Space-X launches - Observations

[ChrisGreaves]

Aren't we all going to be shocked when one of these taxi-cabs does NOT launch and deploy and land?!!
In the meantime, a recent launch provided two interesting side-views.
(1) Fairings seen from the booster: I am used to seeing the fairings whizz by the booster, but in this launch (3m34s after launch, 15m25s in the video) the two fairings were seen relatively close together.

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(2) Just before landing of the first stage (7m15s; 18m55s) the booster appears to descend down the column of its launch exhaust, created not even eight minutes prior to this passage. I don't recall seeing that before. Of course this was not a landing-at-sea.

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Question 1: I thought that US rockets took off in a general eastward direction. Why do Florida launches land at sea whereas this launch from California, lands on, well, land?

Question 2: Booster landings are a piece of cake (it seems to me) compared to faring captures. Boosters are big enough to carry propulsion systems and computers, and have a lovely bulls-eye at which to aim (although perhaps the bulls-eye is just tradition, GPS being a better aiming device) whereas fairings are jettisoned accurately in terms of time, but over a greater variation in distance, have no guidance system (that I know of), and so some poor skipper-at-sea has to get his boat to the right spot either to capture the fairing(s) in a hammock, or at least to fish them out of the briny before they sink. Why wouldn't SpaceX show us this more demanding task once in a while?

Cheers, Chris

[PJ_in_FL]

Both your your statement-questions contain errors.

The Florida launches use Earth's rotation to add to the lateral velocity of the vehicle. Where the boosters land, if at all, is a function of the amount of thrust needed for the launch.

California launches are generally for polar orbits. Boosters from that site use both RTLS and land at sea,

Fairing catches would be boring.

[ChrisGreaves]

Both your your statement-questions contain errors.

Story of my life!
But thanks for pointing them out and clarifying the issue.

The Florida launches use Earth's rotation to add to the lateral velocity of the vehicle. Where the boosters land, if at all, is a function of the amount of thrust needed for the launch. California launches are generally for polar orbits. Boosters from that site use both RTLS and land at sea,

This makes sense to me. It is niot so much the site that governs the landing, but the intended orbit. If Vandenburg is used as the "polar" orbiting launches, then Vandenburg is going to have more LANDings than a site that is used for equatorial launches.

Fairing catches would be boring.

If that's all they showed, well, yes. But early attempts to capture fairings with a hammock mounted on a boat had failures It would be interesting to see a fifteen-second clip of how they are doing it now; especially since (I think) the fairings themselves have no power or guidance systems.
I think there were efforts made to capture parachute or balloon packages using a cable hung from an aeroplane. the cable snagged the shrouds.

As one who grew up with the Sputnik Launch, I have maintained my interest in launches, and still follow the Space-X launches, but they are now becoming boring to the extent that I follow the launch for the view-from-the-air in the first minute of the launch, then fast-forward to the fairing separation and fast-forward to the landing. I put it to you that for this viewer, the launches are becoming boring!
Cheers, Chris

[PJ_in_FL]

... If Vandenburg is used as the "polar" orbiting launches, then Vandenburg is going to have more LANDings than a site that is used for equatorial launches.

Incorect.

Two factors govern the landing site:
1. How much boost from Earth's rotation is obtained during launch.
2. How much energy is needed to get the payload to it's intended orbit, and that's a factor of altitude and weigh of payload. Some polar orbiters are quite large.

So fewer or more depends on several factors that can't be predetermined by past performance, much like stocks.

As one who grew up with the Sputnik Launch, I have maintained my interest in launches, and still follow the Space-X launches, but they are now becoming boring to the extent that I follow the launch for the view-from-the-air in the first minute of the launch, then fast-forward to the fairing separation and fast-forward to the landing. I put it to you that for this viewer, the launches are becoming boring!
Cheers, Chris

Shuttle launches became boring, until they weren't.

[ChrisGreaves]

So fewer or more depends on several factors that can't be predetermined by past performance, much like stocks.

I agree; absolutely. I supposed "all other things equal". Possibly even a spate of Newfoundland weather in oone launch site might cause a scheduled launch to take place at another facility - although that would then involve transporting a Clean Payload 2,000+ miles.

Shuttle launches became boring, until they weren't.

