Earth-Sun L4 and L5 Lagrange points

I understand these are at 60 degrees ahead of, and behind, Earth (respectively). Does anyone know how much harder it is to keep satellites at other ‘offsets’ from Earth? Could we realistically also have one at 30 degrees, one at 90 degrees, one at 120 degrees, and one at 150 degrees?

And could it be beneficial to send data via that route? Could they play a role analogous to something like this?:
https://en.m.wikipedia.org/wiki/Optical_communications_repeater
Or would it just be a pointless increase in latency for no benefit?

My uneducated guesses:

1. Starlink’s existing provision for Earth could be achieved for Mars too, using a very similar system
2. In some ways, Mars will be easier.
   1. Much thinner atmosphere
   2. Far fewer of the constraints needed to ‘play nice’ with an existing high-tech civilization, like minimizing reflections of sunlight to the ground, or avoiding radio interference.
3. But the first generation system for Mars will be different in an important way: significantly higher altitude
   1. Thus higher ping times
   2. And fewer satellites than would otherwise be needed for continuous coverage, which in turn means lower total bandwidth capability, and less redundancy, but much cheaper & quicker to set up and maintain.
4. None of the above covers the actual NASA requirement/aspiration for new interplanetary comms (which seems to be referred to as “DRM 4”).
   1. For one thing, an in-space laser link that can cover 100s of miles efficiently, is qualitatively different from one that can cover 100s of millions of miles.
   2. But as NASA has already achieved over 6 Mbps across 240 million miles, SpaceX will also be able to create a usable interplanetary link
5. SpaceX will equip some of their Earth-orbiting Starlink satellites, and all of their Marslink satellites, with this qualitatively different, and outward-facing, laser comms tech.
   1. Having, as your endpoints, devices that are orbiting around planets, is disadvantageous in some ways, such as the fact they spend about half the time on the wrong side.
   2. But SpaceX will find a way to make it into an advantage. (Multiple simultaneous connections?)

Any thoughts?

Also, you need a relay capability when the sun is in the way. But are such relays expected to be beneficial even at other times? Will SpaceX find a way to make them beneficial?

P.S. It’s interesting that Spaceflight Now did a tweet thread on this NASA presentation, but didn’t consider it worth an article. Yet PC Mag made a whole article primarily out of 1/3 of a slide from one of those tweets by Spaceflight Now! (And I’m glad they did!)

Also onboard is the ARTEMOSS experiment, which is pronounced similarly to “Artemis” in a nod to NASA’s Moon-bound program. The acronym stands for “From Antarctica to Space: Molecular Response and Physiological Adaptation of Moss to Simulated Deep Space Cosmic Ionizing Radiation and Spaceflight Microgravity.”

Shouldn’t that be FATS:MRPAMSDSCIRSM?

Nestled inside the trunk of the Dragon is a device called CODEX (COronal Diagnostic EXperiment), … the device will be unpacked and installed using the Canadarm-2 robotic arm.

I’ve been wondering why this mission couldn’t just dock to the zenith port. Could this be why? Is there better access for the arm at the forward facing port? (For those who didn’t know, Crew-9 had to relocate Dragon Freedom to the zenith port a couple of days ago, to free up the forward port for CRS-31.)

(And just to be clear, I have many problems and potential concerns about Musk. I’m just saying I’d choose him over, say, a Maoist, or a Stalinist, and over “Burn_The_Right”.)

How do we remove this cancerous cyst?

I think your username gives us a clue what you would do to Musk and others if you ever gained any power.

I would entrust the wellbeing of humanity to him, over you, without hesitation. We had enough of your type in the 20th Century, thanks.

I would not have thought it could float in a different orientation

Me either. But they call that orientation “Stable 1”, possibly implying they’ve accounted for other stable orientations, and some non-stable situations.

Here was the first time I heard that term (with Bob & Doug): https://www.youtube.com/live/tSJIQftoxeU?t=6h29m34s

The commentator then gives some explanation.

Post-splashdown news conference: https://youtu.be/gOUoI-UYi2Y

They mentioned that Cargo Dragon sometimes reuses parachutes, which I didn’t know.

Watched some of the official coverage: https://www.youtube.com/live/5CRB3FHV9Dw

Things that were new to me:

• 1:40:50 Drone footage of the capsule lift
• 34:42 Jones explains that the same set of 12 hooks secures Dragon to either its nosecone or to the ISS. Makes perfect sense; I’d just never thought about it before.
• 1:35:57 “There are multiple options so if Dragon were to splash down in a different orientation they could egress from the top hatch as well.”
  • Would this be a last resort after they’d tried & failed to correct the orientation?
  • Would it only be used when Dragon was still in the sea or would they ever lift Dragon onto the boat in an orientation that necessitated top hatch egress?

