SpaceX F9 - Anasis II - SLC-40

[Cosmacelf]

Yes exactly, buffer the data until you can reliably transmit it. I've been wondering why that wasn't a fix for the drop outs long ago

My guess, the same reason for many things at SpaceX and Tesla. They are growing so quickly and doing so much mission critical innovation, that they just haven’t had the time to implement this “nice to have” feature. I mean, it was only a month ago at Tesla that they finally released the “don’t auto lock my car at home” feature, seven years after walk away door locks.

Or, and this would be cool, they are now using Starlink

 

[ICUDoc]

Yes exactly, buffer the data until you can reliably transmit it. I've been wondering why that wasn't a fix for the drop outs long ago

I thought the camera was unable to cope with the shaking, so buffering wouldn't help?
Or is it the transmitter that can't cope with the shaking?

 

[Cosmacelf]

I thought the camera was unable to cope with the shaking, so buffering wouldn't help?
Or is it the transmitter that can't cope with the shaking?

I always thought it was the transmitter. In the past they’ve released video of drone landings after they’ve brought the drone ship back to port and were able to access the camera’s local flash storage.

And I could be wrong, but in today’s landing, it looked like the video paused on the live feed for a little while and then resumed.

 

[Cosmacelf]

So, this is really a classified military mission for South Korea, right? Essentially a spy satellite (as far as we know)? Edit: I guess it is described as a military communication satellite...

It just occurred to me that with all these important worldwide launches that SpaceX does and the worldwide footprint of Tesla, Elon can literally pick up the phone and personally call any world leader and they will take his call.

 

[MyJoule]

I always thought it was the transmitter. In the past they’ve released video of drone landings after they’ve brought the drone ship back to port and were able to access the camera’s local flash storage.

And I could be wrong, but in today’s landing, it looked like the video paused on the live feed for a little while and then resumed.

While I'm no expert, the reason for the drop out is likely that the transmission is a Line of site microwave, and the vibration upsets the signal path ( or the plume obscures it?) Anyway, by building a bigger buffer into the camera/ link, they can "coast" through the drop outs and send the data once the link restores. That's my guess at least.

And how cool that they were able to catch both faring halves today. Way to go SpaceX. Always pushing for perfection.

 

[e-FTW]

A few of us have noted the odd pulsating of the mylar (?) covering on the second stage during the burns. I still wonder if someone has explained it...
Look here at T+3mins onwards:

 

[e-FTW]

If B1058.2 launches anytime before July 23rd, it will be the shortest turnaround time on a booster at around 6 to 7 weeks.

And it happened: new booster turnaround record by a couple of days! 51 days from launching humans to the ISS on May 30th to this sat on July 20th.

 

[bxr140]

I still wonder if someone has explained it...

I haven't seen anything.

I'm not sure if I said it in this forum or not, but a few observations I've made is that the whole thing kind of inflates with a bang, soon thereafter has another inflating bang, and then once the more localized pulse/heartbeat starts it progressively slows down in frequency over time.

Its possible there's some gasses intentionally bleeding off, but it seems really odd to me that anything would be plumbed to exit under the MLI. Of all the various paranoias in the space industry, MLI not staying where its supposed to stay ranks as one of the most cereal. Flip side, the fact that its consistent obviously means its supposed to do that, or at least its an acceptable dynamic product of whatever's small gas release is happening in there.

Noodling on causes, its possible there is some thermal correlation. TOTAL speculation here, but one could imagine what little air molecules are left under the MLI (and in the layers of the MLI) are being excited by some rapid thermal exchange--such as the turbo pump and chamber heating up (correlating to the two inflations?).

Also vaguely plausible is if there's some restraint on the gimbals that needs to be released and there's some pressure related aftermath (pyros, gas, etc.).

The progressively slowing heartbeat is a little more perplexing.

Best to Tweeters Elon.

 

[ecarfan]

On Twitter, @Spacex just posted videos showing the fairing halves landing in the nets. They just barely caught them, but they did it!

 

[Cosmacelf]

On Twitter, @Spacex just posted videos showing the fairing halves landing in the nets. They just barely caught them, but they did it!

