SpaceX And/Or Rocketry In General

David S
David S
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Clearly, you guys are much

Clearly, you guys are much smarter about this stuff than I am. However, in my own simplistic way, it occurs to me that:

An artificial satellite at a geostationary point above a non-rotating Earth is NOT orbiting Earth only if its position is somewhere on the plane that is 90° to the plane of Earth's orbit of the sun. If the satellite is on any other plane, it will move toward and away from the sun over the course of the year. To me, this means it is somehow orbiting the Earth. [edit](Or does that just mean its orbit of the sun is slightly elliptical?)[/edit]

I hope that A: I am not completely wrong about this; and B: that Mike didn't already say that and I'm too stupid to realize it.

I am aware that I am completely disregarding the energy factors involved.

David

Miserable old git
Patiently waiting for the asteroid with my name on it.

anniet
anniet
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RE: I am aware that I am

Quote:
I am aware that I am completely disregarding the energy factors involved.


I disregarded pretty much everything to be honest... after coming across this bit...

Quote:
...then if I stare at it ( without blinking ? ) for three months say

I need to blink... *blink* ... seeeeeeeeee! :) So decided to opt for no... mainly because there was a fifty percent chance I'd be right :) *sweep other fifty percent under carpet*

But have enjoyed reading about it all immensely :) Learned so much about how much I don't know too... invaluable :) Thanks everyone :)

Please wait here. Further instructions could pile up at any time. Thank you.

Chris S
Chris S
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Any ET mothership will be at

Any ET mothership will be at L3 .....

Waiting for Godot & salvation :-)

Why do doctors have to practice?
You'd think they'd have got it right by now

Mike Hewson
Mike Hewson
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RE: Clearly, you guys are

Quote:

Clearly, you guys are much smarter about this stuff than I am. However, in my own simplistic way, it occurs to me that:

An artificial satellite at a geostationary point above a non-rotating Earth is NOT orbiting Earth only if its position is somewhere on the plane that is 90° to the plane of Earth's orbit of the sun. If the satellite is on any other plane, it will move toward and away from the sun over the course of the year. To me, this means it is somehow orbiting the Earth. [edit](Or does that just mean its orbit of the sun is slightly elliptical?)[/edit]

I hope that A: I am not completely wrong about this; and B: that Mike didn't already say that and I'm too stupid to realize it.

I am aware that I am completely disregarding the energy factors involved.


Your point is valid ie. what counts as an orbit ?

The Earth's orbit around the Sun is slightly elliptic. Slightly closer to the Sun in early January ( perihelion ) and slightly further out in July ( aphelion ). I vaguely remember something about this year's aphelion being closer than usual in the general scheme of things. It's really a multi-body system so such variations from Newton/Kepler ellipses are due to the various planets affecting each other's orbits. There are cycles of various lengths that occur, probably the main long term one is the Milankovitch that primarily is concerned with the inclination of the Earths' rotation axis wrt the orbital plane around the Sun ie. ice ages etc.

Also : most of the angular momentum in the solar system is from Jupiter as it the heaviest planet with a decent 'lever arm'.

L5 is where the ( full ) LISA will/would/could be.

I partly remember a sci-fi based upon an 'anti-Earth' being located at L3 ie. they never knew until a spacecraft found it. It was hiding behind the Sun the whole time ! :-)

L1 has a gaggle of Sun inspecting craft, often to do with 'storm' warnings.

L2 has the Planck mission and other satellites which need to look away from the Sun & Earth.

I don't recall anything for L4.

Cheers, Mike.

( edit ) I'll add that Kepler sorted the ellipse behaviour out over 5+ years of trial & error. He even produced his own tables of logarithms - then new fancy functions for converting a multiplication/division problem to addition/subtraction. And this was while having to defend his mother in a religious court over witchcraft charges ! She got off and then promptly did the right and proper thing ... flee out of the country. You know it's such a good thing that we don't have any modern day counterparts to such mythical* thinking that excludes reality from the inside of people's skulls. Isn't it ? :-) :-)

* If you don't think that sort of thing could possibly happen to you then see Gruen Transfer !!

