Spacecraft Systems
The subsystems that keep a spacecraft alive.
Course
Structure, power, thermal control, attitude control, computing, communications and payload, and how they share a limited budget of mass, power and volume.
Before you start
- School arithmetic
- Watts and grams as units
- Space Technology track recommended
Learning objectives
- Name the main subsystems of a small satellite and say what each one does
- Explain why every subsystem must work together for the mission to succeed
- Add up a simple mass budget and power budget and say whether a design fits
By the end you can
- Can point to each subsystem on a model and explain its job
- Can tell from a budget whether a design closes
Before you start
- Foundation level of this track, or equivalent
- Physics of electricity and heat
- Comfort with percentages and margins
Learning objectives
- Run a trade study between design options using mass, power and mission value
- Apply design margins and explain why they shrink as a design matures
- Estimate an equilibrium temperature with a radiative heat balance
- Relate attitude-control needs to payload pointing requirements
By the end you can
- Can lead a simple trade study
- Can explain why a design with zero margin is not finished
Lesson plan
Lessons · Ages 14–16
Anatomy of a CubeSat
- The 10 cm unit (1U)
- Frame and rails
- Stacked electronics boards
Power
- Solar cells
- Batteries for eclipse
- The power board
Brains and voice
- Flight computer
- Radio and antenna
- Ground stations
Pointing and payload
- Attitude control with magnetorquers
- Cameras and sensors as payloads
Budgets
- Mass budget
- Power budget
- Why designers keep a margin
Hands-on activities
- Build a 1U CubeSat in the 3D mission and explain each part to someone else
- Make a 10 cm cardboard cube and decide where each board, the battery and the camera would go
- Write the mass budget for your cardboard model with kitchen-scale measurements
Challenge: Build Your First CubeSat
Install the subsystems in a workable order, identify parts by their job, then balance the mass and power budgets.
Pass criteria
- All parts installed with internal parts before the side panels
- Three of three part-identification questions correct
- Mass within the lesson limit and power margin of zero or more
Physics and mathematics
Show the 3 equations
m_total = m₁ + m₂ + … + m_n
grams
Every part has a mass. The total must stay under the limit the launch allows.
P = V × I
P in W, V in volts, I in amps
Power is how fast energy is used. A 5 V board drawing 0.2 A uses 1 W.
E = P × t
E in Wh, P in W, t in h
A 2 W radio switched on for half an hour uses 1 Wh.
3D models
- 1U CubeSat with exploded and labelled views (available: Build Your First CubeSat)
- 6U Earth-observation satellite (existing: Satellite Explorer 3D)
Lessons · Ages 17–18
Systems engineering
- Requirements and verification
- Interfaces
- Trade studies
Budgets with margins
- Mass and power margins
- Orbit-average power
- Worst-case analysis
Thermal control
- Absorptivity and emissivity
- Radiative balance
- Heaters and radiators
Attitude determination and control
- Sensors: sun sensors, magnetometers, gyros
- Actuators: magnetorquers and reaction wheels
- Pointing accuracy
Hands-on activities
- Complete Build Your First CubeSat at the Advanced level, where the mass margin and the off-Sun check are stricter
- Compare body-mounted and deployable solar panels in a short written trade study
- Estimate the equilibrium temperature of a black and a white 10 cm cube in sunlight
Challenge: Close the Design
Choose payload, solar configuration and radio time so the CubeSat meets its data requirement with margins.
Pass criteria
- Mass margin of at least 10% against the lesson limit
- Power margin of at least 10% with the Sun 45° off the panel normal
- Trade-off explained in three sentences
Physics and mathematics
Show the 3 equations
margin = (allowed − estimate) ÷ estimate × 100%
percent
Early estimates are uncertain, so the margin protects the design from growth.
P = S × A × η × cos θ
S ≈ 1,361 W/m² near Earth, A in m², η as a fraction, θ = Sun angle
Generation falls with the cosine of the angle between the panel's normal and the Sun.
α × S × A_sun = ε × σ × A_rad × T⁴
σ = 5.67 × 10⁻⁸ W/(m²·K⁴), T in kelvin
In equilibrium the heat absorbed equals the heat radiated, which fixes the temperature.
3D models
- 1U CubeSat with budget overlays (available: Build Your First CubeSat)
- 6U satellite subsystems and flows (existing: Satellite Explorer 3D)
Classes and workshops
Online
Interactive 3D mission available now; live online classes planned.
In person
No offline workshop is planned for this track yet; its activities can be done at home or in a school lab.
Existing tutorials for this track
- Satellite Explorer 3DA 6U Earth-observation satellite in interactive 3D.
- Satellite EngineeringAdvanced programme: from first principles to systems architecture.
- Space StationOrbital stations: power, life support, docking, research.
- CubeTwinCubeSat energy digital twin: sunlight, battery, faults, safe mode.
Eligibility, independence and privacy
- Independent initiative. Space Academy is part of an independent ISHAVASYAM.ORG education initiative. It is not affiliated with, endorsed by, or run on behalf of ISRO, IN-SPACe, NSIL or the Department of Space.
- No competition eligibility. Learning here does not register anyone for, or make anyone eligible for, any national or international competition. Each competition's organisers set its rules and eligibility.
- Simulated and illustrative. Interactive missions use simplified models and simulated, illustrative values. They are labelled as such and are not flight data.
- Ages. Written for learners aged 14 to 18. Anyone may play the self-paced missions; enquiries from under-18s need a parent or guardian.
- Privacy. Missions never ask for a name, school, age or contact details. Progress is stored only in this browser and can be cleared at any time. This site uses Google Analytics to count page visits and mission steps. Some of the site's existing tutorials ask visitors to sign in with a Google account. If you are under 18, check with a parent or guardian before signing in.