engineering

System requirements (spacecraft system)

System requirements (spacecraft system) is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand System requirements (spacecraft system) rather than just read about it. In short: System requirements in spacecraft systems are the specific system requirements needed to design and operate a spacecraft or a spacecraft subsystem. Overview Spacecraft systems are normally developed under the responsibility of space agencies as NASA, ESA etc.

Key takeaways

System requirements (spacecraft system) belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect System requirements (spacecraft system) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of System requirements (spacecraft system) from memory before moving on to harder problems.

Reference excerpt

System requirements in spacecraft systems are the specific system requirements needed to design and operate a spacecraft or a spacecraft subsystem.

Overview

Spacecraft systems are normally developed under the responsibility of space agencies as NASA, ESA etc. In the space area standardized terms and processes have been introduced to allow for unambiguous communication between all partners and efficient usage of all documents. For instance the life cycle of space systems is divided in phases:

Phase A: Feasibility Study Phase B: Requirements Definition Phase C/D: Design / Manufacturing / Verification Phase E: Operational usage. At the end of phase B the system requirements together with a statement of work are sent out requesting proposals from industry.

Technical systems requirement

Both technical and nontechnical system requirements are contained in the statement of work. The technical system requirements documented in the System Specification stay on mission level: System functions and performances, Orbit, Launch vehicle, etc. Non-technical system (task) requirements: Cost and progress reporting, Documentation maintenance, etc. The customer (requirements) specification is answered by the contractor by a design-to specification. For example, the requirement "Columbus shall be launched by the Space Shuttle." is detailed in the contractor system specification "Columbus shall be a cylindrical pressurized module with max. length of 6.9 meters and 4.5 meters diameter as agreed in the Shuttle/Columbus ICD."

Operations environment The spacecraft's systems specification, according to David Michael Harland (2005), usually also defines the operation environment of the spacecraft. It mostly is defined "as a model - often provide by the scientific community from available data - in the form of a set of curves, numerical tables, or software, usually with a nominal expectation and the minimal and maximum profiles which the environment is not expected to exceed".

System specification structure A typical industry generated system specification for a spacecraft has the following structure (e.g. Columbus Design Spec (COL-RIBRE-SPE-0028, iss.10/F, 06.25.2004):

Document change record 1. Scope 1.1 Purpose 1.2 Summary description 1.3 Classification 1.4 Applicability 2. Related documents 2.1 Applicable documents (incl. order of precedence) 2.2 Reference documents 3. Functional /Performance Requirements 4. Support requirements 4.1 Product assurance 4.2 Electro-magnetic compatibility 4.3 Contamination 4.4 etc. 5. Interface requirements 5.1 System interfaces 5.1.1 Launcher 5.1.2 Ground stations 5.1.3 etc. 5.2 Subsystem interfaces 5.2.1 Electrical power 5.2.2 Data 5.2.3 etc. 6. Implementation requirements 6.1 Configuration 6.2 Budget Allocations 6.2.1 Mass 6.2.2 Electrical power 6.2.3 etc. 7. Preparation for delivery Attachments (Abbreviation list etc.) Each requirement paragraph consists of the requirement to be fulfilled by the product to be delivered and the verification requirement (Review of design, analysis, test, inspection).

Specification tree The spacecraft system specification defines also the subsystems of the spacecraft e.g.: Structure, Data management subsystem incl. software, Electrical Power, Mechanical, etc. For each subsystem a subsystem specification is prepared by the Prime Contractor with the same specification structure shown above including references to the parent paragraph in the system specification. In the same way the subsystem contractor prepares an assembly or unit specification. All these specifications are listed in a so-called specification tree showing all specifications and their linkage as well as the issue / date of each specification.

Literature 2005, David Michael Harland, Ralph Lorenz, Space Systems Failures: Disasters and Rescues of Satellites, Rockets, Springer, p. 178. 2003, Peter W. Fortescue, Graham Swinerd, Spacecraft Systems Engineering, John Wiley and Sons, 704 pp. 2001, DoD - Systems Management College, Systems Engineering Fundamentals. Defense Acquisition University Press, January 2001.

See also Requirements Requirements analysis Requirements engineering Requirements management Verification of system requirements Verification (spaceflight)

References

External links NASA Completes Milestone Review Of Next Human Spacecraft System Nasa article 1999. Example of a SYSTEM REQUIREMENTS sheet for a spacecraft [1] Columbus System Specification COL-RIBRE-SPE-0028 for phase C/D

Illustrations

System requirements (spacecraft system): Systems requirements can be specified in a "Requirements Allocation Sheet".[2] — Systems requirements can be specified in a "Requirements Allocation Sheet".[2]

Worked examples

Example 1 — a first encounter with System requirements (spacecraft system)

Start with the simplest possible case. Write down what System requirements (spacecraft system) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to System requirements (spacecraft system) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about System requirements (spacecraft system) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of System requirements (spacecraft system)

In research: System requirements (spacecraft system) appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses System requirements (spacecraft system) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: System requirements (spacecraft system) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Spaceflight concepts, Systems engineering, so understanding it makes those chapters shorter.
In everyday life: Look for System requirements (spacecraft system) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study System requirements (spacecraft system) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what System requirements (spacecraft system) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain System requirements (spacecraft system) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is System requirements (spacecraft system) in simple terms?

System requirements in spacecraft systems are the specific system requirements needed to design and operate a spacecraft or a spacecraft subsystem. Overview Spacecraft systems are normally developed under the responsibility of space agencies as NASA, ESA etc.

Why does System requirements (spacecraft system) matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study System requirements (spacecraft system)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on System requirements (spacecraft system).