**Summary**
The current Artemis plan relies on NASA’s SLS to send the Orion capsule to the Moon, but Orion’s limited propulsion (≈1,300 m/s ΔV) cannot perform the trans‑lunar injection (≈3,100 m/s ΔV) on its own. To compensate, the mission must use a distant Near‑Rectilinear Halo Orbit (NRH), which adds ~1.5 km/s of extra ΔV for landing/ascent, forces Starship’s human‑landing system (HLS) to carry ~45 t of extra propellant, and ultimately requires 4–5 additional Starship tanker launches per mission (≈400–450 t of fuel). This architecture also suffers from propellant boil‑off, tight launch windows, high complexity, and cramped crew quarters in Orion.
A proposed “Orion on the nose” redesign flips the roles:
1. **SLS launches Orion (with crew) only to low Earth orbit (LEO).**
2. **Starship HLS launches separately, is fully refueled by tankers in LEO, and docks nose‑to‑nose with Orion in LEO.**
3. **Starship provides the full trans‑lunar injection and lunar‑orbit insertion burns for the combined stack.**
4. **The crew transfers to Starship for the lunar descent, surface operations, and ascent back to low lunar orbit, where they re‑dock with Orion for the trans‑Earth injection burn.**
5. **Orion then returns the crew to Earth using its own propulsion.**
**Key advantages**
- **Fuel savings:** ~450 t less propellant per mission (≈5 fewer tanker launches).
- **ΔV reduction:** Low‑lunar‑orbit operations need ~4 km/s each way vs. ~5.5 km/s from NRH; total round‑trip ΔV drops from ~9.6 km/s to ~9.0 km/s.
- **Less boil‑off & idle propellant:** Shorter trajectory means cryogenic fuel spends less time in tanks.
- **Greater launch flexibility:** Orion only needs to reach LEO; Starship can wait, widening launch windows and easing aborts.
- **Improved safety & redundancy:** Two docked spacecraft provide backup life‑support/power.
- **Crew comfort:** Starship offers ~600 m³ habitable volume (vs. Orion’s cramped capsule), reducing stress on multi‑day transit.
- **Programmatic impact:** SLS’s role shrinks to an LEO delivery vehicle (a setback for Boeing), while SpaceX’s reusable refuelable architecture gains validation and could accommodate other crew vehicles (e.g., Crew Dragon, crew‑rated Starship).
Overall, the “Orion on the nose” concept promises a cheaper, simpler, safer, and more comfortable lunar mission by leveraging Starship’s large propellant capacity and reusability, while relegating SLS to a limited LEO transport role.
1. Starship human landing system could save 450 tons of fuel by abandoning NASA’s current Artemis plan and adopting a more efficient architecture.
2. 450 tons of saved fuel equals the propellant for about five extra Starship tanker launches.
3. The original Artemis architecture’s main bottleneck is Orion’s limited propulsion capability.
4. SLS Block One is responsible for sending Orion toward the moon via a trans‑lunar‑injection burn.
5. SLS is a fully expendable rocket costing roughly $1 billion per launch with a low production cadence.
6. Orion provides only about 1,300 m/s of delta‑v, while a full trans‑lunar‑injection requires ≈ 3,100 m/s.
7. Because of this deficit, Orion cannot reach the moon or return from low lunar orbit on its own.
8. NASA therefore based Artemis on a distant near‑rectilinear halo orbit (NRH) to accommodate Orion’s limits.
9. Operating from NRH instead of low lunar orbit adds roughly 1.5 km/s of extra delta‑v for the round‑trip descent and climb.
10. To offset the NRH penalty, Starship HLS must carry about 45 additional tons of propellant for lunar surface operations.
11. Placing those 45 tons of usable fuel on the moon requires loading roughly 400–450 extra tons of propellant in low Earth orbit beforehand.
12. Consequently, Artemis could need four to five extra Starship tanker launches per mission just to support fuel that would later be burned due to NRH inefficiency.
13. The original plan also relied on the lunar Gateway as an NRH rendezvous hub for Orion and Starship docking before landing.
14. In the redesigned “Orion on the nose” architecture, SLS launches Orion and crew into low Earth orbit (LEO).
15. Separately, a Starship HLS launches into orbit and is fully refueled via tanker flights.
16. Rendezvous occurs in LEO, with Orion docking to the nose of Starship.
17. Starship then performs the full trans‑lunar‑injection burn, pushing the combined stack toward the moon.
18. After reaching the moon, Starship conducts lunar‑orbit insertion for the combined spacecraft.
19. The crew transfers to Starship, descends to the lunar surface, conducts surface operations, then launches back to rendezvous with Orion in low lunar orbit.
20. Orion separates and uses its own propulsion for the trans‑Earth‑injection burn to return the astronauts.
21. Missions from low lunar orbit require about 4.0 km/s each way for descent and ascent, versus ≈ 5.5 km/s each way from NRH.
22. Total round‑trip delta‑v drops from roughly 9.6 km/s (NRH‑based) to about 9.0 km/s when operating from low lunar orbit—a reduction of ≈ 0.6 km/s.
23. The shorter LEO‑to‑LLO trajectory reduces propellant boil‑off because cryogenic fuel spends less time in tanks.
24. The new approach involves fewer orbital reshaping burns and less drifting time, keeping tanks cooler and venting less propellant.
25. In the original plan, Starship could carry full tanks for days while traveling to NRH, letting propellant sit idle and boil away.
26. In the streamlined plan, fuel is used earlier for major burns such as trans‑lunar‑injection and lunar‑orbit insertion, minimizing idle storage.
27. Shifting schedule‑sensitive mission phases closer to Earth widens launch windows; Orion only needs to reach LEO first, making launch timing more forgiving.
28. Starship can remain on‑orbit awaiting rendezvous later without forcing a full mission reset if delays occur.
29. The crew launch (Orion on SLS) is separated from the rest of the mission, allowing independent Starship launches.
30. Future missions could substitute Orion with other crew vehicles (e.g., Crew Dragon or a crew‑rated Starship) while retaining the LEO rendezvous model.
30. Safety improves because problems near Earth are easier to manage, inspect, or abort from than those discovered in distant lunar space.
31. The Orion‑on‑nose concept provides roughly 600 cubic meters of habitable volume in Starship HLS, far more than Orion’s capsule.
32. Greater habitable volume allows astronauts to move, exercise, store supplies, and maintain more normal daily routines.
33. Dedicated areas for rest, privacy, and operations can reduce stress during the multi‑day deep‑space transit.
34. With Orion and Starship docked, the crew has two functioning spacecraft; Starship can serve as a backup habitat if Orion encounters life‑support or avionics issues.
35. For Boeing, the new plan reduces SLS’s role to merely placing Orion into LEO, diminishing its need for costly upper stages like the interim cryogenic propulsion stage and the exploration upper stage.
36. This downgrade represents a financial and reputational setback for Boeing’s space business, given SLS’s history of delays and budget overruns.
37. The shift validates SpaceX’s reusable launch model, as NASA would rely more on a system designed to refuel, fly again, and scale operations over time.