totm nov 2023 SpaceX Discussion Thread

[tater]

Possible.

[Bill Phil]

8 hours ago, cubinator said:

For me, Mars is important not just on its own as a destination but as a gateway to the rest of the solar system. If we can develop two-way transport between Earth and Mars, we'll be able to go anyplace in the solar system and stay there. And once we do that we'll be well on our way to building interstellar ships. That's why colonization of Mars is a big deal.

Mars isn't that much of a gateway - it's one of many possible destinations.

Earth orbit is more of a gateway than any other location. From there both Venus and Mars aren't far in terms of delta-v. And there's actually quite a lot we can do as a civilization in just the Earth-Moon system. Indeed the thermodynamics of civilization may necessitate activities that are quite interesting in this "region" of the solar system. And if beamed propulsion or even just advanced nuclear propulsion is developed and the required energy infrastructure with it then transportation in the solar system becomes easier (in a relative sense since we will be a more energy rich society - hopefully).

Interstellar vehicles are... difficult. We're talking immense energies (for both low mass high velocity vehicles and high mass low velocity vehicles, the scaling relationship isn't very nice). 

I really feel that colonization of Mars will ultimately be a footnote. Orbital habitats just have so much more to offer an energy rich society than any planet. It'll happen eventually, but I doubt it'll be a major event. Rather it'll be a long process that coincides with other efforts but brings less benefits.

8 hours ago, tater said:

The ability to use the solar system is another matter. I get that, and support it, but I would need to see a case for the economics of it that isn't fantasy.

Economics may never work out for space settlement. However thermodynamics will eventually rear its ugly head if our energy use grows (and since standard of living correlates quite well to energy use per capita I would argue it should grow, but with less damaging sources). Eventually our civilization may overload Earth's heat rejection capacity. Before that ever happens I would argue that we should be a space-based civilization - with major industries no longer on the planet and perhaps even major populations as well. This is because if we want to stay on the planet and remain a high energy society we will need to invent some way to increase Earth's heat rejection capacity - it's not impossible but it seems even less economically sound than expansion into space. That is to say that methods for launching large volumes of mass into space (and at survivable accelerations) are much easier to develop than a massive thermal control system for the entire planet. 

Of course civilization may collapse long before it ever threatens to overload Earth's heat rejection capacity.

Essentially it may be more costly to remain on Earth than to expand into space - a few centuries or maybe even millennia from now.

On a more SpaceX related note:

Hope Crew Dragon turns out well. Would be awesome to have more manned vehicles up.

[Guest]

10 minutes ago, Bill Phil said:

I really feel that colonization of Mars will ultimately be a footnote.

 O_o.... does not compute

[tater]

3 minutes ago, Dale Christopher said:

 O_o.... does not compute

All human environments off Earth in the solar system are 100% built. Seems to me stations make more sense (O'Neill colonies).

[Brotoro]

Have they said if they are going to send a destruct command to the booster, before or after abort? Are they going to command thrust termination before or after the abort? Or have they not shared a detailed flight plan?

[Guest]

3 minutes ago, tater said:

All human environments off Earth in the solar system are 100% built. Seems to me stations make more sense (O'Neill colonies).

ok, i'll go to mars you start building a space city. best of luck 

 

[Bill Phil]

Just now, Dale Christopher said:

 O_o.... does not compute

What does Mars really offer us?

Some more land area?

No, it's completely uninhabitable - without our intervention. If we're going to do that though then we'll get so much more bang for our buck by building artificial habitats that rotate to provide artificial gravity (plus you get access to a full 1g of gravity). 

A simple calculation using the mass of the Asteroid belt shows that we can build over 700 times the land area of Earth from just that mass. Mars is a drop in the bucket in comparison.

Obviously such a large endeavor will take an immense amount of time and effort but Mars just doesn't offer that much and suffers the same issues as Earth in addition to low gravity and less area - not much habitable area (all of which will be artificial). And since all artificial habitats (no matter the location) will be artificial, orbit is just easier.

Another thing to consider is relative difficulty - the largest object in Earth orbit is the ISS at over 400 tonnes. Meanwhile the largest object on Mars is around 1 tonne. Now this may change with Starship but no matter what happens Starship will also vastly reduce the costs for Earth orbit as well as Mars and the Moon - assuming everything goes perfectly. This means that larger objects in Earth orbit will be possible. It also means a lunar infrastructure could be done somewhat easier. This ends up making orbital habitats around Earth an even more likely prospect, especially since the technology can be somewhat related to orbital hotels - if such an industry ever comes to fruition.

Recently Al Globus found that the radiation environment in equatorial LEO is fairly mild due to avoiding the South Atlantic Anomaly (where radiation spikes). 

If we wanted to compare the costs and difficulty of putting a settlement of equal size into either location then it will be much easier to put it into ELEO than on Mars, and this only becomes more true with the introduction of Starship. Not to mention the advantages of being close to Earth - emergencies are easier to deal with, people can return to Earth, maybe visit relatives, and so on (provided Starship can actually make space access cheap enough). 

