#deep space

Lagrange points are positions where a small body can orbit in sync with two larger masses. Why L1, L2, and L3 are unstable but useful, why L4 and L5 are stable and ancient, and what JWST's halo orbit at L2 costs to maintain.

How do spacecraft generate power? From silicon solar cells degraded by particle radiation to plutonium-fuelled RTGs running for decades — the engineering of spacecraft power systems and the constraints that determine which technology fits which mission.

Specific impulse (Isp) is the single most important performance metric in rocket propulsion. What it means physically, how it derives from exhaust velocity, why it governs mission architecture, and how every propulsion type compares — from cold gas to ion drives.

Nuclear thermal propulsion achieves twice the fuel efficiency of the best chemical rockets. How NERVA demonstrated the technology in 1968, why it was cancelled, and what DRACO and Centaur Z mean for the next generation of deep-space missions.

Space radiation is the most serious unsolved problem in human deep-space exploration. How the Van Allen belts work, what galactic cosmic rays do to biology and electronics, and why Mars transit radiation dose remains a hard constraint on mission architecture.

Ion drives and Hall thrusters accelerate xenon to 30–80 km/s and run for years. How electric propulsion works, why it cannot launch from Earth, and how Dawn, Hayabusa2, and BepiColombo redefined what small spacecraft can do.

How do spacecraft reach the outer planets without carrying impossible amounts of fuel? The physics of Hohmann transfers, gravity assists, and the Oberth effect — why orbital mechanics is the art of doing more with less.