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“What If: Starship

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From the translator : Thought of doing a translation of "continuation" posts about SLS SLS: what now? But in the process I realized that Casey is too much into politics, who is who in NASA and what is their relationship with the President and Congress – all sorts of specific American government agencies stuff, not particularly interesting to habrabs.But there is one very interesting idea, so I will give it here: the fragment about "Starship"

For example, today (March 4, 2021) SpaceX successfully landed a prototype "Starship" in Texas. SpaceX has the talent and resources to allow them to expand spaceflight capabilities step by step; they continue to broadcast their very clear intentions, and act as if they really intend to succeed.

I have asked around among my colleagues, but I have never been able to find any commission at any level or center of NASA that would study the implications of putting the "Starship" into service. At this point there is no 100% certainty that SpaceX will pull it off, but it would be worthwhile to have some sort of back-up, otherwise most of the public statements from senior management, officially forced to sing hosannas to " SLS " seem to exist in some separate universe where even " Falcon 9 " has never yet landed.

It shouldn’t be too hard to find a hungry scientist who salivates profusely at the thought of sending a 100-ton station to, say, Saturn. The positive aspects are pretty obvious. But what about the downside? What is NASA to do with teams that cost several billion dollars a year to maintain, and whose main specialty is building rockets and space stations, whose entire architectural philosophy is already at risk at today’s launch costs, not to mention potentially improving by an order of magnitude?

Mars Rover " Perseverance " cost us $2.4 billion – that’s several thousand salaries over nearly a decade. Thousands of people worked on this rover because landing on Mars is incredibly complex, and the weight of components must be calibrated to the nearest tenth of a gram on a system weighing a ton. It’s all carefully hand-assembled from chips, circuit boards, titanium tubes, motors, cameras and other imposing components, often of special acceptance. And then suddenly "Starship" can bring in 100 of these in a single flight, and now what? What is NASA to do with a team that can design one ultralight Mars rover in ten years and a billion dollars when demand has jumped a thousandfold and marginal cost has fallen that much? Build an assembly line? Figure out how to assemble them with a team of ten people? Build one every couple of weeks?

In short, in a world where the sluggish failure of "SLS" is excused and/or ignored while "Starship" is going full steam ahead to revolutionize the industry, NASA should think very carefully about its place regarding manned missions that might be happening without agency involvement.

From the translator : And here is where NASA, built on the mold of the 60’s, with a planning horizon of several decades, finds itself in a near singularity situation: the landscape may change beyond recognition in some 5-10 years. The "Falcon 9" first successfully landed in 2015, just 6 years ago, and today landings are commonplace (at least at SpaceX), and it surprises me more when a rocket (wow!) misses past a barge dangling on the waves. And here, to gauge the extent of this singularity, I would like to cite another of Casey’s posts, With lunar mission calculations With a regularly flown "Starship" with refueling in orbit.

This post looks at how the "Starship" can be used to transport people and cargo to and from the Moon in various situations. It continues previous articles About "Starship" and "Artemis" and "Starship" as a deficit-free space transport Roughly speaking, by the end of the post, the reader should have a good idea of the available variables and benefits for various transportation scenarios using "Starship".

It’s worth noting right off the bat that "Starship" is In a special league among lunar landing modules As part of the program HLS NASA’s specification required the ability to deliver at least 9 tons, and ideally 12 tons, to the surface of the Moon. The "Starship" in its most basic configuration can deliver more than 200 tons. Someone here clearly stands out from the crowd.

But the real strength of the "Starship" is not its huge payload, but its cheapness of operation. The point of carrying 200 tons once when we can fly it several dozen times – and cheaper than other candidates?

"Starship" has tremendous payload capacity, but by refueling fuel and oxidizer at intermediate points along the route, we can reduce fuel costs for transporting fuel – the same principle that underlies multistage. That is, by increasing the complexity of organizing the fuel transfer process into deep space, more cargo can be carried per fuel unit. Is it worth it to do this? Let’s do the math.

My analysis uses numbers consistent with the Wikipedia article For March 2021 : tanks for 240 tons of methane and 960 tons of oxygen, dry weight 120 tons, payload capacity 100 tons per LEO, specific impulse in vacuum 380 s, thrust 12000 kN, cargo compartment volume 1100 m 3 When variations of these figures provide additional information, I will adjust these parameters; Δv will be calculated from the law of conservation of orbital energy.

