Aerospace · Projected milestone
A sail carries science to Neptune in two years
20% by 2080 · including earlier years
The year is an editorial timing estimate. The percentage applies to occurrence by the stated deadline. These estimates are not calibrated odds.
A spacecraft with at least one kilogram of functioning scientific payload crosses Neptune’s mean orbital distance within 24 months after departing Earth, obtains and transmits a calibrated outer-solar-system measurement, and derives most of its post-departure velocity increase from photon pressure on a sail.
Explore this milestone on the interactive mapWhat the forecast means
Milestone stage: deep space flight demonstration
2010 component foundation: Solar sailing has flown; a kilogram-scale scientific sprint to Neptune’s distance has not.
The cited year dates a component or precursor result. The full event defined above has not been demonstrated.
Timing window: 2038–2080. An editorial range, not a statistical confidence interval.
Completion criteria: A spacecraft with at least one kilogram of functioning scientific payload crosses Neptune’s mean orbital distance within 24 months after departing Earth, obtains and transmits a calibrated outer-solar-system measurement, and derives most of its post-departure velocity increase from photon pressure on a sail. Resolve only after inspectable dated observations and independent assessment meet every stated criterion; a simulation, announcement or prototype lacking these thresholds does not resolve the event.
This page describes a forecast, rather than an achieved result. Read the methodology and assumptions.
Built on
Led to
Sources & evidence
- Extreme Metamaterial Solar Sails for Breakthrough Space Exploration 2020-04-07
A NIAC study proposes heat-tolerant ultrathin sails for close solar passages and high outward speeds. Its extreme trajectories remain concept estimates, not demonstrated payload delivery.
- ScienceCraft for Outer Planet Exploration (SCOPE) 2024-05-01
The concept integrates a lightweight spectrometer into a sail architecture for outer-planet exploration. It does not establish the mass, speed or endurance of Astra’s proposed courier.
Astra editorial synthesis; cited researchers retain credit for their work
Record reviewed 2026-10-18