The Great Ongoing Space Exploration Thread

Look. I tell you what. Those who want to can eat Johnson. And you, sir, can have my leg. And we make some stock from the Captain, and then we’ll have Johnson cold for supper.

I’m sorry, sir, this is abuse.

Not a good week for upper stages! Looks like SpaceX experienced a failure on tonight’s Starlink mission:

Will be interesting if they can salvage the mission anyway.

People noticed some strange goings-on during the mission. The initial upper stage burn looked ok, but at a certain point the thermal blanket puffed out, ruptured, and started leaking oxygen ice. There’s always a little bit of ice, but this was much more than usual. Seems like there was a small failure during the first burn, which somehow caused the engine RUD on the second.

This will definitely throw a kink into their flight schedule. They are quick at diagnosing issues but it’ll take weeks at a minimum to root cause.

Probably worth explaining some terms for those that aren’t already immersed in spaceflight.
RUD: Rapid Unscheduled Disassembly. Joke term for “explosion”.
Perigee: The lowest altitude part of an orbit. Apogee is the highest point. Starlink satellites use circular orbits, where apogee equals perigee.

The Starlink satellites here needed two burns to adjust the orbit properly. The apogee seems fine. But the perigee was not raised up to the apogee due to the engine failure.

The satellites do have onboard thrusters, and may be able to complete the maneuver (also called “circularization”). But they aren’t very powerful and the perigee is low enough that it’s in the atmosphere. The air drag may be so great that the thrusters can’t overcome it. But it’s not certain either way yet. The satellites can also put themselves in a low-drag configuration. Basically, aim the solar panels so that they don’t have the flat side pointing forward, since that would act like a sail. That will help but it may not be enough.


The SpaceX statement is a teeny bit ambiguous, first saying “our maximum available thrust is unlikely to be enough,” and then saying that they’ll reenter.

Jonathan McDowell (satellite tracking enthusiast) posts orbital data, and posted this chart of the deployed Starlinks:

That one with a 190 km perigee might just make it. The rest are probably gone–120-150 km is just too low. And honestly I’m not sure why there’s the one outlier anyway. Possibly it’s incorrect. I’ll root for it until McDowell confirms that all are lost, though.

Le sigh:

NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission, began the tests after learning that some of these parts may not withstand the radiation of the Jupiter system, which is the most intense radiation environment in the solar system.

The issue with the transistors came to light in May when the mission team was advised that similar parts were failing at lower radiation doses than expected.

The Jupiter system is not the place to find out your transistors can’t withstand enough rads.

I don’t see how they can fix this without a major delay.

Ew, with a gammy leg?

What kind of rads are we talking about around the Big J? Stuff like high energy electrons? Protons? Something else? I started a thread in 2001 asking about this, didn’t really get an answer.

And yeah, sucks for that spacecraft. You don’t just pull out ICs and plug in a different spec part. You have to redesign.

We probably have a few posters here better qualified to answer than me. I do know that it’s related to Jupiter’s magnetic field, and is basically the same thing as the Van Allen belts around Earth, just at a much larger scale. So I expect it’s mostly charged particles like electrons and protons that get accelerated. Maybe some heavier ions as well. Not so much gamma/X rays, except what you already get from cosmic rays.

A few x-rays, but not where you would have an orbiter.

The main source of particle radiation is actually from emissions from Jupiter’s moon of Io, instead of the solar wind which populates the Van Allen belts. This includes not only protons and electrons but also sulfur and oxygen as well as sodium chloride and potassium chloride. In the powerful electromagnetic environment of Jupiter’s magnetosphere this produces energetic ions which can do considerable damage to both electronics (especially protons), and instruments, and perhaps even oxidative erosion of moving mechanical assemblies. The close orbit of Jupiter is basically the most hazardous radiation environment beyond the orbit of Mercury.

It is really challenging to build electronics that can survive in that environment, particularly with modern electronics that are generally integrated electronics that are optimized for energy efficiency. Space-rated components are quite expensive because they are low volume and generally low performance, and essentially have only the space application. The Planetary Society article on fault tolerant and radiation resistant avionics design for the Juno spacecraft.


Of course secondary x-rays from the particles striking the spacecraft itself might be an issue.

From what I can find online, Jupiter’s radiation belts are complicated. You have proton versus electron levels, plus plasma blasted off Jupiter’s upper atmosphere and the inner moons. According to Wikipedia Io receives a whopping 36 sieverts a day at its surface, and I understand the radiation is even more intense further in at the orbits of Metis, Adrastea, Amalthea, and Thebe.

There’s a film on HBO of the book, coming out this Wednesday:

The book is When the Heavens Went on Sale; the film is Wild Wild Space. Covers the same material, possibly with a greater focus on Chris Kemp (Astra) vs. Peter Beck (Rocket Lab).

Astra pretty much doesn’t exist now, so we know the winner. Rocket Lab is still kicking. Probably the film has been updated from the book to reflect this fact.

All 20 Starlinks got their Viking funeral.

This is the most successful launch vehicle ever. I will be really interested to see how the investigation shakes out. I would expect it to be ultra-thorough. Their rep and income rely on high-reliability, high-cadence , low-cost launch cycles.

I’m gonna guess manufacturing defect that wasn’t caught and the fix will be increased inspection/testing pre-launch, but that is a truly wild, out of my ass guess. I have absolutely zero information other than what has been made public.

I doubt that rockets in the 1950s/1960s had the level of sensors and bandwidth available now, so post-RUD analysis now is much more likely to pin down the cause of failure.
The Soviet R-7 rocket became the reliable workhorse it was after the USSR launched so many of them that they worked out (almost!) every possible way one could fail.

Counting the entire R-7 family*, the failure rate (either full or partial) is 4.99% (98/1965). That counts all 27 variants of the rocket (from Sputnik through Molniya, Vostok, and Soyuz). That’s over 67 years and 23 built variations of the design - around 29 launches annually .

The Falcon 9 has a failure rate of 0.72% (3/364). That’s over 14 years and 7 variants including the Heavy - around 26 annually albeit heavily weighted towards the last few years (57 in’22, 92 in '23, and 68 so far this year).

In its first 17 years of flight**, the R-7 had a failure rate of 35.5% (37/104) for a cadence of 6 flights annually. Gagarin had balls of fucking steel - that was risky ride on many fronts.

I feel comfortable with my original statement. The F-9 is the most successful launch vehicle ever.

* And to this day, not one is reusable. There are single F-9 first stages that have flown more flights than 10 of the 27 R-7 variations. Not models, actual rockets.
** The stats on the Vostok-K go through 1964 and I didn’t feel like breaking them down farther.

If you count only the active variants–the Soyuz 2.1 has had 145/152 successes, or a 4.6% failure rate. The Falcon 9 Block 5 has had 297/298 successes, or a 0.34% failure rate. So more than an order of magnitude better.

SpaceX is asking the FAA for an early return to flight:

Basically, the FAA only cares about public safety. So SpaceX can ask for a return to flight before their investigation is complete if they can show there’s no public risk.

There’s a good chance they’ll only ask to resume internal (Starlink) flights. SpaceX is happy to take a risk on those, but external customers will probably want the investigation to be completed. Though perhaps not all–the issue here was with the relight, and not all customer payloads require that.

I do wonder, though–the lack of a relight means the stage may reenter anywhere instead of over the ocean. That is a public safety issue. I can see the FAA denying the request on this basis. I suppose it might depend on the odds of it affecting anyone on the ground. Not all rocket stages bother with a controlled reentry anyway. Of course, “the Chinese do this all the time–why can’t we?” isn’t great for PR.