Nice! Unless I am missing something, it does not look that there is any control mechanism for the parachutes. It looks like they are just free floating. If so, I now understand why they have had such a hard time catching them. Modern square parachutes are very maneuverable and can easily hit a five meter target (with skilled operator). When landing on a target, a skydiver will be making very fast rapid twitch control adjustments to account for the very quickly varying wind.

But if all you have is a boat steering under power, that is a hard problem indeed.

 

[adiggs]

On Twitter, @Spacex just posted videos showing the fairing halves landing in the nets. They just barely caught them, but they did it!

Got a link to those videos? I'm not a twitter user (not even an account), but I'd sure like to watch those videos.

 

[mongo]

Got a link to those videos? I'm not a twitter user (not even an account), but I'd sure like to watch those videos.

no account needed:
https://twitter.com/spacex

 

[adiggs]

no account needed:
https://twitter.com/spacex

That is awesome

 

[ecarfan]

Unless I am missing something, it does not look that there is any control mechanism for the parachutes. It looks like they are just free floating

My understanding is the fairing chutes are steerable.

 

[ICUDoc]

the fairing chutes are steerable.

Wow, how the heck do they do that?
Does anyone know what a fairing costs to build? I seem to remember it's carbon fibre?
So suddenly there's another $Xmillion off the cost of a launch. And less waste / more re-use.
Go, you good thing...

 

[adiggs]

Wow, how the heck do they do that?
Does anyone know what a fairing costs to build? I seem to remember it's carbon fibre?
So suddenly there's another $Xmillion off the cost of a launch. And less waste / more re-use.
Go, you good thing...

I remember Elon using an analogy of having a pallet with $6M tossed out of an airplane at high altitude. Do you just ignore it and let it sink to the bottom of the ocean, or do you put some energy into trying to retrieve it - any of it.

Unclear to me if that is $6M per piece, or for the pair

EDIT: To be clear, I have no actual knowledge, experience, or anything else that is useful from an objective point of view. Just a memory of something Elon might or might not have said.

 

[Cosmacelf]

Wow, how the heck do they do that?

Exactly. I see no mechanism for steering on those videos.

Normally, on a "square" (they are rectangular, of course) parachute, you have two control lines that go from the base of the risers all the way to the back of the parachute. Each control line can "close" or pull down one side of the back of the parachute. You use them to change the airfoil shape of the parachute. Think of the control lines as adding or removing flaps from an airplane wing.

To steer right, you would pull down on the right control line, giving the right side more flaps which causes less airflow on that side, causing a downward spiral towards the right. Both control lines all the way up give the most forward speed, but also fastest descent. You can slow down forward speed and slow descent by pulling down on both control lines to right before the stall point (yes, you can stall parachutes).

Here you can see a skydiver with both control lines all the way down. The chute is definitely in a stall, but that's what you do for landing. I forget how far above the ground you typically do this at, but at some point, you stall the chute just before landing and you literally do a tip toe stand up landing.

So, the control lines typically have travel from human arms all the way up to human arms all the way down. The not stall range is probably about 4 feet of travel.

So, to actively, remotely, control a parachute, you'd need to have a motor mechanism that can rapidly move the control lines up and down. And some sort of battery pack for power. I saw no evidence of either control lines or motors for this in the videos above.

To be fair, writing software to autonomously control a steerable parachute would be ... challenging

 

[Cosmacelf]

Then again, this article says "a GPS-equipped, steerable parachute (called a "parafoil") will deploy approximately 5 miles (8 km) above the water."

Meet Mr. Steven, SpaceX's Rocket Nose-Cone-Catching Boat | Space

So what do I know? I would be interesting to know how they are steered.

 

[Cosmacelf]

OK, if you look at this image blow up:

You can see two thin lines going down into the inside middle of the fairing. Could very well be control lines and thus attached to motors inside the fairing itself.

 

[mongo]

I was slow to complete, so this is fairly redundant
...

Yep, 6 million for the pair with steerable parafoils
SpaceX returns intact fairing half on clawboat in post-launch surprise

The video of the fairing entry appears to show multiple lines to the foil.