And all this talk of Dragon orientation, combined with the extensive weather delays in Crew-8’s departure, got me wondering … How would Dragon fare if it was left in very rough seas for an extended period? (Imagine the recovery vessel broke down a minute after splash-down and then a big multi-day storm blew in, or something.)

that the engines relight multiple times in orbit

Should they do an orbital test next? Or continue with the previously used ‘almost orbit’ trajectory that ensures the second stage re-enters safely with no need for a relight?

The SpaceX officials in the audio said they were “trying to focus on booster risk reduction versus ship envelope expansion” for the next flight.

For the “ship envelope expansion”, do you think they will/should do an in-space engine relight test? Or are the seemingly successful flip-landing maneuvers on flights 4 and 5 sufficient? (Has this been covered elsewhere?)

Interesting! They’re talking about unnecessary aborts, and how they want to do as much analysis as possible of the abort criteria, to prevent them.

This will remain an issue for Flight 6 which, it seems, will happen the moment SpaceX decides it’s sufficiently ready. Unlike previous flights …

“Given this is the first launch in a long time … well really ever … that we’ve not been FAA driven …”

This would be a nuclear option and, in reality, probably would do more harm than good to SpaceX,

It would probably set back their more ambitious targets by decades. But even Starship is now far enough along to no longer really need Musk’s stewardship, and the US government would be happy enough just with control of the Falcon programme. They don’t care much / at all about Making Life Multi-Planetary.

So I consider a move like this pretty plausible.

One of my favourite videos of the catch, because of what happens when the sonic booms arrive!: https://youtu.be/749dRxbSkVU (They’re at 6:51.) Also it’s a different angle from most of the others, because it’s from Mexico.

And a playlist: Starship IFT5 booster catch, original footage only

You heard it on Lemmy first!: https://sh.itjust.works/post/25840892 (very soon after Stich first mentioned it)

Link currently doesn’t WFM.

I believe when you create a clip from an ongoing YouTube live stream, it will (at best) only work as long as the footage you selected is still available on the stream. And I believe YouTube only keeps the most recent 12 hours of footage.

(What they should do is create a permanent copy of the relevant footage, assuming the channel owner permits it.)

The fairing looks spotless. I guess they’re using a new one, at least partly for reasons of cleanliness? (Planetary protection and all that.)

With boosters we’re at the point where “flight proven” is no longer just a euphemism for “second hand”. I’ve felt that way myself for a few years. And NASA basically confirmed they agree a couple of months ago, when the brand new booster intended for Crew-9 was given a Starlink mission first, increasing confidence in it after a minor problem during transport. (IIRC)

But I’m not sure if we’re at that point with fairings. Or even if we’ll ever be.

I like SpaceX’s Sarah Walker, despite (or partly because of?) the fact that she tends not to answer questions from mere mortals (non-SpaceX / non-NASA personnel).

For example, at the Post-Launch News Conference, there was a question about pulsive splashdown (although that term was not used).

She seemed to imply that the capability would have been available for Crew-7 if it wasn’t for a problem with one of the GPS sensors. (Was this problem known about well in advance of undocking? Would that be why they didn’t announce the new capability at the time?)

She spent most of the time confirming the point I made in my first comment on this post, about taking into account any extra risks that this capability might add, and she said that it had taken “years”.

She didn’t answer whether it’s available if the parachutes fail during a launch abort, nor tell us any of the (non-NASA) missions it has been active for (of which Gerst had said there were “several”).

Here’s the question: https://www.youtube.com/live/wwhfph1vGdE?t=32m30s (at 32:30)

When composing the title of this post I nearly called this technique ‘Propulsive Splashdown’, but I didn’t remember ever hearing that term used before. (Stitch didn’t call it that, did he?)

Later I heard Stephen Clark use that term in his question. And yesterday that term was used during the launch stream. Nail and Cardman spent a minute discussing the capability: https://www.youtube.com/live/SKXtysRx0b4?t=3h29m8s (from 3:29:08)

Apparently they often abbreviate it to “prop splash”.

At 52:05, Stephen Clark asked about this. The start of Gerst’s answer is:

We’ve actually flown it on several other dragon flights before this. This is the first time it flies on a NASA mission.

So, perhaps Inspiration 4? Presumably Polaris Dawn? And I guess the Axiom missions are being counted as non-NASA in this context, so some of those?

Before doing something like this I think you should ensure that it reduces the overall risk to the crew. So you’d need to have an estimate of how likely it is that all the parachutes fail, and how likely it is that the SuperDracos could save lives in that situation, but also an estimate of how likely this capability is to go wrong. For example, could there be a bug in the software or in some sensor(s), that causes the SuperDracos to fire when they weren’t needed? Would the SuperDracos otherwise be in an inactive state during re-entry, and if so, what are the risks of having them active? Etc…

Those 2 sentences from Gerstenmaier suggest to me that SpaceX had already decided that, on balance, this capability should be enabled. Whereas NASA have only just reached that conclusion.

as far as I’m aware, they’ve done 1 EVA to look at the thing

Don’t think so.

They do have access to camera imagery, but as you say, most problems like this probably need much more intrusive investigation.