SpaceX Rocket Survives Experimental High-Thrust Landing at Sea | Hacker News Reader

SpaceX Rocket Survives Experimental High-Thrust Landing at Sea

space.com

106 pointsshahocean38 comments

Well that answers the question of why they were following the first stage and why it seemed like it still had its legs (you can see one sticking up in the tweeted photo).

Since I have to guess, I'm guessing it stayed closed up most of the way down, avoiding perhaps even grid fin erosion during high re-entry speeds. It is fun to see a company that has rockets it can expend for experiments like this because it is so far ahead of its nearest launch competitor in terms of costs.

They're not expanding it for experiments. It's just an old model that costs too much to refurbish, and they've got a new one coming up which will be a lot cheaper and easier to refurbish than the current (which is one model ahead of the just-launched rocket).

And once you're throwing it out, might as well do some experiments.

> And once you're throwing it out, might as well do some experiments.

I understand what you're saying here, but the extent to which the aerospace industry just does not work this way is staggering.

This is a fairly unique quality of SpaceX.

.. not to mention the fact that "once you're throwing it out, might as well do some experiments" is not how the incumbent space companies was operating, before SpaceX came along. For them, it was more like "we've got a near-infinite supply of cash from the government, lets just submit another PO for the next round of experiments" ..

Gwynne Shotwell (CEO of SpaceX) stated near the end of this video[1] that the reason they had such good video coverage is that they usually follow the second stage, but in this case it was a classified mission and were forbidden to do so. The cameras followed the first stage return instead.

[1]https://www.youtube.com/watch?v=kjTHJzWPTnU

Those are great videos, in this case I was talking about the launch of GovSat-1 (non classified) which was a launch to GEO so a high delta-v launch. SpaceX has generally defined these as 'unrecoverable' for at least two reasons; the first stage is going too fast making reentry quite 'hot', and they have used all the fuel to boost mass rather than save some for landing.

So when they stood up the rocket and it had landing feet attached I was curious (why waste the weight of those feet if you aren't going to land it?). My guesses were that either it was too much work to remove them (it was a pre-flown booster) or some other experiment. It turns out they were experimenting with a different return profile that could allow them to land this type of mission's booster.

Your "following the first stage" made me think of the Zuma launch footage and I forgot this was about GovSat-1. Nice there are so many going on that it is easy to mix them up.

On further research I think it was the NROL-76 launch with a classified payload in spring 2017 that she was talking about.

So what was the purpose of this experiment? Will SpaceX now attempt to recover boosters from flights to more extreme orbits?

They did the landing burn with three engines instead of usual one. It's more fuel efficient (shorter), which allows for either higher orbits or bigger payloads.

I think it did it over water because they were afraid it would damage the barge.

I believe the barge is also tied up with the falcon heavy launch next week.

I think this is more likely the main reason for the water landing. They have done a least one short three engine burn before using the drone ship.

that's the first rocket in history that was recovered but it wasn't planned to.

Being billed in the media as a failure:

"SpaceX Expendable Rocket Fails" https://perens.com/2018/02/01/spacex-expendible-rocket-fails...

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Eh, you might deserve that hit. ;)

"media"

It's a joke on a guy's blog. The rocket "failed to be expended".

Decode the ROT13 at the bottom of your parent post.

I think we should save this for one that can actually fly again after being 'recovered'.

> Today's launch marked the sixth time that SpaceX has lofted a spacecraft using a pre-flown booster.

Well done SpaceX!

Falcon Heavy launch now scheduled for next Tuesday.

I can't wait. I am so tempted to go watch it in person.

I'm on the other side of the world and even I want to go watch Falcon Heavy launch live ..

Come join us at Jetty Park!

I guess the big question is how badly is the booster damaged by being in salt water?

Pretty badly, apparently. They did look into parachuting them into the sea and recovering them that way, before going to propulsive landing, but the salt water damage is just too much to deal with.

Could they land it in some huge lake?

Freshwater is probably only marginally better and if anything goes wrong the chances that the debris falls on land is much higher. Unfortunately the Great Lakes are too far north.

They land them on a barge. This was an experiment that might have damaged the barge.

Why would they prefer a lake to solid ground? If there was a fuel budget for return to launch site, they’d do that before flying it into a lake. Hell, they’d land it on a patch of grass before dumping it in water. There’s nothing to be gained by making the rocket wet (or a lake all rocket-y, those things are dirty with soot and stuff). They just weren’t sure that it wouldn’t punch a big fat hole in the ship (plus the ship is needed for Falcon Heavy next week), so they’d rather have the rocket get all seawatery than the ship hole-y. As long as the telemetry comes back, who needs an old rocket? Might still learn something from retrieving it but it’s not worth reflying as this booster was an older version that is rather expensive to refurbish.

You’d have to launch it over a lake, but you’re not allowed to fly the first stage over populated areas so it would have to be a very remote huge lake. That’s quite a limiting set of requirements.

These guys used to be dropped into the sea, recovered and refurbished: https://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Boo...

The story I heard was that after splashing down and spending time in the sea, the refurb cost was not much different to a new build cost, possibly even greater.

The solid boosters did, but liquid engines are a whole other ball game.

Do you mean that liquid engines are easier or harder to reuse after being dumped in the sea? Maybe you could elaborate on which difference between solid and liquid engines you're focusing on.

I wondered why my somewhat oldish but still quite usable Thinkpad T42p was stuttering when opening the linked space.com article so I had a look at what it tried to load. Here is the list of domains it loads stuff from followed by the number of requests it makes for different types of resources.

All this for a page which should realistically have been a few KB of HTML, some CSS and a few images. Read and weep:

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   jwpcdn.com
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That’s atrocious, but unfortunately that’s the modern publishing web. I used to be anti ad-blocker, but that was with a somewhat rosy view of advertising networks as not being malicious privacy destroying entities. These days I just block third-party trackers and be done with it.

this is a shame list for the domain space.com. I use uBlock+Noscript and block all scripts + 3rd party domains by default. And when i see more than 5 scripts blocked by noscript, i don't bother myself and don't visit that web page again.

15.95 MB of crap.

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