcast of high def TV Demonstrate advanced biological processing capabilities via an E. coli genetics experiment
Mission users / customers farmers, city planners, environmental scientists, etc. military, commercial, etc DirecTV customers Ames astrobiologists and technologists
How do users get their products / services web order via purchased receiver via their own small dish web links
Owner / operator Geoeye US military DirecTV Ames/SCU
# Satellites in the space system 1 24 primary 1 but part of larger 'constellation' (3 SpaceWays) 1
Launch date 9/24/99 various since 1978 4/26/05 12/16/06
Launch vehicle LM Athena II Delta II SeaLaunch Zenit OSC Minotaur
Orbit Polar (98.1 inclination), circular (e=.00013), sun-synch, 400 mi (681 km) medium orbit (~20,000 km) in 6 55 deg orbital planes for global coverage geosynch 22,300 mi 40 inclination, near circular, 410 km altitude
Design Life 7 yrs 7.5 yrs 12 yrs 21 day experiment - lifetime ~ months
Spacecraft Mass 1800 lbs (820 kg) 1900 lbs 13,400 lb (~6,000 kg) 6.8 kg
Spacecraft Size 1.83m x 1.57m hexagonal volume 17 ft long w/ panels 16.6 ft x 11 ft x 10.6 ft stowed; 134 ft long x 24 ft with solar arrays and comm ant deployed 10cm x 10cm x 30cm
Payload Multispectral and panchromatic camera systems consisting of telescope, camera and digital processing unit Highly accurate clocks and a transmission system to broadcast navigation messages Ka-band comm transmitter Microfluidic system for supporting biological growth, with optical instruments for measuring flourescence
Bus Power 1.5 kW via deployed panels 710W 12.3 kW 4-5W
Bus Pointing Components 3-axis stabilized using 2 star trackers, sun sensors, 4 reaction wheels 3-axis via reaction wheels 3-axis Passive magnets and hysteresis rods
Bus Communication Systems 2 and 8 GHz s-Band (~2.4 GHz) and UHF; L-band (1.2 and 1.5 GHz) nav broadcasts Ka-band and broadband 2.4 GHz cmd and UHF beacon
Example data product (provide a web link if possible)
http://www.geoeye.com/
gallery/default.htm
Position solution computed by a commercial receiver TV shows
http://genesat1.engr.scu.edu/
dashboard/index.htm
Impact / contribution 1st commercial hi-res satellite imaging system Fully functional global navigation system A satellite in the largest commercial segment of the space industry Cutting edge technology demonstration for autonomous in-situ spaceborne biology