Appunti di Space systems engineering and operations SSEO

BANALOGI

RHMs prop future will require a real regulation →

some Rics will disappear from the PL so its neutral

RATIX will change → We should back the cash flow

in a free sand that this situation is small, allows &

may be have MIPS for active of yours. Possibly we

should leave the version of later day one of the work

CMS

RHM there is many instrument (speed, payload) → this is

very common both for swifted and general mission

DESIGN PROCESS

All the 4 fields will have to work together → Concurrent legacy

All the subsystems are interconnected and will affect each other

So in current legacy we don’t work in sequence but the various

expert are working in // Another very important aspect to consider is the desired lifetime.

Mission requirements collected → pd & users, environment, electron, payload,

reliability, schedule, technology, budget

↳ how much ↔ to increase reliability,

we want to risk ↔ we use redundancy

in our mission ↔ and the backload → what increased cost will ↑

Staging requirements → products, staging level, flowing resources

RATIX there are some the user has always been in staging e

lockup solution (Δ) etc. in the project↑

So eliminative eg. if we can’tw/oa certain barrier

Other ex.g. - on a course I went for navigator jets blast or

its best plan to be stable, on ↑（ ≈ 2:30）

Sometimes we prefer tests just to understand if a possible

future mission (eg. human on Mars) is feasible

In space missions is very important to consider also the political and

economical issues.

TECH READINESS LEVELS (TRL)

Standard classification from 1 (less developed) to 9 (more developed)

of the development of a certain technology.

TRL 1 - just a basic idea

TRL 9 - system proven many times successfully in real mission.

Set to perform a flight (so we build and launch) for ESA we

must have reached at least technology of TRL 6.

Also for the software there is a TRL classification.

The level of the SW/HW is certified by the subject that certifies

your item.

PROCESS FLOW (I/O)

Different kind of missions will have to be managed in # ways.

For example if we consider 3 missions:

• -> S/C around Sun

• -> S/C around Earth

• -> S/C around Pluto

We'll have # aspects to be considered and # constraints to focus issue

• -> solar cell will decay path of S/C

• -> telemetry/ttk/p propagation (RSS, TICS, DDS )

RW: To change the orbit plane we can use propulsion or perform

a gravity assist (--> fly with a planet)

POWER BCS

• Power Budget
• Array Sizing
• EPS Definition
• Battery Selection and Sizing
• EPS Bus Control Definition

SAFE MODE -> when you're active, just to have energy and to transmit, this four independent activities.

PWR BCS doesn't allow to use nuclear power onboard in severe issues and pollution.

Run few of your solar cells or during active mode play with some battery for many reasons (e.g. to cover peaks)

CONFIGURATION

• Mass Budget
• CoG Position
• Equipments Allocation

STRUCTURES AND MECHANISM

• Structural Analysis
• Structural Mass Budget
• Mechanism Sizing / Selection

COSTS

• Cost Analysis
• Cost Budget

Costs are strongly related with many aspects that testing activity is present. If we choose a low level TRL, it will cost less but with level to need to test it.

RISKS

• Risk Analysis
• Mitigation Actions Definition

AVIONT

• Programma/Analysis
• Test Plan Definition

Usually - imports and verifications test.

Interfaces RBS

• Model
  • btw subsystems
  • with ext world (under, notify, grad state)
• Structural, power, voltage, figure, ... coherence

Trading-Off Alternatives

• High Level
  • Functionality
    • Requirements
• V & V
  • Criteria
    • Expert that allows us to make choice easy to implement

• Broad Alternatives
  • Sub to consider all the possibilities
  • Find a backup plan if the first choice has some pros
    • Robust (project risk)

Select the closure of phase B

Trading Off

• Perform in any phase
• Design using multicriteria decision making techniques

Design

• Flexibility > Optimality
• New designs to be reused
• Reusability
  • Redesign to use as much as possible existing modules

Turning S.O to buy?

• If possible better to buy
• Reviews in some layers :

Preliminary Design Review

• Critical Design Review
  • Pre-production design review
• After system model has been simulated & validated
• After first prototypes have been verified
• After preproduction system has been manufactured & tested

Environment

Sun

• Solar Constant
• Emissions
  • Blockbody with T_sun = 5800K
  • Place crucial in visible
  • Strong magnetic field
• 11 Years Solar Cycles
  • Related to sunspots and flares
  • IR number of sunspots
  • 5 F₁₀
  • Flux of 2.4-2.7m

HT in Space

• Radiation Sources
  • Sun
    • Flux depends on R_sun-sol
  • Albedo
    • Function of surface: UV
    • Display of planet
  • IR Radiation
    • Comes from T > 0K
  • Cold Space
    • Heat sink at 3K

Atmosphere

• Homosphere (0-90 km)
• Earth Atmosphere
  • Troposphere (0-12 km)
  • Stratosphere (12-50 km)
  • Mesosphere (50-90 km)
• Thermosphere (90; 250/170 km depending on solar activ.)
• Exosphere (until space)

SINGLE EVENT EFFECTS

Δin SAA change of state due to a single incoming particle

NON DISRUPTIVE

• SEU SINGLE EVENT UPSET

  • Change of state of operated element caused by particle square
  • Use immune material
  • Put protection stripes or bias to isolate susceptible element in SEU environment
  • Use error correcting algorithms

• SET SINGLE EVENT TRANSIENT

  • Transistory of analog-digital component
  • Use immune material

DISRUPTIVE

• SEL SINGLE EVENT LATCH UP

  • Transistory of analog-digital component
  • Use immune material
  • Insert FET-based elements in SAA
  • Avoid recoverable charged induced distortion component by parallel element
  • Use circuits to switch off system or induce parasitic currents