1 Space Systems Overview CDR David D. Myre

2 What is a Space System?  Ground Spaceflight Operations Payload Operations (Can be separate) Payload Data Processing (Hubble)  Space Spacecraft Supporting Craft (TDRSS, Progress)  Launch Launch Vehicle Integration Launch Operations

3 Tracking and Data Relay Satellite System

4 What Does a Spacecraft “Look” Like?  Spacecraft “appearance” is almost always function over form  Physical constraints: Launch Vehicle  Payload Fairing  Loads Power Required Vehicle dynamics  Mission Trajectory  Pointing HST

5 Spacecraft Description  Spacecraft have two main parts: Mission Payload Spacecraft Bus  Mission Payload A subsystem of the spacecraft that performs the actual mission (communications, remote sensing etc.) All hardware, software, tele- communications of payload data and/or telemetry and command There can be secondary payloads  Spacecraft Bus  Hardware & software designed to support the Mission Payload Provides  Power  Temperature control  Structural support  Guidance, Navigation May provide for telemetry and command control for the payload as well as the vehicle bus Mars Global Surveyor

6 TDRSS 1-7 Specifications Dimensions: 45 feet wide / 57 feet long Weight: 5000 pounds Design Lifetime: 10 years Power (EOL): 1800 watts Services: KU & S-Band services Launch Vehicle: Space Shuttle Orbit: Geosynchronous

7 Spacecraft Bus Subsystems  Electronic Power System (EPS)  Position and Attitude Control: Attitude Control System (ACS) Guidance, Navigation and Control (GNC) Propulsion (OK, we’ll call it “Prop”)  Command and Data Handling (C&DH): Data Handling (Mission Data) Telemetry, Tracking and Command System (TT&C)  Thermal Control System (TCS)  Structural Subsystem

8 UHF Follow-On  Features Each satellite provides 39 channels for Ultra High Frequency (UHF) two-way communications, Super High Frequency (SHF) anti-jam, command and tracking link and communication uplink for fleet broadcast over UHF Uses S-band communications for the Space Ground Link Subsystem (SGLS). AFSCN TT&C. Flights 4-10 (Block II) also carry an Extremely High Frequency (EHF) package for secure, anti-jam communications, telemetry and commanding. Flights 8-10 (Block III) add a Global Broadcast Service (GBS) package for one-way, high data-rate communications in place of the SHF package. Projected orbital operational life of 14 years with an on-orbit storage life of four years.  UHF F/O Specifications Weight: 2,600 pounds Orbital Altitude: Geosynchronous orbit - 22,250 miles Power Plant: Two deployed three-panel solar array wings supplying approximately 2400 watts. A single 24-cell nickel- hydrogen (NiH2) battery provides power during eclipse operations (Block III satellites have two four-panel solar wings supplying approx W and a 32-cell battery). Dimensions: 9.5 feet high and 60.5 feet long launch Vehicle: Atlas-Centaur space booster Launch Site: Cape Canaveral Air Station, Fla. Primary Contractor: Boeing Space Systems, El Segundo CA

9 Voyager  The twin spacecraft Voyager 1 and Voyager 2 were launched by NASA in separate months in the summer of 1977 from Cape Canaveral, Florida. As originally designed, the Voyagers were to conduct closeup studies of Jupiter and Saturn, Saturn's rings, and the larger moons of the two planets.JupiterSaturn  To accomplish their two-planet mission, the spacecraft were built to last five years.  But as the mission went on, and with the successful achievement of all its objectives, the additional flybys of the two outermost giant planets, Uranus and Neptune, proved possible -- and irresistible to mission scientists and engineers at the Voyagers' home at the Jet Propulsion Laboratory in Pasadena, California.Uranus Neptune  As the spacecraft flew across the solar system, remote- control reprogramming was used to endow the Voyagers with greater capabilities than they possessed when they left the Earth. Their two-planet mission became four. Their five-year lifetimes stretched to 12+Earth  Between them, Voyager 1 and 2 would explore all the giant outer planets of our solar system, 48 of their moons, and the unique systems of rings and magnetic fields those planets possess.

10 Ground  Ground Activities: Spacecraft Flight Operations Payload Operations Payload Data Processing Payload Data Dissemination  Facilitated By: Real-Time Processing Payload Dissemination Infrastructure Powerful Payload Processing Facilities Mission Simulations Can Be Merged

11 Launch  Selection: Enough “throw weight” Enough “cube” (volume) Acceptable ride Good record…  Integration: Launch loads imparted to spacecraft Mechanical/Electrical Integration Understand launch “flow” and count

12 Space System Development 1.All systems development start with a “mission need” (the Why) 2.Then mission requirements are developed to meet this need (the What) often along with a concept of operations Note: Often we make the mistake of putting “the How” in the Mission Requirement 3.From 1 and 2 above develop derived requirements for (the How): Space  Mission orbit  Payload Types (Communications, remote sensing, data relay)  Spacecraft Design Ground  Facilities and locations  Computers/Software  Personnel/Training Launch segments  Note: The requirements generation process is often iterative and involves compromises  Remember, Mother Nature gets a vote and her vote counts

13 Spacecraft Development Process  Some types: Waterfall (sequential) Spiral (iterative)  Basic Sequence: 1.Conceptual design 2.Detailed design 3.Develop detailed engineering models 4.Start production 5.Field system 6.Maintain until decommissioned  DoD mandates integrated, iterative product development process Requirements Development Detailed Design Engineering Development & Production Field (IOC)

