AERO 4730 Space Mission Design               
     

    Course Outline

    Space Links Page

    AERO 4740

    Class note links:

    Lecture 1

    Lecture 2

    Lecture 3

    Lecture 4

    Lecture 5

    Lecture 6

    Lecture 7

    Lecture 8

    Lecture 9

    Lecture 10

    Lecture 11

    Lecture 12

    Lecture 13

    Lecture 14

    Lecture 15

    Lecture 16

    Lecture 17

    Lecture 18

    Lecture 19

    Lecture 20

    Lecture 21

    Lecture 22

    Lecture 23

    Lecture 24

    Lecture 25

    Lecture 26

    Lecture 27

    Lecture 28

    Lecture 29

    Lecture 30

    Space Mission Design Lecture 10

    What's happening in space:

    Elektron Status - The crew performed troubleshooting on the Elektron throughout the week of September 13th in an attempt to recover functionality. Attempts to restart the unit and maintain sustained operations with Liquid Unit #7 were unsuccessful. Russian commission of designers recommended replacing #7 with #5. The Elektron was activated with #5 installed and operated for over 2.5 hours prior to being shut down before crew sleep. The safety community will resolve any issues next week prior to extended operations.

    Lab Flex Hose and Cover Installation - The crew completed the Lab Window flexhose and cover box installation activity. The crew depressurized the Lab Window inner pane volume and installed the spare flex hose that was flown up on 13P. A protrusion measurement was taken, for future reference, of the installed flex hose to determine how much it extends into the Window Observational Research Facility (WORF) volume. No leaks were detected from the window or the flex hose when the crew used the Ultrasonic Leak Detector for readings. The protective cover box that was assembled on August 17th was installed over the flex hose and final closeout photography was taken. The Lab Window Inspection was not accomplished and will be rescheduled.

    Crew Health Care System (CHeCS) Avionics Air Assembly (AAA) Fan Cleaning - The crew completed, for the first time, a thorough cleaning and vacuuming of the AAA fan duct behind the CHeCS rack. The Flight Engineer rotated the rack and removed the rear access panel to allow for the inspection and cleaning. Approximately one centimeter of dust and debris was cleaned off the fan duct. In addition, the Volatile Organic Analyzer's (VOA) N2 gas and electrical connections were demated in preparation for a future repair and replacement.

    Trade Studies         Link to trade study classroom example

  • Objectives
  • Know how to conduct an analytical trade study
  • Know how trade studies are used
  • Understand Technology Readiness Levels

    Technology Readiness Levels

  • Purpose is to meet all requirements in an optimal manner with minimum mass, volume and power while maximizing safety, reliability and mission success.
  • Formal, documented decision making methodology must be applied
  • Should be analytical
  • Results must be rational, objective and repeatable
  • Presentation must be easily understood

    Trade Study Methods

  • Many methods:
  • Equivalent Mass
  • Turn everything into mass to compare
  • Figure of merit
  • Assign values to everything
  • Advantage/disadvantage
  • (+ or - , relative scale: high, medium, low)
  • Weighted factors (my favorite)

    Weighted Factor Method

  • Define the problem, function or system needing comparison

    Example

  • CO2 removal
  • Identify candidate solutions
  • CDRA, Vozduch, LIOH, Molecular Sieve, etc
  • Identify trade variables
  • Mass, power, volume, TRL, cost, reliability, etc
  • Create a specification sheet for each technology
  • Find performance, physical, cost, etc data
  • Historical information is best
  • Testing may be necessary
  • Establish quantification scale
  • Set representative scale 1-10 with 10 being best
  • Normalize parameters – for example:
  • Mass: 0-25 kg = 10, 25-50 kg = 9, 50-75 kg = 8, …..
  • Cost: 0-$100K = 10, $100K-200K = 9, …..
  • etc
  • Determine weighting factors and rationale
  • Cost = x 2.0 Budget is constrained
  • Power = x 1.0 No power limits – nuclear reactor
  • Calculate value for each candidate solution
  • Highest number is optimal solution
  • Check if answers are rational
  • Document clearly

    Trade Study Example:
    I need to commute from Texas to Alabama and want to decide the best way to do it.

    Let’s use the weighted factor method:

  • 1. Define the problem, function or system needing comparison:
  • Transportation means for commuting
  • 2. Identify candidate solutions:
  • Drive
  • Fly my experimental airplane
  • Fly new, more capable airplane
  • Take a commercial flight
  • 3. Identify trade variables:
  • Initial cost
  • Operating cost
  • Time
  • Reliability
  • TRL
  • Hassle (they can be soft or subjective)
  • Safety
  • Others?
  • 4. Create a spec sheet for each technology
  • 5. Establish quantification scale: Set scale as 1-10 with 10 being best
  • Normalize parameters
  • 6. Determine weighting factors (it is subjective!)
  • 7. Calculate values for each candidate solution:
  • (Weighting factor) x (Normalized value) = Total

    Compare numerical totals to arrive at the trade study conclusion:
    Buy a new, more capable airplane