SpaceX - The Quest For Mars


#261

SpaceX to fly two space tourists on a week-long trip around the moon NEXT YEAR.

I presume one of them is TI?

space.com/35844-elon-musk-sp … today.html


#262

Was this always part of the plan? Sudden jump into space tourism seems a bit frivolous for SpaceX, although its probably good for cashflow?


#263

Yes, the falling launch cost makes things like this possible, this is what Musk wants

They are paying a price close to what people have payed for trips to the ISS and getting far more IMO, looks to me that we will see people on the Moon very soon

Also if Musk can pull this off with a bit of luck Trump will push for the SLS to be cancelled, and have NASA fund the ITS


#264

Only if I can get some sort of tax break to cover the cost!

@NorvilleBarnes was it always part of the plan? Yes and No.

Everything SpaceX does is about getting to Mars.

Crew dragon the human-rated version of their capsule is designed to deliver astronauts to the ISS and the development cost were covered by NASA. It has propulsive landing capability and so can land like the SpaceX rockets. So they plan a Red Dragon mission in 2020 to land a dragon capsule (without humans) on Mars, but they need more deep space experience. Many had speculated that they would send an empty capsule around the Moon but others said they wouldn’t to save on costs.
What Musk announced was classic SpaceX. Now they get the deep space mission experience and someone else covers the costs.

I’ll say it again, what Musk has done (and to a lesser extent Besos) is to make space exciting again.

It’s been 45 years since Appollo 8 orbited the moon. In my entire life, no men or women have been further away than low earth orbit. I can’t wait to see two non-professional astronauts do what the professional ones and their respective agencies failed to do for the last >40 yrs.


#265

First refly of rocket coming up …

bloomberg.com/news/articles/2017-03-24/spacex-launch-of-first-reused-rocket-to-mark-milestone-for-musk


#266

It’s very exciting, this will be the first time an orbital rocket that has been to space will be reflown. I’ve already got my popcorn.


#267

Well the shuttle was an orbital rocket that was regularly reflown, but its operation and refurbishment costs were so high that expendable rockets were cheaper. For spacex to succeed in its reusability goals, it has to ensure that these costs are kept low without affecting reliablity.


#268

They’re government funded. They’ll receive endless amounts of funds till they get it right.


#269

SpaceX, no, its a private company, funding for their work on making the Falcon 9 reuseable comes from re invested profits or from capital invested by the main share holders, this argument was done already in the Tesla thread, also they don’t need endless amounts of funds, it looks like they have most of it worked out, their main competitors are years behind them, and right now it only looks like Blue Origin are moving in the right direction


#270

They did it 8DD

The first launch then landing then relaunch and relanding of an orbital class booster rocket.

This dramatically reduces the cost of access to space.

I look forward to the day within my lifetime of the Ryanair turnaround model for rockets.


#271

If its a €19.99 flight to the Moon or Mars then I won’t mind one bit

The video below is from 2011, so it took a while for SpaceX to get to this point but they got there in the end, this is one of the things I like about Musk, each step of the way he tells the world and his competitors what his next move is, and each step of the way they don’t believe him, the longer it goes on the funnier it gets

I remember a few years ago reading about someone who got hired to work in PR for Musk/SpaceX, and he spent about six months trying to figure out what Musk’s angle was, what the hell was he up to ? what does all this Mars talk mean ? and then eventually the truth dawns on him, its not an angle, its not a scam, Musk really does want to go to Mars, the competitors and haters still don’t get it, long may it continue


#272

Cannot stop watching the landing vid … struts pop out five seconds before a flawless touchdown on a heaving barge. It’s mad!


#273

+1
that deserves a round of applause (muppets who clap upon Ryanair landing please take note :slight_smile:


#274

THAICOM 8 Launch from 27th May, 2016


#275

I know nothing about Rocketry but that landing is impressive. It looks like a scene from a Sci-fi film.


#276

One of the less reported but very cool thigs in this last mission was that also for the first time ever SpaceX recovered the fairing intact.

The fairing is the clamshell thing at the top of the rocket that encapsulates and protects the payload (satellite) on its way up. The Fairings until now have simply burnt up or smashed into the ocean. They are not cheap at about $6 million dollars a go. That’s not so much if like ULA you charge circa $250 million per launch but SpaceX charged $62 million for that last launch so at $6m a pop it now becomes an appreciable % of the launch costs.

SpaceX has been experimenting with fairing recovery but this was the first successful recovery. Basically the fairings now also have thrusters and an attitude control system. So after they are jettisoned, they steer themselves into an orientation for re-entry. As they are so light and have a large surface area they are already a good shape for reentry and for flying through the air. They are basically glided down and when slow enough a steerable parachute is deployed to gently land it in the ocean.

Recovery of the single engine 2nd stage is the only part of the rocket remaining to be recovered. That and a 24-hour turnaround are the next goals.


#277

It feels very sci fi because that’s how all the very old sci fi rockets landed. I love this pic, just look at the size of those legs! just goes to show how impressive it is to actually land this thing.


#278

Another one with (tiny) people for camparison:


#279

Why not use 3 legs ?

They lost a stage due to a leg failure already, so why is 4 better than 3


#280

I imagine it’s all about centre-of-gravity. The CoG must stay inside the base or the booster falls over.
Suppose this is the Falcon-9 booster and legs – the important aspects are to scale (1 cm = 2 m):

The arrow in each case shows how far the CoG would have to move for a tip over. I am using booster width = 3.66 m 1], and total leg span = “about 70 feet”, 21.34 m 2]. That makes the distance from body centre to leg tip = 10.67 m. We can get the lengths of the arrows by considering the two right-triangles with hypotenuse 10.67 m. In the four-leg case the angle between the leg tip and dotted line is 45°, whereas for three legs it’s 30°, so:

https://latex.codecogs.com/gif.latex?L_{arrow(4)}%3D\sin45\degree\times10.67\text{%20m}%3D7.54\text{%20m}
https://latex.codecogs.com/gif.latex?L_{arrow(3)}%3D\sin30\degree\times10.67\text{%20m}%3D5.33\text{%20m}

The tipping distance is nearly 50% greater for four legs. The angle that the booster would have to lean to make this happen depends on where the CoG is vertically. A poster here estimates that the engines are pretty heavy compared to the empty booster tanks, and puts the CoG at 14.9 m vertically. Note, he uses a smaller value for the leg span than SpaceX provided, and so gets a smaller angle of inclination.

Using my numbers the angle would be:

https://latex.codecogs.com/gif.latex?\theta_{(4)}%3D\tan^{-1}\left(\frac{7.54\text{%20m}}{14.9\text{%20m}}%20\right%20)%3D27\degree

Whereas for three legs this would be:

https://latex.codecogs.com/gif.latex?\theta_{(3)}%3D\tan^{-1}\left(\frac{5.33\text{%20m}}{14.9\text{%20m}}%20\right%20)%3D20\degree

Definitely a case of “four legs good, three legs bad”.