Quite true, and we shall probably see deaths within our lifetimes.
Cheers, Chris
(later) but then, but then, ... Clearly boosters are able to return to their point of launch, so far always on land, so it seems to me that any launch should be able to return to land. Perhaps a boat landing means that the booster doesn't have to travel so far back, a saving in distance and hence fuel load, just stop-and-drop, and use the fuel-efficient boat to tow us back to harbor. C

[ChrisGreaves]

Question 1: I thought that US rockets took off in a general eastward direction. Why do Florida launches land at sea whereas this launch from California, lands on, well, land?

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This is the kind of imagery that makes me wonder. A screenshot from a recent launch video.
I take it that the white dot indicates stage separation and the booster's return to earth, which appears to be near-vertical, and this landing was on a drone ship. The distance from the coast (Cape Canaveral) seems enormous, and to land back at Cape Canaveral would take a serious amount of energy. The horizontal (eastwards) component must be brought back to zero, and then an equivalent westward component invoked, and finally this westward component brought back to zero. That is a lot of energy, and much that can go wrong - two direction reversals.

Perhaps it is that rotational fling eastwards that brings about this massive cost; without that eastwards rotational component, a straight polar launch would have a shorter return to Earth, and so the launch site (on land) is easier to reach?
Cheers, Chris

[PJ_in_FL]

The vertical line indicates the instantaneous altitude of the spacecraft. The line below the arc shows the ground path. SpaceX usually shows the different projected tracks of the various components, e.g. booster, second stage and satellite, separately, as the three arcs to the right probably are.

[ChrisGreaves]

Question 1: I thought that US rockets took off in a general eastward direction. Why do Florida launches land at sea whereas this launch from California, lands on, well, land?

Documentation surrounding a November 2023 launch provides me with more food for thought.

"Liftoff from historic Pad 39 at the Kennedy Space Center in Florida came at 8:28 p.m. EDT, roughly the moment Earth's rotation carried the seaside firing stand directly into the plane of the space station's orbit. That's a requirement for rendezvous missions with targets moving at more than 17,000 mph."
I recognize that Bill Harwood writes "a requirement"; my logic tells me that if more fuel were added, then there would be an option to adjust the orbit after launch and navigate the cargo craft to the ISS docking orbit. Of course, the further away the initial trajectory is from the optimum trajectory, the more fuel needs to be lifted to orbit for the in-orbit navigational phase, and thus the more fuel needs to be used in the booster, which leads to ...
In the limit, launching he cargo missile in a polar orbit when the ISS ois in an equatorial orbit would be a stupid expense/cost.


"The first stage booster, also making its second flight, flew itself back to the Cape Canaveral Space Force Station to chalk up SpaceX's 39th Florida touchdown, and its 243rd overall."

This too was puzzling me (but I can't find my thread where I raised the question). If a booster can make its way back to a launch site, then a booster can make its way back to its launch site.(sic) I think my original question came up with a launch from California and a launch from Florida. I believe that some of the Florida launches land at sea, while some return to land on Florida dry-land.
My guess is that it is cheaper to tow a barge-with-a-booster two hundred miles or so, than to add the extra fuel required to navigate a re-entering booster back to dry land.

If launches from California are in the eastward (Earth's rotation) direction, then I suppose that one would rather try to return to base rather than guarantee that you won't hit Reno, Boise, or Salk lLke City accidentally.

And yes, perhaps I should be emailing Bill Harwood.

Cheers, Chris

[Graeme]

Speaking of Space X launches, this should be fun, if the regulatory permissions are granted:

https://www.space.com/spacex-starship-l ... ember-2023

Graeme

[Graeme]

Also, 17 November is the peak of the Leonids Meteor shower.

Graeme

[ChrisGreaves]

https://www.space.com/spacex-starship-l ... ember-2023

Thanks Graeme.
To my parochial mind a 400-foot structure is alike unto a 40-storey building!
Cheers, Chris

[Graeme]

What time is Starship launching?
SpaceX is aiming for a 20-minute launch window starting at 8am EST (1pm GMT) on 18 November. A livestream of the launch will begin half an hour earlier, at 7.30am EST (12.30 GMT). The launch was originally planned for 17 November but has been delayed to replace a part, Musk said.

https://www.youtube.com/watch?v=m-LFzFWaACo

[Graeme]

T - 1 hour 30 Minutes to the second test launch of the biggest rocket ever made!

Live view:

https://www.youtube.com/watch?v=m-LFzFWaACo


Graeme

[ChrisGreaves]

T - 1 hour 30 Minutes to the second test launch of the biggest rocket ever made!

Perfect Timing!

I am re-reading "Martian" by Andy Weir. This book is one of three fiction books that I have shelved in my reference section in the Dewey 530 sequence - Physics.
Cheers, Chris