1 Space Systems Overview CDR David D. Myre. 2 What is a Space System? Ground Spaceflight Operations Payload Operations (Can be separate) Payload Data.

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Space Systems Overview

CDR David D. Myre

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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

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Tracking and Data Relay Satellite System

http://nmsp.gsfc.nasa.gov/tdrss/oview.html

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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

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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

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TDRSS 1-7 Specifications

Dimensions: 45 feet wide / 57 feet longWeight: 5000 poundsDesign Lifetime: 10 yearsPower (EOL): 1800 wattsServices: KU & S-Band servicesLaunch Vehicle: Space ShuttleOrbit: Geosynchronous

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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

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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. 3800 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

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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.

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.

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+

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.

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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 BeMerged

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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

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Space System Development1. 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 operationsNote: 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

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Spacecraft Development Process Some types:

Waterfall (sequential) Spiral (iterative)

Basic Sequence:1. Conceptual design2. Detailed design3. Develop detailed

engineering models4. Start production5. Field system6. Maintain until

decommissioned DoD mandates integrated,

iterative product development process

RequirementsDevelopment

DetailedDesign

EngineeringDevelopment

&Production

Field(IOC)

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Textbook Answer:

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Serial (waterfall) Development1. 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

http://www.csse.monash.edu.au/~jonmc/CSE2305/Topics/07.13.SWEng1/html/text.html

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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.

http://www.iti-oh.com/TechKnowledgy/ParadigmShift.htm

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Spiral Development

From: http://www.maxwideman.com/papers/linearity/spiral.htmAnd Barry Boehm, A Spiral Model of Software Development and Enhancement, IEEE Computer, 1988

Software Development Centric Example

Good features1. 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 features1. 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?

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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

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Systems Engineering Verification

The classic “V” for system development

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Spacecraft Integration and Test

CDR David Myre

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Spacecraft Integration and Test Methodical process for test of

spacecraft to validate requirements at all levels

Sequence:1. Perform component or unit

level tests2. Integrate components/units into

subsystems3. Perform subsystem tests4. Integrate subsystems into

spacecraft5. Perform spacecraft level test6. Integrate spacecraft into

system7. Perform system test when

practical

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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:http://www.boeing.com/defense-space/space/bss/hsc_pressreleases/photogallery/uhf_f11/uhf11_video/uhf11_movies.html

NOAA-N Prime, 6 Sep 03

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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!

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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

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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 http://www.cotf.navy.mil/

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.

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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

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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

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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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Another View: Eye Chart Anyone?

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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

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Concurrent Development