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

archae86
archae86
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Here is a link with some

Here is a link with some updates regarding near-term SpaceX launch prospects

spaceflightnow article

Points of interest:
Next scheduled flight is a Turkmenistan satcom on March 21, but once again the kinetic requirements preclude carrying the recovery equipment.

The next launch likely to attempt recovery is the next Dragon supply flight to ISS, tentatively set for about April 10.

mikey
mikey
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RE: Here is a link with

Quote:

Here is a link with some updates regarding near-term SpaceX launch prospects

spaceflightnow article

Points of interest:
Next scheduled flight is a Turkmenistan satcom on March 21, but once again the kinetic requirements preclude carrying the recovery equipment.

The next launch likely to attempt recovery is the next Dragon supply flight to ISS, tentatively set for about April 10.

I wish they would test the feasibility of 'disposal' of the old stuff by sending it on a one way trip into the Sun, as opposed to returning it towards earth to burn up on re-entry or to land for us to then have to dispose or recycle it. A 'simple' very small booster should get it on the right path and then let the Suns gravity do the rest. I think the path is the critical calculation though, you wouldn't want the 'trash' to make a pitstop on some other planet or comet instead.

archae86
archae86
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RE: A 'simple' very small

Quote:
A 'simple' very small booster should get it on the right path and then let the Suns gravity do the rest.

Not small at all unfortunately. The additional Delta V required to escape Earth orbit would be considerable, and the added Delta V beyond that to convert a nearly circular orbit at Earth's distance into one intersecting the sun would be very much more again.

Sometimes intuition and orbital mechanics don't mix very well.

David S
David S
Joined: 6 Dec 05
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RE: RE: A 'simple' very

Quote:
Quote:
A 'simple' very small booster should get it on the right path and then let the Suns gravity do the rest.

Not small at all unfortunately. The additional Delta V required to escape Earth orbit would be considerable, and the added Delta V beyond that to convert a nearly circular orbit at Earth's distance into one intersecting the sun would be very much more again.

Sometimes intuition and orbital mechanics don't mix very well.


Even with those problems, I'd like that as a method of disposing of nuclear waste... except for the much bigger problem of the small-but-still-too-high chance of the launcher blowing up and spreading the cargo all over a large chunk of the planet.

David

Miserable old git
Patiently waiting for the asteroid with my name on it.

mikey
mikey
Joined: 22 Jan 05
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Credit: 621,948,997
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RE: RE: A 'simple' very

Quote:
Quote:
A 'simple' very small booster should get it on the right path and then let the Suns gravity do the rest.

Not small at all unfortunately. The additional Delta V required to escape Earth orbit would be considerable, and the added Delta V beyond that to convert a nearly circular orbit at Earth's distance into one intersecting the sun would be very much more again.

Sometimes intuition and orbital mechanics don't mix very well.

So you are saying that to launch something from the ISS, for example, towards the Sun, and have it actually get there, would take a HUGE rocket motor? In case it wasn't clear I was thinking of once in Space just send it to the Sun, not from the Earth to the Sun. They already spent HUGE amounts of energy to get the whatever into orbit, but to send it out of that orbit and onto elsewhere in the Solar System can take ANOTHER huge amount of energy? I had no clue!!

mikey
mikey
Joined: 22 Jan 05
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Credit: 621,948,997
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RE: RE: RE: A 'simple'

Quote:
Quote:
Quote:
A 'simple' very small booster should get it on the right path and then let the Suns gravity do the rest.

Not small at all unfortunately. The additional Delta V required to escape Earth orbit would be considerable, and the added Delta V beyond that to convert a nearly circular orbit at Earth's distance into one intersecting the sun would be very much more again.

Sometimes intuition and orbital mechanics don't mix very well.


Even with those problems, I'd like that as a method of disposing of nuclear waste... except for the much bigger problem of the small-but-still-too-high chance of the launcher blowing up and spreading the cargo all over a large chunk of the planet.

The Earth is covered in nuclear material anyway, if they could spread what you are talking about over a large enough area, it wouldn't even be noticeable. UNLESS it happened a few thousand times! Dropping a tank of the stuff on someones home though could be a MAJOR problem!!

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