Spacecraft engineering
AstroCraft Lab
Choose a bus, engines, tanks, power, antennas and instruments. The lab applies the rocket equation stage by stage, checks your power budget and tells you whether the design can fly the mission.
Design challenge
Engineering analysis
- Total mass
- 1,010.1 kg
- Dry mass
- 360.08 kg
- Propellant
- 600 kg
- Payload
- 50 kg
- Thrust (vac)
- 445 N
- Specific impulse
- 316 s
- Total Δv
- 2.793 km/s
- Thrust-to-weight
- 0.0449 (in g₀)
Power budget at 1.00 AU
Bar shows the share of generated power consumed.
Mass breakdown
- Bus: 180 kg
- Engines: 4.5 kg
- Tanks (dry): 50 kg
- Power: 35 kg
- Comms: 12 kg
- Instruments: 40 kg
- Structure & margin: 38.6 kg
- Payload: 50 kg
- Propellant: 600 kg
Estimated cost (illustrative)
US$57.0 million
Model assumptions
- Ideal rocket equation per stage (no gravity, drag or steering losses).
- Each engine draws from shared tanks; propellant mass = tank capacity × fill level.
- Structure, harness and margins add a fixed fraction of the spacecraft's other dry mass.
- Heat shield adds 12% and landing legs 8% of the mass they protect or land.
- Solar power = 1361 W/m² ÷ d² × area × 30% efficiency (beginning of life, Sun-pointed).
- Lift-off thrust-to-weight uses sea-level thrust and Earth's standard gravity; vacuum-only engines cannot lift off.
- Cost model (illustrative order of magnitude only): spacecraft build ≈ US$150,000 per kg of dry mass; booster stages ≈ US$20,000 per kg dry; launch ≈ US$3,000 per kg of mass delivered to orbit.
Classroom
Interactive experiments
Eight short experiments that build the physics behind spacecraft design, each with instructions, theory and learning outcomes.
Newton's laws
a = F/m = 4 m/s² · t = 0.00 s · v = 0 m/s · x = 0 m
Instructions
- Set a force and a mass.
- Press Run and watch the cart accelerate for 4 seconds.
- Double the mass and run again: what happens to the acceleration?
Theory
Newton's second law states F = m·a. A constant force on a constant mass gives constant acceleration, so velocity grows linearly (v = a·t) and distance quadratically (x = ½·a·t²). His third law explains rockets: the engine pushes exhaust backwards and the exhaust pushes the rocket forwards.
Learning outcomes
- Relate force, mass and acceleration
- Predict velocity and displacement under constant acceleration
How the lab calculates
Each stage's velocity change comes from the Tsiolkovsky rocket equation, Δv = Isp · g₀ · ln(m₀/m_f), where the mass of every later stage counts as payload for the earlier one. Thrust-to-weight at lift-off uses sea-level thrust, because vacuum-optimised engines cannot fire efficiently in the lower atmosphere. Solar output falls with the square of distance from the Sun.
Component figures are representative of real hardware classes and are rounded. The cost model is a deliberately simple order-of-magnitude estimate; real mission costs depend on far more than mass. Try the stand-alone rocket equation, thrust-to-weight and solar power calculators to explore each relation.