The thread for space cadets!

[hobbsyoyo]

Flotation is not the same as zero gravity. You still feel gravity when you are buoyant, so that concern doesn't go away. I'm not sure if they have done gestation studies in space on mammals. Yeah, cesareans are a thing but my specific concern is that they might grow too large before they are actually viable. And that's putting aside birth defects that may pop up as a side effect of zero-g or low-g gestation. And we can both think of very simple scenarios of how this will play out but reality tends to be much messier than you or I can predict.

 

[Thorgalaeg]

True, reality usually is much messier than we can even imagine. Because that reason the ones going to mars shouldn't pretend to be too exigent about quality of life there. They should go with the same spirit as old colonist who arrived to America or Australia. There will be sacrifices and drawbacks, even death, but eventually...

Except vikings in Greenland

 

[hobbsyoyo]

True, reality usually is much messier than we can even imagine. Because that reason the ones going to mars shouldn't pretend to be too exigent about quality of life there. They should go with the same spirit as old colonist who arrived to America or Australia. There will be sacrifices and drawbacks, even death, but eventually...

Except vikings in Greenland

True story. It's my life goal to go to Mars and I definitely do not have rose-tinted glasses about it. Life is going to suck.

 

[hobbsyoyo]

NASA is going to launch a probe to examine the Sun this year and they are offering the public a chance to add their name to a microchip that will fly on board.

Here's the link:
http://parkersolarprobe.jhuapl.edu/The-Mission/Name-to-Sun/

 

[warpus]

The only danger of this strategy would be competitors building smaller and cheaper rockets that still can carry about everything customers want to send to space (and are also able to saturate the market). But I don't think that is going to be the case in the near future.

If this ever happens it seems spaceX would have to bring back a smaller rocket to compete with them. But maybe the cost efficiency of the BFR is going to be hard to overcome at a smaller size, even in 15-30 years?

Also the ability to land back on the launch mounts

I've read about this but not the details. When they're landing are they going to have to rotate the landing core precisely so that it lands in a very specific orientation? Or will any orientation work, as long as they land at the exact needed spot?

 

[red_elk]

It would be interesting to know if cells needs gravity to know the direction they must grow to.

They must grow outwards

 

[uppi]

Flotation is not the same as zero gravity. You still feel gravity when you are buoyant, so that concern doesn't go away.

No, you don't. If you are perfectly buoyant, the force on you is exactly zero and you cannot feel any force. Your body cannot feel that one force is gravity and the other buoyancy and just feels nothing. This is a serious problem for divers, which cannot feel which way is up and which is down and have to rely on external references. That means, embryos are already growing in a microgravity environment and I don't see how the mother being in a low-g environment should matter for the embryo (the mother might have problems, though, if the womb grows into places it is not supposed to). That doesn't mean everything is fine, because the fetus loses its buoyancy in the third trimester and lack of gravity might then lead to complications. But it isn't far to viability then, so they might make it to birth with only some problems. Or maybe all births need to be early births.

 

[Thorgalaeg]

They must grow outwards

Martian:

 

[hobbsyoyo]

If this ever happens it seems spaceX would have to bring back a smaller rocket to compete with them. But maybe the cost efficiency of the BFR is going to be hard to overcome at a smaller size, even in 15-30 years?

They already had a smaller rocket in this class, the Falcon 1. They retired it after just 5 launches (2 successful) and have been clear that they will not be reintroducing it. It doesn't align with company goals which are much further range than simply to make as much money as possible.

The thing about the rideshare market is that the launch service providers still have to spend a lot of time working on very low-cost add ons to their main missions. And sometimes those add-ons pose big problems for the main satellites which makes them even more difficult to accomodate. So SpaceX just decided that market wasn't worth chasing full force. They don't dissallow rideshares but I don't think they go soliciting them. Other providers (the Russians and Indians) are much more accomodating and have won the lion's share of those launches. And really once the dedicated small launchers begin launching regularly, I think they will offer prices that even BFR will have trouble competing with - especially when you consider the enhanced services that dedicated launchers can offer over rideshares.

The BFR will still be the cheapest option per pound by a mile but there's going to be a floor I think where they just can't go below for an individual ride share due to the effort that goes into processing each and every rideshare for launch.

