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Space Engineering: A World of Difference Ir. A. Kamp a.kamp@lr.tudelft.nl http://as.lr.tudelft.nl Delft University of Technology Astrodynamics & Satellite Systems Space = Remoteness from Earth Our familiarity with Protective Earth atmosphere 1-G environment

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Space = Remoteness from Earth

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Space Engineering: A World of DifferenceIr. A. Kampa.kamp@lr.tudelft.nlhttp://as.lr.tudelft.nlDelft University of TechnologyAstrodynamics & Satellite Systems


Space = Remoteness from Earth

  • Our familiarity with

    • Protective Earth atmosphere

    • 1-G environment

    • Accessibility for repair/inspection

  • Is partly lost in Space Engineering


What Makes It So Different?

  • Space: different and “strange” environment

  • Demanding performance requirements

  • Complex systems

  • Multidisciplinary

  • Severe safety

  • High availability

  • Many interfacing parties


Top ClassComplexity, Safety, Availability, Interfaces


Complex and High Cost Systems

  • Cost per kg

    • INTELSAT: development & launch 250,000 €/kg in-orbit mass

    • ISS: 450,000 €/kg

    • Globalstar: 50,000 €/kg

    • Mid-sized car: 25 €/kg

  • Number of personnel involved in development

    • >100-200

  • Time required from initial conception till operation

    • 3-10 years

Ref: AE1-801 SE&T I


Objective of Presentation

  • How “strange” is the Space Environment?

  • Some of the impact on engineering

  • How are space systems developed?to minimise

    • development risk and risk of failure


What Is Space?

  • It is difficult to get to and to stay in

  • Acompletely unforgivingenvironment

    • If you screw up the engineering, SOMEBODY DIES!

  • A very hostile environment

  • It’sdifferent!


Space: Difficult To Get In

  • Severe launch loads

Antenna

Acoustic loads

box

Random loads

LVA

Steady State SinusShock loads


Dimensioning Instruments, Electronic Boxes, Etc

Size your equipment to withstand the static load factors and the severe random vibrations

60

5


Mechanical Engineering

  • In-depth analysis

    • Stress

    • Dynamic and Acoustic

    • Thermal distortion

    • Fatigue

    • Micro-vibration

    • Mass budgeting

  • Structural testing(random vibrations, acoustic, shocks)


Space Environment

  • Kind

    • No water vapour

    • No wind

    • Very clean environment

    • Zero effective gravity

  • Hostile

    • Hot and cold

    • Very high vacuum

    • Atomic oxygen

    • High energy electromagnetic radiation

    • Particle radiation

    • Debris


Hot and Cold

  • Solar flux density:on earth 500 W/m2in space 1400 W/m2

  • Earth surface 293 K cold space 4 K

  • No convection


Hot and Cold

  • Without special measures material temperatures in earth orbitmay vary between –270 and +130 C


Good Performance Only If

  • Narrow temperature ranges

    • Electronics typically –10/ + 40 C

    • Batteries- 5/ + 15

    • Hydrazine fuel+ 9/ + 40

  • Limited thermal gradients

  • Adequate thermal stability


ENVISAT Thermal Protection

Thermal blankets

Superior insulation

Radiators

Rejection of heat


Thermal Engineering

  • Design analysis

  • Thermal testing in vacuum/solar sim.

    • Verify the predicted temperature extremes

    • Verify proper functioning of equipment under TV conditions

      • After thermal cycling

      • At Textreme


High Vacuum

  • Immediately life threatening

  • Engines have to carry fuel and oxidizer

  • Risk of “cold welding”

  • Risk of inadvertent pressure vessels


Still: Atmospheric Drag


Atmospheric Drag Cleans Up


High Vacuum: Contaminating?

  • Sublimation of materials (outgassing)

  • Contaminants deposit on sensitive surfaces

  • UV radiation leads to polymerisation of organic molecules


Cleanliness Engineering

  • Material selection

    • No Cadmium, Zinc, Magnesium, plastics

    • Only special adhesives, and lubricants for mechanisms

  • Outbaking of volatile materials, all equipment

    • Typ. 3 days @ 80 C in vacuum

  • Contamination Budget Analysis

  • Contamination monitoring and control during AIT


Thinking Clean, Working Clean

SCIAMACHY optical instrument integration in Clean Room 100 conditions


Effective Absence of Gravity

  • An advantage or a disadvantage?

    • What happens to an astronaut when he swings a hammer and hits the nail?

    • Where is my liquid propellant in the tank?

  • Structures designed for weightlessness may not be testable on ground:design for testability!


Solar Array Deployment Test

Test Engineering


Solar and Cosmic Radiation

  • Flying through a plasma of charged particles (protons, electrons, heavier ionized atoms)

  • Typ. 450 km/s

  • How to shield or harden your electronics design?

  • What about static charging?


OMI Instrument Proton Shielding

  • Concept withoutand with shielding

Ref: Dutch Space OMI PSR Sep 2002


Diversity of Requirements


Managing Risk of Failures

  • Ensure project’s conservative approach

  • Track weaknesses found in the design analysis, manufacturing, test and operationsRAMS Engineering

  • Standardisation of design and development

    • ECSS: European Cooperation for Space StandardizationECSS-E-20A Electrical and Electronic

    • www.ecss.nl


Need for Systematic Approach

  • High complexity, high development risk

  • Little time to iterate

  • No chance to inspect or repair in orbit

  • Aiming for near-absolute reliability!

    Systems Engineering:

    First things first

    First time right!


High Speed Line Tunnel Drilling

Complex systems, Multidisciplinary, Safety,

Many interfacing parties


Systems Engineering Method

  • Structured development process

  • User requirements driven

  • Timely integration of all disciplines

  • Well motivated choices between all options

  • Visibility/traceability

  • Control

  • With the end product always in mind


Space System Development Flow

Requirements discovery

Development philophy

Cost break-down

Resource budgeting

Risk map

Systems Engineering flow in time:

Requirements flow-down and traceability

Design options trade-offs

Verification planning


Space System Development Flow

In depth:


Spacecraft

Payload

S/C Bus

Communication

Propulsion

Meteorology

ElectricalPower

Remote Sensing

ThermalControl

Propulsion

Structure

……….

Telemetry&Commands

Spacecraft Subsystems

Guidance, Navigation & Control

Computer & Data Handling


Web Links Used

  • http://www.esa.int and http://envisat.esa.int

    (sheets 8,10,13,15,16,17)

  • www.delftaerospace.com (sheets 8,9,26)

  • http://seds.lpl.arizona.edu/nineplanets (sheet 12)

  • http://www.ee.surrey.ac.uk (sheet 14)

  • http://science.nasa.gov/ (sheets 20,21)

  • www.dutchspace.nl (sheet 22,24)

  • http://www-istp.gsfc.nasa.gov/Education (sheet 27)

  • www.ecss.nl (sheet 29)

  • www.highspeed.nl (sheet 31)

  • www.loesje.org (sheet 37)


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