14 Textbook Answer:

15 Serial (waterfall) Development 1.Traditional “waterfall” development process follows logical sequence from requirements analysis to operations. 2.Is generally the only way to develop very large scale systems like weapons, aircraft and spacecraft. 3.Allows full application of systems engineering from component levels through system levels. 4.Suffers from several disadvantages: Obsolescence of technology (and sometimes need!) Lack of customer involvement/feedback Difficult to adjust design as program proceeds

16 Concurrent versus serial development The Concurrent development and manufacturing processes intended to optimize overall time to market and development productivity. 1.Incorporating customer needs/requirements into measurable and predictable targets; ensuring that the product meets or exceeds expectations. 2.Use simulation-led analysis and problem solving to design out problems and validate new designs before expensive prototypes and tooling are built. 3.Product testing ahead and concurrent with development programs to understand and quantify product performance before production is contemplated. Note: Also Allows full application of systems engineering to assure requirements are methodically managed from component levels through system levels.

17 Spiral Development From: And Barry Boehm, A Spiral Model of Software Development and Enhancement, IEEE Computer, 1988 Software Development Centric Example Good features 1.In this approach, the entire application is built working with the user. 2.Any gaps in requirements are identified as work progresses into more detail. 3.The process is continued until the code is finally accepted. 4.The spiral does convey very clearly the cyclic nature of the process and the project life span. Not so good features 1.This approach requires serious discipline on the part of the users. The user must provide meaningful realistic feedback. 2.The users are often not responsible for the schedule and budget so control can be difficult. 3.The model depicts four cycles. How many is enough to get the product right? 4.It may be cost prohibitive to “tweak” the product forever. Simply put: Build a little – Test a little! Can this work for every type of project?

18 Systems Engineering  A logical process for system development  Functional & physical decomposition of system into logical parts  Involves development of system requirements : System Analysis Requirements Development Interface Requirements  Requirements Validation Test & Demonstration Simulation Analysis  Physical/functional configuration audits  Integration & Test Planning  “Cradle to Grave” lifecycle planning Treaty provisions and DoD regulations require disposal of satellites at the end of life. Deep Space 1

19 Systems Engineering Verification The classic “V” for system development

20 Spacecraft Integration and Test CDR David Myre

21 Spacecraft Integration and Test  Methodical process for test of spacecraft to validate requirements at all levels  Sequence: 1.Perform component or unit level tests 2.Integrate components/units into subsystems 3.Perform subsystem tests 4.Integrate subsystems into spacecraft 5.Perform spacecraft level test 6.Integrate spacecraft into system 7.Perform system test when practical

22 System Integration and Test  Types: Functional testing  Do subsystems work together?  “Fit” check payload fairing, adapter Environmental testing  Thermal vacuum, shock and vibration testing Combined functional and environmental testing  Usually spacecraft level thermal vacuum involved integrated functional testing Final System demo: Do all segments work together, mainly ground and space  Payload or system characterization Performance can be altered by the space environment Often performed in thermal vacuum chamber  Can Use a combination of “hardware in loop” and simulation: Ground Testing Systems like propulsion and attitude control cannot be operated safely on the ground May use “stimulators” for sensors like sun & earth sensor, or star tracker. Got to the site below and play the movies if internet connection available: NOAA-N Prime, 6 Sep 03

23 Summary:  Functions: Mechanical (form and fit) Electrical/Electronic (power up to operational test)  Process: Starts at component level (e.g. transmitter, power supply…) Continues at subsystem level (e.g. electronic power system, attitude control system…) Ends with end-to-end test of entire system  Spacecraft Challenge: Effectively test spacecraft on the ground so it works in space!

24 Design Verification and Qualification Testing  Design Verification Validate design precepts and models Examine system limitations Build & Test, Build & Test…  Qualification: Determine system suitability for mission Provides tool for customer to measure success of the enterprise Allows time for fixes to meet requirements – may involve warranty period

25 DoD Test Process  Developmental Testing: Design Verification Qualification Acceptance Testing  Operational Testing: Operational Assessments (OA’s) Phased Operational Testing (OT) Mandated by law to protect YOU! From: COMOPTEVFOR’s Web Page In 1971, however, OPTEVFOR was designated the Navy's sole independent agency for operational test and evaluation. This move was in response to Congressional and Secretary of Defense initiatives aimed at improving the defense material acquisition process.

26 Types of Design/Qual Tests  Functional “Life” Testing (could involve structural, thermal, illumination, power cycling, radiation exposure etc.) Component to System Level Often performed in between other forms of test  Structural Static Tests Dynamic Tests  Thermal Thermal cycling Thermal vacuum Magellan

27 Launch Flow  Pack and Ship (Spacecraft & Launcher) Dry run spacecraft moves, lifts etc. Transportation loads can be driving cases for spacecraft structure  Establish launch operations Admin and work spaces for launch team  Test to insure no damage during shipping Perform limited subsystem and spacecraft tests  Establish communications with all players (launch base, groundstation) Perform rehearsals Multiple data and voice networks must be established Support spacecraft (TDRSS) must be in place

28 Review  Discussed the Segments of a space system: Ground, Space and Launch  Introduced major subsystems of typical spacecraft  Introduced the concept of systems engineering  Discussed Integration and Test of Spacecraft

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30 Another View: Eye Chart Anyone?

31 International Gamma-Ray Astrophysics Laboratory (Integral) INTEGRAL is an European Space Agency mission with instruments and science data centre funded by ESA member states (especially: Denmark, France, Germany, Italy, Spain, Switzerland), Czech Republic and Poland, and with the participation of Russia and the USA European Space Agency

32 Concurrent Development