I've read about this but not the details. When they're landing are they going to have to rotate the landing core precisely so that it lands in a very specific orientation? Or will any orientation work, as long as they land at the exact needed spot?

This won't be an issue. All modern rockets have roll control and can therefore change their heading after launch. American rockets in particular have a 'roll program' which is where the rocket almost immediately begins orienting itself to clear pad infrastructure in case of disaster and then orient itself correctly for ascent.

The Soyuz actually lacked this capability for decades which required the launch mounts to swivel to face the rocket in the correct direction but part of the upgrades they made to it to make it compatible with the launch site in Kourou gave it this capability.

Edit: Oh I misread your question. I thought you were asking if the landing orientation will matter for subsequent launches.

I have no idea if the core will have to rotate in a specific orientation for landing. I strongly suspect it would have to land in a specific orientation to interface with the launch mounts. It may have some sort of self-correction mechanism to force it to the correct orientation though (think rifling in a gun barrel).

 

[r16]

people , where have you been ? People are selling condos on Mars with the premise that inhabitants will be 3 meters tall and it should be interesting in bed ...

 

[Timsup2nothin]

They must grow outwards

Depends on the cell. Plants use differential rates and directional growth to turn leaf surfaces towards the sun.

 

[warpus]

Somebody posted this as evidence that the BFR will have to be refuelled 5 times on a mission to Mars, and then once to get back

Maybe somebody can make sense of this math? In the above spreadsheet there is also a link to this, they are supposed to be calculations that also include math for the landing (and maybe some other changes?)

Seems crazy to me to have 5 refuellings on a mission like this. I thought there was just supposed to be one. But I also read that this was going to be all really cheap, so.. that works I guess! But can somebody confirm that this is actually what's going to be happening?

 

[hobbsyoyo]

Neither of those are annotated enough for me to analyze in less than an hour. The second link seems to show that the BFS can have enough fuel to go the full way with just a single refuel though. And I think the assumption is that the BFS will be refueled on Mars through in-situ fuel production with however much it needs to go back.

If the BFS does take 5 refuelings to get to Mars then the whole idea is untenable in my opinion for practical concerns.

 

[warpus]

That's what I thought.

I admit my post wasn't super coherent, and neither are the spreadsheets. I guess we'll know more in a couple years when the BFRs are actually being refuelled and flying missions

 

[warpus]

I found this thing that IMO deserves its own post

I only watched the presentation by Paul Wooster (he's the principal Mars Development Engineer at SpaceX). Very interesting BFR information and visuals.

 

[Berzerker]

dont know if this was mentioned but the Kelly identical twins aint so identical any more, the one who just got back from a lengthy stay in space has a ~7% difference

I'm assuming they compared them before the trip

 

[uppi]

dont know if this was mentioned but the Kelly identical twins aint so identical any more, the one who just got back from a lengthy stay in space has a ~7% difference

I'm assuming they compared them before the trip

Fortunately, the media got that completely wrong. A 7% difference would most likely kill him quickly.

What actually happened is that a tiny fraction of his genes changed their expression in space. Of these, 93% turned back to normal as soon as he came back to earth. 7% didn't, but not 7% of his genes, but 7% of the tiny fraction that changed.

 

[Michkov]

Which is another case of an oveblown headline and terrible science reporting. Seems to get worse with each year.

https://arstechnica.com/science/201...ing-has-spawned-some-horrific-press-coverage/

 

[Cutlass]

Apparently this is real.

 

[hobbsyoyo]

Here's a cool video of the Falcon Heavy Center Core crashing into the water:

Fortunately, the media got that completely wrong. A 7% difference would most likely kill him quickly.

What actually happened is that a tiny fraction of his genes changed their expression in space. Of these, 93% turned back to normal as soon as he came back to earth. 7% didn't, but not 7% of his genes, but 7% of the tiny fraction that changed.

Which is another case of an oveblown headline and terrible science reporting. Seems to get worse with each year.

https://arstechnica.com/science/201...ing-has-spawned-some-horrific-press-coverage/

What never ceases to amaze me is how frequently science journalists covering space get basic facts wrong. I don't even mean the more esoteric aspects about space travel - it's very, very common for them to get basic things wrong like which country launched which mission and such - things they could very easily fact check with 10 seconds on google or wikipedia. And when it comes to anything technical they are usually hopelessly wrong.