Author: CislunarSpace
Source: CislunarSpace
Gateway Engineering Case Study
Lunar Gateway Overview
NASA's Lunar Gateway is the cornerstone infrastructure of the Artemis program — a small space station planned for operation in cislunar space. Unlike the International Space Station (ISS), the Gateway does not occupy a continuous resident orbit; instead, it operates in an L1 NRHO, periodically visiting the lunar surface and supporting deep-space missions.
NASA selected NRHO as the Gateway's operational orbit based on the following considerations:
- Orbital Stability: The quasi-periodic nature of NRHO in the CR3BP model reduces the propellant required for station-keeping
- Lunar Surface Accessibility: Transfer ΔV from NRHO to the lunar poles is approximately 200–400 m/s, superior to LEO
- Communication Coverage: NRHO provides good communication visibility to the lunar far side, especially the south pole
- Deep-Space Hub: NRHO can serve as an intermediate staging point for cis-lunar and deep-space missions
Gateway's target NRHO parameters: km, period approximately 6.5 days, located near the L1 point.
International Cooperation Framework
The Gateway is one of the largest multilateral space cooperation projects to date, with each partner developing and operating different modules:
| Partner | Module | Function |
|---|---|---|
| NASA (USA) | PPE (Power and Propulsion), HALO (Habitation and Logistics Outpost) | Power, propulsion, life support |
| ESA (Europe) | ESPRIT (European System Providing Refueling, Infrastructure and Telecommunications) | Propellant resupply, communications enhancement |
| JAXA (Japan) | I-HAB (International Habitation Module) | Crew habitation, scientific experiments |
| CSA (Canada) | Canadarm3 | Extravehicular robotics operations |
Each module is designed to operate independently or collaboratively in the Gateway NRHO, reflecting a modular, multinational design philosophy.
Cis-Lunar Transfer Design
Transfers from Earth to the Gateway NRHO are typically divided into two phases:
- Trans-Lunar Injection (TLI): Launch from LEO or direct injection into a trans-lunar trajectory
- NRHO Insertion: Orbital maneuvers near the L1 point to insert the spacecraft into the NRHO
A typical TLI energy budget is approximately km/s (relative to LEO), with NRHO insertion maneuvers after arriving at the L1 sphere of influence requiring approximately 200–400 m/s.
Alternative Orbit Comparison
During the Gateway planning phase, DRO was also considered as an alternative operational orbit. In comparison:
| Characteristic | NRHO | DRO |
|---|---|---|
| Lunar Surface Accessibility | Good (200–400 m/s to poles) | Poor |
| Station-Keeping ΔV | 30–80 m/s/year | 5–20 m/s/year |
| Earth Communication | Good | Better |
| Lunar Far-Side Coverage | Moderate | Poor |
| Engineering Maturity | Low (Gateway is first large-scale application) | Higher (validated by CAPSTONE) |
NASA ultimately selected NRHO as the Gateway's operational orbit primarily due to its accessibility advantage to the lunar surface, especially the south pole landing zone.
Simulation Experiment
In the Satellite Orbit Simulation Lab, you can set typical Gateway NRHO parameters to observe the orbital profile and design transfer trajectories to the lunar surface.