How nodes are rated
A Node Is Rated by Whether Anything Has Stopped There
A node is anywhere a vehicle stops, refuels or hands off cargo: an orbit, a libration point or a surface.
Observed means a spacecraft has landed, entered orbit or held station at the node; for the Mars transfer state, that missions have departed through it.
Building means a mission in development will stop there. Projected means an agency has announced one. Modeled means the node exists only in original analysis.
Flybys do not count. Callisto, Triton and Pluto have all been imaged up close; nothing has stopped at any of them.
The nodes
The Node Index
16 nodes; each links to its destination or corridor page. Corridors counts the edges in the Corridor Index that touch the node.
| Node | Type | Gravity | Light time, one way | Corridors | First stop | Rated |
|---|---|---|---|---|---|---|
| LEO | Orbit, 200-2,000 km | - | Under 0.01 s | 11 | Vostok 1, 1961; Tiangong since 2021 | Observed |
| GEO | Orbit, 35,786 km | - | 0.12 s | 1 | Syncom 3, 1964 | Observed |
| SEL-1 | Libration point, 1.5 million km sunward | - | 5 s | 1 | ISEE-3, 1978; Aditya-L1, 2024 | Observed |
| SEL-2 | Libration point, 1.5 million km anti-sunward | - | 5 s | 1 | WMAP, 2001; Chang'e-2, 2011; JWST since 2022 | Observed |
| EML-1 | Libration point | - | 1.1 s | 3 | ARTEMIS P2, 2010 | Observed |
| Lunar orbit | Orbit, about 100 km | - | 1.3 s | 1 | Luna 10, 1966; Queqiao-2 since 2024 | Observed |
| Lunar surface | Surface | 1.62 m/s2 | 1.3 s | 3 | Luna 9, 1966; Chandrayaan-3 near the south pole, 2023 | Observed |
| Mars transfer | Departure state | - | Varies | 1 | Mariner 4, 1964 | Observed |
| Mars surface | Surface | 3.71 m/s2 | 3-22 min | 2 | Viking 1, 1976; Zhurong, 2021 | Observed |
| Phobos | Moon surface | 0.006 m/s2 | 3-22 min | 1 | None yet; JAXA MMX sample return in development | Building |
| Deimos | Moon surface | 0.003 m/s2 | 3-22 min | 1 | None; flyby imaging by Viking and the UAE Hope orbiter | Modeled |
| Ceres | Surface | 0.28 m/s2 | 15-31 min | 2 | Dawn, in orbit 2015-2018 | Observed |
| Callisto | Moon surface | 1.24 m/s2 | 33-53 min | 1 | None; Galileo flybys; CNSA Tianwen-4 announced | Projected |
| Titan | Moon surface | 1.35 m/s2 | 67-92 min | 1 | Huygens landed 2005; NASA Dragonfly launches 2028 | Observed |
| Triton | Moon surface | 0.78 m/s2 | About 4 h | 1 | None; Voyager 2 flyby, 1989 | Modeled |
| Pluto-Charon | Surface | 0.62 m/s2 | 4-7 h | 1 | None; New Horizons flyby, 2015 | Modeled |
Gravity wells
Escape Speed Decides Which Nodes Can Export
Escape speed from the surface and the atmosphere a vehicle can use on arrival.
| Node | Escape speed | Atmosphere | What it means | Rated |
|---|---|---|---|---|
| Lunar surface | 2.38 km/s | None | Every landing is powered; a mass driver can reach orbit | Observed |
| Mars surface | 5.03 km/s | About 0.6% of Earth's pressure | Aerobraking does most of arrival; departure is the hard leg | Observed |
| Phobos | 11 m/s | None | Docking, not landing | Observed |
| Deimos | 6 m/s | None | Docking, not landing | Observed |
| Ceres | 0.51 km/s | None | Low enough for an elevator - see The Asteroid Belt | Observed |
| Callisto | 2.44 km/s | Trace | Outside Jupiter's main radiation belts | Observed |
| Titan | 2.64 km/s | 1.5 bar, nitrogen | Aerocapture and parachutes; Huygens took about two and a half hours to descend | Observed |
| Triton | 1.45 km/s | Trace nitrogen | Aerocapture uses Neptune's atmosphere, not Triton's | Observed |
| Pluto | 1.21 km/s | Trace nitrogen | Powered landing | Observed |
Phobos and Deimos sit at the bottom of the Mars list but the top of its value: material leaves them for meters per second. See Mars.
China
Chinese Hardware at the Nodes
Station, relays, landers, a rover and an announced Callisto orbiter.
| Node | Program | Data point | Rated |
|---|---|---|---|
| LEO | Tiangong · CMSA | Crewed since 2021; Hall thrusters for orbit keeping | Observed |
| GEO | Shijian-21 · CAST | Towed a dead BeiDou satellite to a graveyard orbit, 2022 | Observed |
| SEL-1 | Chang'e-5 orbiter · CNSA | Extended mission after the lunar sample return, 2021 | Observed |
| SEL-2 | Chang'e-2 · CNSA | First Chinese libration-point stay, 2011 | Observed |
| EML-2, not indexed | Queqiao-1 · CNSA | Far-side relay for Chang'e-4 since 2018 | Observed |
| Lunar orbit | Queqiao-2 · CNSA | Frozen elliptical relay orbit since 2024 | Observed |
| Lunar surface | Chang'e-4 and Yutu-2 · CNSA | Far side, Von Kármán crater, since 2019 | Observed |
| Lunar surface | ILRS · CNSA and Roscosmos | South-pole base; nuclear power station delivery 2035 | Projected |
| Mars surface | Tianwen-1 and Zhurong · CNSA | Landed in Utopia Planitia, May 2021 | Observed |
| Callisto | Tianwen-4 · CNSA | Jupiter system mission ending in Callisto orbit | Projected |
Contested
Deliberately Not Claimed
The load-bearing uncertainties, tagged with the confidence they actually earn.
The index carries EML-1 only. Queqiao-1 used EML-2, and NASA's Gateway is planned for a near-rectilinear halo orbit (NRHO). Both are real staging points that a later revision may add as nodes.
The lunar surface is one node. A south-pole site at Shackleton and an equatorial mare site differ in lighting, ice and thermal environment; the corridor Δv to each is nearly the same.
Record
Provenance and Data Sources
- Confidence
- Observed for flown, fielded or measured - Building for hardware and programs in development - Projected for announced plans - Modeled for original analysis. Nodes are rated by whether anything has stopped there
- Status date
- Q4 2026
- Physical data
- Surface gravity and escape speed from published planetary constants; light time at minimum and maximum Earth distance
- China
- CMSA Tiangong; CNSA Chang'e, Queqiao and Tianwen; CAST Shijian-21; ILRS
- Weakest link
- Which libration points and halo orbits deserve node status