Launch energy
Compare direct translunar injection, Earth-orbit phasing, low-energy transfer, and rideshare constraints.
Past lunar mission
Lunokhod 2 / Luna 21
Lunokhod 2 / Luna 21 is a past Moon mission entry covering launch, transfer, lunar operations, and engineering context.
Animated launch, translunar trajectory, lunar operations, and return or descent path.
Mission facts
Launch and expedition data
- Status
- Past
- Agency
- Soviet Union
- Launch
- 1973
- Vehicle
- Proton-K
- Destination
- Le Monnier crater
- Mission class
- Robotic rover
Trajectory and outcome
Flight sequence
- Trajectory
- Lunar orbit, descent, and rover deployment
- Expedition
- Long-distance rover traverse with imaging and geophysical measurements
- Outcome
- Extended robotic surface mobility experience
Detailed notes
What this mission teaches
- Mission class: Robotic rover.
- Transfer profile: Lunar orbit, descent, and rover deployment.
- Lunar work: Long-distance rover traverse with imaging and geophysical measurements.
- Result or planning state: Extended robotic surface mobility experience.
Technical Review
What to compare against other lunar missions
Navigation
Flybys and orbiters stress tracking and burn accuracy; landers add powered descent, hazard detection, and autonomous terminal guidance.
Surface operations
Rovers, landers, and crewed missions have very different thermal, dust, communications, and power constraints.
Return path
Sample-return and crewed missions add ascent, rendezvous, entry interface, heat shield, and recovery risk.
Mathematical model
Mission trajectory and spacecraft model
Mission visuals combine catalog dates, distance vectors, speed estimates, and schematic spacecraft geometry. They are not CAD-certified vehicle meshes unless a source model is explicitly loaded.
Vector propagation
\[\mathbf{r}(t)=\mathbf{r}_0+\mathbf{v}(t-t_0)\]
For live-distance spacecraft pages, current position is propagated from epoch vector and velocity when high-precision ephemerides are not bundled.
Transfer curve
\[\mathbf{r}_{\mathrm{curve}}(u)=\operatorname{Bezier}\!\left(\mathbf{r}_{\mathrm{launch}},\mathbf{r}_{\mathrm{mid}},\mathbf{r}_{\mathrm{target}}\right)\]
Mission path arcs are schematic transfer curves anchored at meaningful endpoints, not claims of exact reconstructed trajectories.
Dimensional hierarchy
\[T_{\mathrm{world}}=T_{\mathrm{parent}}RS\]
Spacecraft parts are placed with transformation matrices. This proves the generated geometry is internally consistent even when simplified.
Verification standard: the rendered object must be reproducible from stated equations, catalog parameters, or explicit geometric transforms. Visual reference images may inform presentation only; they are not the source of orbital positions, field vectors, accretion-disk gradients, timing, or engineering layout.
Limitations: browser scenes may use bounded scale, compressed distances, simplified two-body dynamics, schematic transfer curves, or educational approximations where full numerical ephemerides, CFD, finite-element models, or general-relativistic ray tracing are outside the page scope. Those simplifications are part of the model contract, not hidden image-based construction.