2 minutes ago, Dale Christopher said:

ok, i'll go to mars you start building a space city. best of luck 

 

I've said before that the ISS is the second most habitable place in the solar system - and even then it's a very far second to Earth. I'd take a space city over Mars any day.

At least then I have a better chance of coming back to Earth if things go awry.

[Guest]

dudes... im not trying to discourage whatever you think is cool. if you like the idea of orbital cities great. I like the idea of bringing life and civilization to mars, but I'm not going to have a discussion about which is better on the eve of the SpaceX abort test... it's too much like an us vs them debate about the aspirations of SpaceX vs BlueO. We can do both \o/, it's weird that it's a one or the other issue...

24 minutes ago, Brotoro said:

Have they said if they are going to send a destruct command to the booster, before or after abort? Are they going to command thrust termination before or after the abort? 

D: I hope not!

Edited January 18, 2020 by Guest

[tater]

One issue remains to be seen Re: Colonizing Mars. Is 0.38g compatible with human wellbeing and child development?

If the answer is no, Mars is a non-starter. We know at least that we can make orbital stations arbitrarily close to 1g.

Heck, put one in a low martian orbit (get the ~50% radiation mitigate for free). At least martian surface to LMO is an SSTO thing, so travel is easy.

[mikegarrison]

If we could build a planet's worth of orbital habitats, we could probably also terraform whole planets pretty easily. Both ideas are so far away from our current capabilities that they make no sense right now.

Economically, under the current conditions, it is really not possible to justify anything other than living on Earth. People don't want to go to space or go to Mars because it makes sense economically. They want to do it for the same reason they climb mountains and sail around the world solo and jump off cliffs with wingsuits. They want to do it to find out if they can, and because life is an adventure.

[Bill Phil]

35 minutes ago, Dale Christopher said:

dudes... im not trying to discourage whatever you think is cool. if you like the idea of orbital cities great. I like the idea of bringing life and civilization to mars, but I'm not going to have a discussion about which is better on the eve of the SpaceX abort test... it's too much like an us vs them debate about the aspirations of SpaceX vs BlueO. We can do both \o/, it's weird that it's a one or the other issue...

It's not about how cool it is (it is cool in my mind though). It's about how important Mars will be in the solar system. 

Settling Mars is certainly cool and has a romantic allure (especially since a number of old sci-fi books are set on Mars). 

This isn't the place to have that discussion anyways. It just seems to me that Starship is more likely to lead to orbital habitats than Mars settlement - and even then both are not likely to happen.

Space settlement is very hard to do. So difficult that we literally do not have the technology. We likely have the science and most of the understanding to do it, but not the technology. And developing that technology may take the better part of this century. Or longer. 

Maybe we'll get lucky and the technology will be developed relatively soon, but I doubt it. 

In the interim we should be developing an industrial capacity in space - allowing construction of large objects and efficient transportation around the Earth-Moon system. Hopefully both Starship and whatever BO does will help with this.

15 minutes ago, mikegarrison said:

If we could build a planet's worth of orbital habitats, we could probably also terraform whole planets pretty easily. Both ideas are so far away from our current capabilities that they make no sense right now.

Not quite.

Terraforming Mars for example requires massive amounts of oxygen and nitrogen (more per square meter than Earth due to the lower gravity) and likely massive reprocessing of the soil. Imagine doing that for 150 million square kilometers!

For a comparable area of space habitats you can have less oxygen and nitrogen per square meter and it is much easier to landscape. 

Essentially you're comparing making one giant thing with millions of smaller things - eventually you may see amortization with the difficulties and costs for making the smaller things. Indeed in the best case scenario you can also build the equivalent area faster - if a habitat has 100 square kilometers and is capable of building another in ten years (and we also expand the resource acquisition to support this manufacturing) then one habitat will result in the equivalent area of Mars in a few centuries whereas terraforming Mars may require over a thousand years and even then people may require breathing masks to go outside. But then here's the thing - the space settlements don't have to stop there. Another few doubling periods and you've already built more area than Mars can provide.

Of course a 10 year doubling period is quite optimistic, but the point stands - building a planet's worth of orbital habitats is likely easier to do than terraforming planets. Plus you can build even more area.

Terraforming Mars piecemeal may be possible and may be done but there's a gravity issue and you only get 1 Mars worth of area out of it in the end.

Yes both concepts are beyond current needs to an extreme. But the orbital habitat concept has more room to expand and can be built anywhere in the solar system, if the materials are provided. Plus it can be used to settle any star system so long as it has asteroids or other easily accessible matter sources.

Also the required mass for building an equivalent area to Mars with orbital habitats would represent about 4.1E-5 times the Moon's mass. Dismantling the Moon could enable us to build 20 thousand times Mars's current land area (which is roughly equal to Earth's land area). Of course that's a bad idea (for Earth's ecosystems) and would require a massive infrastructure, but we could build an equivalent area to Mars without having to do much beyond Earth's gravity well (you'd need to probably grab asteroids to get enough nitrogen and water among other volatiles - but there's plenty of oxygen on the Moon at least). 

