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In January, we had an exclusive interview with Elon Musk, in which he explained for the first time his thinking – and the complex technical issues – behind his decision to build the SpaceX rocket and its stainless steel thruster. The previous design of the rocket (known at the time as the BFR) advocated carbon fiber, but Musk recalculated and used steel because of its durability, cost-effectiveness and ductility .
In the rest of this interview, Musk explains in detail what needs to be done to actually travel beyond the orbit and into space. In addition, it seems that Mars will have a beautiful park.
Ryan D'Agostino: What most potential future space tourists do not understand about the convenience of traveling in space?
Elon Musk: Some basic concepts of orbit and gravity are counterintuitive because they are not what we live. For example, many people think that if you go high enough, gravity stops. This is not true. The gravitational reach of the Earth is infinite. You could be on the other side of the universe. If you have enough time, if you do not have relative speed in relation to the Earth, you return immediately to Earth.
The simple Newtonian formula for gravity is GMM on R squared – you know, gravitational constant multiplied by two masses divided by distance to centroids. So if you have to travel 100 miles, you will not change the distance between you and the center of the Earth much. The attraction of gravity would seem the same to you. The reason we call this thing called zero gravity or microgravity – it's really due to the very fast zoom around the Earth. A rocket does not climb directly. He makes this bow. It goes only briefly vertically then turns and accelerates horizontally to the surface of the Earth.
The reason it is horizontal is that it is trying to further accelerate its radial acceleration. Its acceleration to the outside. If you swing a ball on a string – like a ball – you can make it essentially horizontal by rotating it very fast. This radial acceleration towards the outside is what maintains it. So you try to make sure that the radial acceleration to the outside is equal to the acceleration towards the inside of the gravity. So you have zero net acceleration, and that sounds like weightlessness. But in reality, you are like a support ball.
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Another way of thinking is like a ball in a funnel. Gravity looks like a funnel in the space-time. And if you spin a ball around this funnel, it will roll in the center. Even though the funnel is really big. That's what gravity looks like. At first, it will go into orbit very slowly in the center of the funnel, then accelerate in turns per second, as we get closer, then in the middle it goes very quickly, ok? That's the gravity.
So you have to turn the ball. That's what you need to do with a rocket.
RD: So, what are the implications for re-entry – or entry to Mars?
EM: The entrance is difficult. Sure. It is super hot. These things add up when you think about it. Like, why is the entrance so fast? It's because you arrive at a very high speed. You have to slow down the speed.
The minimum speed required to remain in low Earth orbit is approximately 25 times the speed of sound once you get there. You usually rub about 5 Mach to get there, [meaning] you need an ideal speed of about 30 Mach to put you into orbit so as to reach 25 and experience the weightlessness, by turning around the Earth. In low Earth orbit, you will zoom around the Earth every 90 minutes.
What really surprises many people is that you tell them that the International Space Station, which looks like a rather big unsightly structure, travels the Earth at 17,000 km / h. It completes an orbit every 90 minutes.
It's very fast.
Tristan Bassingthwaighte
RD: Let's talk about Mars. You must have spent time thinking about those first minutes, hours, and days.
EM: On Mars?
RD: On Mars.
EM: Ahh, not really. I mean – not the granularity of the minutes.
RD: Is it because the current focus is a lot on achieving this goal?
EM: Yeah yeah, you have to get there. It's a big problem. I think Starship will also be useful for creating a base on the moon. We will probably have a base on the moon before going to Mars.
RD: Could you simulate an Alpha from the base of Mars on the moon?
EM: It would be a little different because the gravity on the moon is much less strong and the moon has an atmosphere. But once you get there, it's totally manageable. It's not hard – there's a lot of work to be done once you get there, but it's not like, oh my god, we're on Mars!
There will be that from a fear point of view. But if you get there and you're alive, the hard part is accomplished. This is the difficult part.
RD: But planning will have consisted of knowing what you will do when you get there: food, water, fuel.
EM: Once you get there, these things are relatively simple.
RD: food. What is the plan?
EM: I mean, the easy way to make food would be to just hydroponically grow. You basically have solar energy – unsoiled solar panels on the ground, which feed the hydroponic underground, underground or protected by wires, earth. So you can be sure you do not have to worry about excessive ultraviolet radiation, a solar storm, or anything like that. Really pretty simple. You can simply use the hydroponics of the Earth. The hydroponics of the land will work well.
To have an outdoor and fun atmosphere, you will probably want to have a faceted glass dome, with a park, to be able to walk around without a suit. Finally, if you terraform the planet, you can walk without a suit. But for the next 100 years or more, you'll need a giant glass dome under pressure.
RD: You seem unimpressed by the people who say you can not terraform Mars.
EM: Of course, you can terraform Mars. Why would they think you can not? You can totally.
RD: And to make the fuel once on Mars, that does not pose you a problem?
EM: Well, it's a tricky technical problem, especially with regard to the energy required: you need a lot of solar panels or a nuclear power plant. Then, if you have a methane-oxygen system, that's what we're talking about, because the Mars atmosphere is mostly composed of CO.2, and there is a huge amount of ice water, so you have CO2 and H2O, from which you can make CH4 and O2– it's a simple Lego. You have three types of blocks. That's all. C, H and O.
Technical challenges: energy production and a good way to get ice. There is ice in the ground, but it's dirty. And it's not necessarily all ice-shaped. Sometimes it's like permafrost or something like that. If you could land somewhere near a glacier, where there is little land in the ice, it would be very useful. So, you have to extract ice, basically. You have an engineering challenge in the area of ice extraction and power generation engineering. These are your problems. On Mars.
The logical thing to do is to equip one of the ships with a propulsion plant proper and land it on the planet as a well functioning plant. And then, you just need little minor droids to get the ice cream and bring it back and deploy the solar panels.
RD: What do you hope to learn from the InSight Lander? Do you have people here who are watching what NASA has discovered? [Long pause.]
EM: We are certainly attentive to any new discovery concerning Mars. Yeah. But I want to say that Mars is pretty well understood. You know, it would be helpful to have more specific details on high concentrations of water ice. The higher concentrations of water ice you can find, the less your minor droids will have to work, and the less you need to heat the ground, evaporate water and get rid of what is not water. So, have high purity ice? Very useful. Less energy to heat it.
Nevertheless, one of the most difficult things to explain to people is orbit or space. Access to the space is easy. Entering orbit is difficult. It's 100 times more difficult to get into orbit than to get to what you call, in quotation marks, "space". It is, say, the Karman line at 100 kilometers, which is an arbitrary point where the atmosphere is relatively thin. This is usually called space. It's arbitrary. Obviously, it would be a coincidence if space started 100 kilometers away. I think it was random [named that] So the X-15 pilots could get astronaut wings in the 50s or something. You can not orbit a satellite 100 kilometers because the atmosphere is still too thick.
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RD: Is this one of the things you want to communicate the most to people? Orbit against space.
EM: Yeah. And if you want to go into orbit and return from orbit into orbit, it's now much more difficult than traveling 100 kilometers and turning around. It's not easy to go 100 kilometers and fall, but if you go 100 kilometers and you fall, you do not even burn the paint. But if you come into orbit, unless you have a heat shield, you will vaporize. D & # 39; right? Meteors arrive all the time, but they are usually sprayed or pulverized into tiny pieces before touching the ground, which is fine. You do not want to be the meteor.
You need something that allows you to reach the ground intact.
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