Mission Analysis March 2004

Frontpage: 

Frontpage Mission Analysis & System Engineering Per Lundahl Thomsen, Programme Manager, E-mail: plt@dsri.dk Introduktion Mission Analysis in General Terms System Enginering Tools Example 2 - Rømer

Introduction – What is Mission Analysis ?: 

Introduction – What is Mission Analysis ? ”Mission analysis is a structured method of ensuring that the mission success criteria's are clear and well understood.” & ”Mission analysis ensures, that the mission fulfils the overall success criteria's and at the same time stays within the project boundary conditions technical, political and financial.” & ”Mission analysis define the on-board subsystems configuration and basic subsystem requirements.”

Introduction – where would we be without Mission Analysis: 

Introduction – where would we be without Mission Analysis From ”Understanding Space” by Jerry Jon Sellers

Example 1 - Building a Backyard Deck: 

Example 1 - Building a Backyard Deck I need a nice deck or patio to put the BBQ and a place to relax in the sun I really have to resist the urge to drive to the hardware store to buy a load of lumber and start filling the garden with sawdust. I say to myself........ Think first then act. I carefully define what I really need before I drive down to the hardware store. - How much money do I have - How big do I want it to be. How big does my wife want it to be - What colour should it be What kind of materials and tools to I need How long time do I have to built it. Can I buy it off-the-shelf What is the cost If the cost is too high ???? Can I do it in time for the garden party next week ??? My wife comes a couple of days later and says I also want a nice hot tub – right there.......Hmm.. Again I have to go back and see if I can accommodate a tub within the constraints...........if you respect your wife's wish that is ! When I am reasonably certain I buy what I need and start building the Deck

Initial Considerations – Mission Requirements and Constraints: 

Initial Considerations – Mission Requirements and Constraints During the FIRST steps of the Space systems engineering process we define mission requirements and constraints. This involves Define Mission Statement Incl. State the mission objective – why we do the mission Identify mission users – who will benefit from or use the information produced by the mission Create the operations concept – how will all the mission elements fit together Identify mission constraints (Cost, schedule and performance) DOCUMENT THIS IN A MDD (Mision Definition Document)

Initial Considerations – System Requirements: 

Initial Considerations – System Requirements During the SECOND step of the space systems engineering process we derive the system requirements Review the constraints on mission architecture (Launch vehicle, orbit, operations, lifetime etc.) Identify and characterize the mission subject – (eg. ”what” will the spacecraft instrument complex (payload) do ?) Derive payload requirements Derive orbital requirements Determine basic spacecraft size and mass (envelope) Identify potential launch vehicles Derive operations network requirements (Groundstations). DOCUMENT THIS IN THE SRD (SYSTEM REQUIREMENTS DOCUMENT)

Initial Considerations - Subsystem definition: 

During the THIRD step of the space systems engineering process we start defining the subsystems, and after a few iterations of the requirements etc, the design can begin. Define ACS concepts (based on pointing, positioning and stability requirements) Define reduncdancy concepts. Define onboard subsystems (EPS, COM, CDH, Payload computer, On board SW, ACS etc. Perform data flow analysis Determine ground coverage and communications concept link budget Determine needed power and power output analysis Define thermal requirements and perform initial analysis Determine structural requirements and perform initial analysis Analyse radiation environment DOCUMENT THIS IN THE SRD or define Subsystem Requirements Documents RE-ITERATE ALL Initial Considerations - Subsystem definition

Mission Analysis – Flow: 

Mission Analysis – Flow From ”Understanding Space” by Jerry Jon Sellers

Mission Analysis - Iterations: 

Mission Analysis - Iterations From ”Understanding Space” by Jerry Jon Sellers

Slide10: 

System Engineering Tasks on Small Satelites Monitor The Design Process with the requirements in hand Ensure Project Communication incl. - External technical communication - Internal technical communication

Slide11: 

Satellite on-board systems Functions indicated How shall these functions be implemented? How shall they be linked together? (Interfaces) What kind of tasks are assigned to each function? System Engineering Tasks on Small Satelites

Slide12: 

Reduncdancy concepts. (Cubesats should be a single string satellite) Define and Maintain Data flow analysis Incl.: Definition of Data bus, Calc. of mass memory, Calc. of proccessing power and Def. of Protocols. Agree on Timing Concept Definition of Power bus (Power distribution concepts, grounding concepts) BUDGETS: - Define and Maintain Power Budget Incl. power output analysis - Define and Maintain Mass Budget - Define and Maintain Link Budget Define and Maintain Subsystem and System Interfaces: Electrical, SW, Mechanical and Thermal. System Engineering Tasks on Small Satelites – Page 1 of 2 - Use ICD’s

Slide13: 

System Engineering Tasks on Small Satelites – Page 2 of 2 Define and Maintain Satellite Interface design eg. test equipment & Launch vehicle Get system permissions (Frequencies, Spacecraft ID’s, export licenses etc.) Define baseline for satelite operations Define baseline for system test procedures and ensure coherence with operations and control systems. Participate in Satellite integration and Test Test Test Test Test ENSURE A CONTINOUS SYSTEM ENGINEERING CORE TEAM

Design and Analysis Tools: 

Design and Analysis Tools Design and analysis tools include computerbased and other techniques to calculate subsystem specifications and simulate trade-offs. Examples include: Spreadsheet (eg mass calculations, power output, link budget) Mathcad, Matlab, IDL for simulation of eg. ACS algorithms, power output and link budgets CAD Designtools etc for mechanical design. Eg Autocad, Mechanical desktop etc. Structural & Thermal design tools (Ansys, Ideas, NASTRAN, ESA-RAD/ESA- TAN) STK ”Satellite Tool Kit” for orbit analysis, ground tracks, pointing, visualisation, power output, link budgets operation implications Orbit analysis Nova for windows (WWW.NLSA.COM), realtrack Radiation environment analysis (www.spenvis.oma.be/spenvis.) Just remember .........”garbage in ...means garbage out” ....always have a sound understanding of the input and of the results.

Basic Rule 1 - Keep It Simple......Stupid (KISS): 

Basic Rule 1 - Keep It Simple......Stupid (KISS) KISS

Basic Rule 2 – Keep track of interfaces: 

Basic Rule 2 – Keep track of interfaces Keep track of interfaces USE ICD’S

Slide17: 

Basic Rule 3 – Make a plan Make a plan with appropriate milestones

Basic Rule 4 – Have fun: 

Basic Rule 4 – Have fun HAVE FUN &