Rockets of Today

ORION— USA, 2014/2024?

Orion isn’t a commercial craft — it was developed for NASA as their new Multipurpose Crew Vehicle. It resembles an Apollo capsule, being a cone with a sharp 32.5 degree taper, but is quite a bit bigger, having a base 5 meters wide, and 19 cubic meters of pressurized space... though only 9 of these are accessible crew compartment — the rest holds stuff such as a water recycler, which is necessary for long missions such as visiting a near-Earth asteroid, or eventually Mars. I sure wouldn’t want to live in one for the time it would take to travel that far, but it may not be as bad as it sounds: for Mars at least, the plan is to attach it to some larger habitation module — a bubble, or something more substantial. It seats four, but in theory you could fit six for short missions. The point of this craft is to support longer spaceflights than any other vehicle. Even with no additions or upgrades it can maintain four people for at least three weeks.

To support that long range capability, it needs a heavy service module, weighing over 15 tons fueled, and the capsule brings the total to a hefty 26 tons. It is reusable, though the number of missions that would use it may be small, and for now, all currently planned missions are each getting a new craft. Development of the Orion has consumed an astonishing sixteen billion dollars, making it possibly even more expensive than the SLS rocket which it rides on. And that’s just the cost they admit to — an Inspector General’s report says another $18 billion is hidden elsewhere in the budget, including future costs through 2030.

The builder is Lockheed. At present, this has taken one complete test flight, and a partial version was flown to test high-speed reentry. The service module on the back is made in Europe, and is an awkward misfit as they are reusing a design made for a different craft as their starting point. This module would as usual would be ditched to uncover the heat shield for reentry. It supplies Orion’s propulsion — it has a single large nozzle, plus maneuvering thrusters and solar panels. Without it, the capsule has minimal steering thrusters, like Apollo. It sounds like they’re figuring on making an even bigger service module for the long trips, but nothing specific has been described yet for that. They had hoped to develop a way for it to land on dirt with airbags, but this was abandoned — they’ll stick with ocean splashdown.

As mentioned, the launch vehicle for these ambitious missions is NASA’s SLS. Given the Orion’s heft, it would be tough for any smaller rocket to send it to the moon or beyond — a New Glenn would be the bare minimum, probably. Such a large rocket under a compact capsule means that aiming at nearby targets like the Space Station would be ridiculous, so they aren’t going to bother with anything like that. They sent an uncrewed Orion to orbit the moon on the SLS’s very first test flight. That was scheduled for 2019 but slipped to 2022. (There was briefly some public talk about adding a crew to this mission, but apparently that was just Trump administration ignorance talking.)

Speaking of reusing engines from the shuttle, as the SLS is doing, the motor on the back of the Orion’s service module comes from the Orbital Maneuvering System — the two smaller nozzles you see on the back of the shuttle above the three main engines. They aren’t just copying the designs: on at least one Orion service module — the one used for Artemis 1 — they reused an engine that actually flew in shuttles. It burns hypergolics, and despite its large bell only produces a tenth of a gee for Orion. It also has eight smaller nozzles on the back (besides the tiny thrusters for rotation), and I would have thought those made the large engine redundant, but the craft sometimes has to perform fairly large burns at low altitudes over the moon, and in those cases you don’t want to spread the burn over half an hour — making it quick saves fuel. The total delta-V that the service module can provide is around 1.5 km/s depending on load, which is a lot more than most other spacecraft, though well short of what the Apollo service module had to do.

For launch escape it has an Apollo-style external tower... which adds another seven tons, including the fairing which covers the windows during ascent. (It has four rectangular windows of high optical quality in the walls, plus little ones on the door and the docking hatch.)

There was also a parallel project in the early part of Orion’s development which was called “Orion Lite”. This eventually, after changing hands a couple of times, became the Boeing Starliner, after they threw out the Orion heritage and started clean.