SpaceX Should Reach Orbit With Its Starship Mars Vehicle Next Year Believes Musk

Oct 16, 2020 20:51 EDT
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Speaking at the Mars Society's 23rd Annual Convention earlier today, SpaceX C.E.O. and Chief Engineer Elon Musk shared his thoughts on the company's Starship launch vehicle platform and Mars missions. Musk formed the company with the objective of establishing a city on the planet, and Starship is SpaceX's chosen vehicle for this purpose.

At the convention, Mr. Musk shared important details about Starship's test flight schedule, the vehicle's design process and goals and when SpaceX might deliver a Starship NASA lunar lander prototype.

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SpaceX CEO Hopes Starship Will Reach Orbit Next Year But Not With Its Full Complement of Engines

SpaceX's current launch vehicle lineup, the Falcon 9, has demonstrated the key capability of reusability, of which Musk has always been a strong proponent. Reusability was also on the SpaceX CEO's mind today as he highlighted Starship's key design objectives. Through reusing its Falcon 9 rockets, the company has created a regular launch cadence and brought down costs.

However, even though SpaceX's current rockets are capable of launching and re-landing multiple times, they won't be sufficient at overcoming key problems of mass that engineers have to account for when sending payloads to Low Earth Orbit (LEO) and beyond.

When questioned by Dr. Robert Zubrin (President, Mars Society), who hosted the interview, about key design objectives of Starship and the differences between it and the Falcon lineup, the executive highlighted the importance of shipping large payloads to LEO and Mars, the relationship between them and the design advantages of a larger design.

The variant of SpaceX's Falcon Heavy heavy-lift launch vehicle generates roughly 5.5 million pounds of thrust through its first stage. The first stage of SpaceX's Starship launch vehicle which is the center of its Mars mission is capable of generating 16 million pounds of thrust via its 'Super Heavy' first launch stage. SpaceX/Twitter

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According to him:

“You first have to say what is the goal. And once you have what is the goal you can then measure various designs against that goal. Otherwise, you're seeing how are you evaluating why is one design better than the other? What is the goal? So the goal is get enough tonnage to Mars, and enough people to make Mars self-sustaining as quickly as possible. So then you say. Okay, let’s back up the math on this. We’re gonna need, gonna need a lot of tonnage, maybe I don’t know, a 100,000 tons, maybe a million tons. So you can’t be flapping around with these expendable rockets. They’re a joke. They’re absurd. Even the Saturn V is tiny potatoes.

We need..because if you wanna get a first-order approximation of a million tons to the surface of Mars, inclusive of people, you know that means probably something around four or five million useful tons into Low Earth Orbit. You know for every ton you get to Low Earth Orbit you get four or five tons. Hopefully close to five. Its…you know this math it really just starts squeezing like tiny percentages. Let's say confidently if you get five tons to low earth orbit, you get one million tons to Mars.That's...that’s confident. Maybe you can get, maybe all you need [is] four.

Anyway the point is you need five million tons into Low Earth Orbit to get one million tons to Mars. Now, let’s put this into perspective. Total global capacity to orbit, of all expendable rockets, is around five or six hundred tons I think. And if you said okay the world’s going to end if you do not increase your capacity, perhaps it could do a thousand tons.

. . . .For big rockets, you also get gauge advantages. So this is really in the nuances of rocket design and manufacturing here. So if things are really small, it’s difficult to get your gauge right. So basically how thick is the material? Like if you want to do castings, for example, there’s a minimum gauge of thickness for casting. There is a minimum kind of error bar on the…on this..on the materials skins. Even for composite rocket, you start hitting granularity issues. As you get bigger, you are no longer gauge limited. And you can get....your percentage accuracy on the thickness of walls and castings can be very good. These are nuances that almost no one appreciates. But suffice to say there are advantages to size. And you can certainly see this in many walks of life, if you’ve got a truck that’s carrying cargo it’s better to have a semi-truck and not a bunch of little trucks.”

