One hopes, at least, that the companies and consortia developing next-generation LEO space stations will positively festoon them with docking ports.

It is telling, I think, that the current designs of both Axiom and Orbital Reef are, indeed, positively festooned with ports.

Even Starlab, which is a single launch station, has multiple ports — looks like, three of ’em. Likely sufficient for a station that small.

The next Cygnus is to be a new, larger version called the Mission B variant that will fly on the first flight of the new Antares 330. Neither new vehicle is likely to be done on time, and relying on the first flight of a new vehicle from a fairly inexperienced provider (Firefly) is really cranking up the risk.

Firefly has at least been to orbit — and, now they’ve been to the lunar surface. I think Northrop made a reasonable risk assessment in partnering with them. I think any likely alternative they might have pursued would have taken longer and cost even more.

But yes, rocket development programs have a way of sliding right.

ISS has another cargo vehicle, and it even uses a CBM hatch: the Japanese HTV. Unfortunately, it uses the H-2 launch vehicle and is no longer available. Its replacement, the HTV-X, uses the new H-3 launch vehicle, but due to delays in both the H-3 and the HTV-X, it’s not available yet. The latest schedule from Japan has the HTV-X’s first flight in October. Let’s hope it holds.

”It will be at least half a year before the next Cygnus will be ready for launch.”

At least. The next Cygnus is to be a new, larger version called the Mission B variant that will fly on the first flight of the new Antares 330. Neither new vehicle is likely to be done on time, and relying on the first flight of a new vehicle from a fairly inexperienced provider (Firefly) is really cranking up the risk.

”The loss however of this Cygnus cargo mission…frees up a slot in the cargo schedule [for Starliner].”

Unfortunately for NASA and Boeing, no, it doesn’t. Cygnus uses a CBM hatch and must berth to one of two nadir cargo berthing ports. Starliner uses an IDSS crew docking port and must dock to one of two IDAs. The two are not compatible.

”In the meantime, NASA has no redundancy for getting cargo to ISS, and must rely entirely on SpaceX and its Dragon cargo capsules.”

Unfortunately, it can’t do that either. The next cargo Dragon after this upcoming one, launching in August, is a long-duration engineering test of a Dragon trunk-based propulsion system designed to take over orbital reboost of the ISS should the Russian Service Module fail. It will tie up the forward IDA from just after Crew 10 departure in July to just before Crew 12 arrival next March. The Crew 11 Dragon will occupy the only other IDA. (This is the reason Crew 11 runs from July 2025 through March 2026 and why Crew 10 is so short.)

So, no, NASA can’t just order up another Cargo Dragon to make up the shortfall. Like I said, quite a bind. If only we had a third IDA…