Transfer Window

Transfer Window

Plan burns and a departure date that carry a craft from Earth to another world on the delta-v you have.

Earth, a target world, and a delta-v budget. Scrub the calendar to choose when to leave, plan prograde or retrograde burns, then press fly — the one commitment. The craft follows the conic your burns made while the target keeps moving, and you scrub through what happened: the meeting, the orbit reached where the planet had been, the flyby that did what your tank could not.

• 1Out to Mars's OrbitMore at once
• 2Meet MarsMore at once
• 3Mars on a BudgetTighter budgetUses the phase timing Meet Mars taught: the budget leaves room only for the cheapest transfer flown on the right day.
• 4Inward to VenusLess helpTighter budget
• 5Saturn by Way of JupiterTighter budgetOpenUses the window reading of the Mars levels, now for Jupiter, and adds the flyby: the budget is priced so that Saturn direct does not fit.

The tag on each level says how it gets harder. Levels gate on ideas, not on each other — jump wherever it gets interesting.