Inside the Falcon's eye. SpaceX's Falcon 9 booster (three of which make up the Falcon Heavy) consists of nine Merlin 1D+ RP-1 rocket engines capable of delivering up to 221,000 lbf of thrust at vacuum and 192,000 lbf of thrust at sea level. (Image Credit: SpaceX)

He then proceeded to explain why Methane is important for Starship, as opposed to Kerosene which SpaceX currently uses with Liquid Oxygen to power the Falcon 9's Merlin engines. in the astronautic launch industry. According to Musk:

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“Within its architecture the Falcon 9 is close to a local maximum. If you say gas generator cycle kerosene oxygen vehicle of this particular size with a 12 foot or 3.6 meter diameter. Which is that size for road transport limitations, if you’re bigger than that you can’t transport on the road and your logistics costs become extreme. So, but having a long thin rocket is not very mass efficient. You end up having to have thicker skins to take out the bending moment. And having Kerosene is not the right fuel. Methane is a much better fuel. You can get higher Isp, specific impulse, basically efficiency. I don’t think a lot of us listening know what the rocket equation is, but in simple terms it’s actually very simple. So like a rocket is going to go further if the gas…if it shoots the gas out of the end faster and if a bigger percentage of its mass is propellant. I mean this is obvious [laughs] So that’s what the rocket equation says. So shoot out the gas faster in the right direction and increase the propellant…the percentage of propellant that’s going to get you to go future. With Methane, you can shoot out faster [laughs]”

SpaceX Hopes To Conduct High Volume Flights With Starship In 2022, And Conduct Testing With Fewer Engines

Dr. Zubrin then moved to ask Musk on when he believes SpaceX will be able to get Starship to high-altitudes such as the Stratosphere, to orbit and even to Mars. At this front, the CEO replied by stressing the difficulty of testing a vehicle like Starship, his estimates for testing, a regular launch cadence and the importance of the vehicle's Raptor engines.

Musk stated that:

“Alright. We’re obviously venturing into new territory, so it’s not like I have all these secret dates and I you know just keeping them from people [laughs]. So these are just guesses obviously. I’m pretty……I’m eighty to ninety percent confident that we will reach orbit with Starship next year. I probably….50% to 60%..50% confident that we’ll be able to bring the ship and booster back. That’s more of a dicey situation, we’ll probably lose a few ships before we get the atmospheric return and landing right. Might lose, hopefully, we don’t lose any booster cause that’s a lot of engines. Our initial booster flights will just have maybe two to four engines.

Not 28 engines. [laughs] 28 is a lot of engines. I think we’ll probably be doing high volume flights I think probably in 2022. So a couple of years from now. I’m trying to make sure that our rate of innovation increases, doesn’t decrease. This is really essential. In fact, if we don’t see something close to an exponential improvement in our rate of innovation, we will not reach Mars. Pure linear doesn’t get there. Well, I’ll be dead anyway if it’s pure linear. If it’s exponential we could get to Mars, we could probably send an uncrewed mission there in maybe four years. There’s a Mars conjunction every 26 months, there was one this year so this means in a couple of years there’s another one. Four years from now there’s another one. I think we got a fighting chance of making that second Mars transfer window.”

A render of SpaceX's Starship moon lander showing its final form. The lunar variants might not incorporate forward flaps and differ from other Starship upper stage variants. (Image: SpaceX)

Starship Prototype for NASA's Lunar Lander Will Be Ready In "Two Or Three Years" States Musk

SpaceX's Starship launch platform consists of the first stage Super Heavy booster and an upper stage Starship spacecraft. The latter has been selected by NASA as part of the agency's efforts to develop a vehicle for landing on the lunar surface. This design hinges on SpaceX's capability to refuel Starship after it has exited Earth's orbit, and the company won funding from NASA earlier this week for testing this refueling system. In its proposal to NASA, SpaceX also highlighted its plans to launch this upper stage with its Falcon Heavy heavy-lift launch vehicle.

When questioned by James Burk, Director of Information Technology for the Mars Society on when SpaceX could conduct orbital refueling with Starship, Musk replied that he expected this to take place in 2022.

In response to Burk's follow-up question that asked for a timeline for NASA's Human Landing System prototype for the Starship lunar lander, the executive stated that the prototype should be ready in two or three years, with the speed of development for orbital refueling determining the amount of tonnage that can be sent to the Moon; with this tonnage further determining the "significance" of the missions. 

SpaceX is currently testing early-stage prototypes of Starship at its facilities in Boca Chica, Texas. The company is expected to conduct a medium-altitude hop of a prototype soon, with the hop using three Raptor engines for the first time. These hops will provide the company with key data for Starship's propulsion system, with the vehicle featuring several design changes over the Falcon 9 due to using different propellants. The company is also currently investigating engine problems with the Falcon 9's propulsion systems as it waits to launch NASA astronauts and GPS satellites to their orbits.

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