The most traveled crew transport spacecraft flies again | Hacker News Reader

The most traveled crew transport spacecraft flies again

arstechnica.com

62 pointsrbanffy18 comments

I was surprised it wasn't one of the Shuttles, but Discovery's record there was a tiny bit over a year; 365.96 days in flight. (Quite a few more flights, though; 39.)

IMHO the number of flights seems like a much more important metric of durability, since virtually all the stress will be imposed on the frame during launch and reentry. It doesn't make a huge difference if you spent 8 or 180 days docked to the ISS in between.

It kinda does though. The ISS orbits every 90 minutes or so. Meaning it cycles from very-hot to very-cold.

Doing that for 180 days means thousands of cycles. While not as violent as take-off and landing, it's a factor that can lead to metal fatigue and so on.

Quite how big a factor remains to be seen, hence the fairly strong observance, and testing of parts (earthside) after they return.

If that's what's important then the ISS itself has beaten it. So it still seems like an arbitrarily narrowly chosen record just to make it seem special by limiting it to transport spacecraft. Everything beats some sort of record if you exclude enough others.

I wonder if a deployable sunshade would help extending their life. When Skylab lost one solar panel array on launch, they had to cover it with a blanket to help manage temperatures.

launch/reentry are of course huge stressors, but IIRC just being docked subjects a spacecraft to a larger temperature range than you might expect. From NASA:

> Without thermal controls, the temperature of the orbiting Space Station's Sun-facing side would soar to 250 degrees F (121 C), while thermometers on the dark side would plunge to minus 250 degrees F (-157 C).

That's a lot of thermal expansion/contraction, every 90 minutes. I'm not sure if that actually adds up to being equivalent to the much larger # of launches/reentries that discovery underwent, but it's _something_.

That has its own issues as a metric, since the Shuttles were much more fragile and had to go through much more refurbishment compared to Dragon.

I guess that's why the Space Shuttle was called the Space Shuttle: it dropped astronauts (and supplies) off at the ISS and then returned to Earth with the previous batch of astronauts (this seems to have been a typical "ISS mission": https://en.wikipedia.org/wiki/STS-105 - mission duration ~11 days; the commander, the pilot and two mission specialists flew there and back, while three mission specialists were dropped off/picked up). Whereas a Crew Dragon capsule stays attached to the ISS for as long as its crew is there, similar to (most of) the Soyuz capsules.

The "shuttle" concept dates to the late 1960's. Great marketing, but the program was intended to finish once a destination was built.

https://en.wikipedia.org/wiki/Space_Station_Freedom

> As the Apollo program began to wind down in the late 1960s, there were numerous proposals for what should follow it. Of the many proposals, large and small, three major themes emerged. Foremost among them was a crewed mission to Mars, using systems not unlike the ones used for Apollo. A permanent space station was also a major goal, both to help construct the large spacecraft needed for a Mars mission as well as to learn about long-term operations in space. Finally, a space logistics vehicle was intended to cheaply launch crews and cargo to that station.

https://en.wikipedia.org/wiki/Space_Shuttle_program https://en.wikipedia.org/wiki/STS-134

> The Shuttle was originally conceived of and presented to the public in 1972 as a 'Space Truck' which would, among other things, be used to build a United States space station in low Earth orbit during the 1980s and then be replaced by a new vehicle by the early 1990s.

Well, you could say that those plans were ultimately accomplished, although much later and in a different form: the shuttle was used to build a space station (the ISS - not in the 80s, but in the 2000s) and was eventually replaced by a new vehicle (again much later, in the 2020s, with an embarrassing gap in between, and the new vehicle looks much like the shuttle's predecessors - but still...)

This is mostly because NASA wants there to be an escape seat for every astronaut in case of an emergency that forces the evacuation of the station (or say, a medical emergency). Even if they want to relocate a Dragon to another port, everyone who rode that capsule has to get back in for the relocation, so they always have a way back down.

During the space shuttle era, initially this wasn't a concern as the plan was to have the crew stay in one module until a rescue vehicle could arrive, but after Challenger, there was an extra Soyuz for that purpose.

And here I was thinking it was about Soyuz, which hasn't really stopped flying.

Individual Soyuz spacecraft are expendable, they need to build a new one every time.

According to [1] here have only been two Soyuz launches since the start of 2023. SpaceX recently did more launches in one day.

[1] https://en.m.wikipedia.org/wiki/List_of_Soyuz_missions

Every word in this headline is doing some work here.

Crew Dragon doesn’t have the most trips to space, it’s just the entry/reentry vehicle with the most time in orbit.

That seems disingenuous given that the shuttle is the only other competition, and had the additional responsibility of providing life support and accommodations for the entirety of many missions, whereas Dragon is only used for transport.

I'm not sure I agree with that last distinction: the Inspiration4 and upcoming Polaris missions are standalone Crew Dragons that do not dock with the ISS, and they're even planning a spacewalk.

Those are also MUCH MUCH shorter than an ISS mission where a Dragon stays docked for months. It's worth weighing the amount of time in space versus the amount of time that the crew is relying exclusively on the vehicle's life support systems. That said, I don't think this is a particularly important point. This capsule has clearly spent a lot of time in orbit, and is likely only 1/3 of its way through its lifecycle (spacex is looking to extend the use to 15 launches). Comparing against Discovery at the end of its lifecycle and after it underwent multiple major refurbishments makes the comparison rather meaningless.

Let's not forget the Shuttles were not as much reusable than fixable. They had to spend months grounded for extensive refurbishing after every flight.

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