Edited January 18, 2020 by Bill Phil

[kerbiloid]

Just to bring both subtopics together.

Spoiler

 

Edited January 18, 2020 by kerbiloid

[mikegarrison]

Look, you're talking about *dismantling the moon*! And then you think bringing some water to Mars is too hard to do?

Obviously, building an orbital hab is easier than terraforming an entire planet, but I still say that building a planet's worth of orbital habs is not so obviously easier than terraforming a planet. And of course there are the possible intermediate steps of building habs on a planet. If you can build a city-sized orbital hab, you can certainly build a city-sized Mars hab.

We know there are no resources available in empty space except sunlight. We know that Mars at least has mineral resources.

Again, none of this really makes sense right now. There is nothing in space or on Mars that we really need. Or at least, there is nothing YET on Mars or in space that we really need YET.

I will also say that quite likely our most urgent need for terraforming is going to end up being on the planet we currently live on. We're already engaged in an unplanned terraunforming experiment.

[AVaughan]

2 hours ago, Dale Christopher said:

what if S2 takes the brunt of the shock and blows apart freeing the weight from the top and then the booster proceeds to perform a soft splashdown using only thrust vectoring 

Then you have a hazard to shipping that SpaceX will need to cleanup.

[tater]

24 minutes ago, mikegarrison said:

Look, you're talking about *dismantling the moon*! And then you think bringing some water to Mars is too hard to do?

Obviously, building an orbital hab is easier than terraforming an entire planet, but I still say that building a planet's worth of orbital habs is not so obviously easier than terraforming a planet. And of course there are the possible intermediate steps of building habs on a planet. If you can build a city-sized orbital hab, you can certainly build a city-sized Mars hab.

We know there are no resources available in empty space except sunlight. We know that Mars at least has mineral resources.

Again, none of this really makes sense right now. There is nothing in space or on Mars that we really need. Or at least, there is nothing YET on Mars or in space that we really need YET.

I will also say that quite likely our most urgent need for terraforming is going to end up being on the planet we currently live on. We're already engaged in an unplanned terraunforming experiment.

I don't think any of it is happening soon, but with Elon tweeting about 100k people heading to Mars at a time... I have a little room in this thread to suggest that moving a few small asteroids to the Eart-Moon system and mining them, and building some sort of hab is easier. Actually, though, the hard bit for any large hab might well be where does the nitrogen come from... Might be an issue on Mars as well. Happily we'll only be off topic on SpaceX Mars plans for a few hours, then in flight abort!

 

 

 

[magnemoe]

5 hours ago, Brotoro said:

Have they said if they are going to send a destruct command to the booster, before or after abort? Are they going to command thrust termination before or after the abort? Or have they not shared a detailed flight plan?

As I understand no self destruct command unless needed, they will cut the engines but assume this is standard for any abort. 
I think that the aerodynamic pressure on upper stage is likely to rip it the top apart, this will give asymmetric drag who will give shear forces  

[MinimumSky5]

Yeah, given what this booster is about to go through, high explosives do seem a little redundant when it comes to destruction.

[Guest]

Hmm, seems like test has been delayed?

[kerbiloid]

Spoiler

  

5 hours ago, tater said:

100k people heading to Mars at a time

1. Are they going to name the first Starship Hameln?

2. How much does a healthy human colonist cost on the Barsoom Martian market?

 

[MinimumSky5]

 

 

[Teilnehmer]

When launching a crew, will the launch be postponed in a case of rough sees somewhere among all possible areas of emergency splashdown?

[Guest]

2 minutes ago, Teilnehmer said:

When launching a crew, will the launch be postponed in a case of rough sees somewhere among all possible areas of emergency splashdown?

I get what you are saying but at the same time speaking about this test specifically, they are going to have teams of people standing by out there and having to work in those conditions. It can be very dangerous in high seas.

[Wjolcz]

13 minutes ago, Teilnehmer said:

When launching a crew, will the launch be postponed in a case of rough sees somewhere among all possible areas of emergency splashdown?

If seas are rough during the launch then weather is probably not much better. Since the rocket isn't going all the way up there they probably don't care about atmospheric conditions that much. They would if crew was involved.

[kerbiloid]

They must hurry up, if they are really going to build three dragons per day and send the colonists to the Mars .
Otherwise how can they build the million people city by 2050.

https://translate.google.com/translate?hl=ru&sl=ru&tl=en&u=https://www.rbc.ru/technology_and_media/19/01/2020/5e23e77c9a7947f70aa3a847

P.S.
Can't get why Mars and dragons, when starships.

Edited January 19, 2020 by kerbiloid

[Treveli]

4 hours ago, kerbiloid said:

They must hurry up, if they are really going to build three dragons per day and send the colonists to the Mars .
Otherwise how can they build the million people city by 2050.

https://translate.google.com/translate?hl=ru&sl=ru&tl=en&u=https://www.rbc.ru/technology_and_media/19/01/2020/5e23e77c9a7947f70aa3a847

P.S.
Can't get why Mars and dragons, when starships.

Pretty sure that's a mistranslation, Starships not Dragons, and launch not build.