Squeeze

In this post I analyze four different mission profiles :

  • Flight of a fixed payload (FF) (e.g. pressurised and habitable crew compartment) with low-Earth orbit (LEO) to the lunar surface and back to LEO.

  • Delivering cargo to the surface of the Moon with the ship returning to LEO empty.

  • Flight of an empty "Starship" to the surface of the Moon and return to LEO with as much cargo as possible (e.g., lunar regolith ).

  • Delivery of cargo to the surface of the Moon without the return of the "Starship" ("garbage" scenario).

For these four profiles, I analyze five progressively more complex fuel/oxidizer refueling schemes :

  • Refueling with a tanker on the NOO.

  • Bunkering at LEO and geotransition orbit (GPO).

  • Tanker refuelling at LEO, GPO and at low lunar orbit (UFO).

  • Transportation of fuel between LEOs, GPOs, and UFOs using an ionic traction tug with electricity from solar panels – "ionic tug" IB.

  • Using oxygen mined on the Moon to fuel the oxygen tank (this is 80% by weight of the fuel pair "Starship") – "lunar oxygen" LC.

For these 19 (LC does not make sense for "one-way") scenarios, I calculate the mass of cargo carried by one cargo ship; the number of auxiliary launches required, and the ratio "mass/launch" as the resulting quality indicator. The results are presented in the table below.

Refill

Crew Return

Cargo to the Moon

Cargo from the Moon

One-way load

NOO

25, 13, 1.9

57.5, 13, 4.4

43.5, 11, 3.35

216, 13, 16.5

GPO

200, 31, 6.5

539, 38, 14.2

326, 27, 12.1

753, 41, 18.4

ufo

670, 69, 9.7

1733, 96, 18.1

1092, 51, 21.4

1924, 101, 19.04

IB

670, 33, 20.3

1733, 59, 29.4

1092, 17, 64.2

1924, 62, 31.0 quickly
1924, 32, 60.1 slow

lc

1742, 63, 27.6

2263, 72, 31.4

2299, 11.5, 200

NN (tons), number of starts, NN/startup

As an integral measure of quality, though, "mass/launch" can be deceptive to the mission developer. For example, even though IS roughly doubles the "mass/launch" of a one-way flight, this figure does not take into account the cost of maintaining this complex infrastructure and building a new ship. Generally speaking, it seems that thanks to the heroic workers of Boca Chica and "Starships" and launches in general will be a minimal expense of the entire mission.

Oh, and it should also be noted that 200 tons of almost any cargo would take up more volume than is available from the "Starship" unless we put half the Olympic pool in there along with a couple of whales.

Refueling at LEO is more than enough for one-way launches and crewed flights. For comparison : "Shuttle" could deliver 25 tons to LEO, and a fully refueled "Starship" could deliver 25 tons from LEO to the surface of the moon and back to LEO, all without refueling. If it is very necessary to deliver 300 astronauts in one flight, a little refueling on the approach to the GPO would suffice.

The simplest case: refueling at LEO.

"What If: Starship
“Building bases on the moon, cheap, no bullshit"

No synchronization there with the complex halo orbit "Lunar Gateway" no tying launches to time windows, no planning decades in advance for incredibly expensive infrastructure in deep space. Just a ship built to solve a specific problem, with no compromises. An architecture that makes it possible to deploy a large lunar base with a budget comparable to A new (or so) Antarctic station NSF With a budget of $1 billion a year, NASA could launch such a mission (with slight variations) every 90 days – a huge step up from current access to space via the ISS.

From the translator : yes, yes, I foresee some comments of a kind "Arkady, what the hell are you writing here, what the hell are 100 tanker launches in a row ?-quot; but what the hell, what if ? Maybe not tomorrow, but in 5, 10, even 15 years – all the same: the moment a completely reusable cheap system that does not require complex maintenance between launches, all the current space program instantly becomes obsolete. What is the point of developing an expensive platform for satellites or stations on expensive "space" components for a long time? For the same money, you can make and launch 100 stations on consumer grade components with multiple redundancy, and whatever if the weight is greater.

There is still an open question with the second key component, orbital refueling. It seems to be not even experimented with yet, and it’s not a fact that it will be realized as Musk plans – through microgravity, but in any case, it’s a much simpler task than "fast reusability".

In general, I never tire of repeating myself: these are very interesting times we live in.

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