Exploring Mars

kbd512 · 2021-06-15 10:10:32

Louis,

I seem to recall that the Space Shuttle was sold to the public the same way, but the STS Program never came close to achieving the theoretical cost reductions it would enable. Will SpaceX succeed where NASA failed? I guess time will tell.

SpaceNut · 2021-06-15 19:31:39

Slow repetition rate, higher tile lose, need for workers to be kept on doing nothing ect add up

louis · 2021-06-15 19:46:02

In my view there is no doubt the concept is sound - in a way the Falcon 9H for instance never was and never will be (that was a sad detour for Space X). It seems to me Space X have everything right on the Starship. The only issue is do they have the engineering skills to get it to work reliably. Judging by previous performance, the answer has to be yes.

kbd512 wrote:

Louis,
I seem to recall that the Space Shuttle was sold to the public the same way, but the STS Program never came close to achieving the theoretical cost reductions it would enable. Will SpaceX succeed where NASA failed? I guess time will tell.

kbd512 · 2021-06-16 08:55:08

Louis,

Starship is a good concept if it works as intended. If it doesn't, then it's just another rocket with a novel propulsion technology.

tahanson43206 · 2021-06-16 09:40:35

For kbd512 re #54

The exchanges between you and Calliban (on one hand) and Louis (on the other) are building up a remarkable collection of posts for the forum readers who (I hope) are included in the 60+ spammers who are constantly knocking at the door of the forum.

For the sake of those readers, and NOT in any way a criticism, please expand upon the part of your post #54 ... "novel propulsion technology".

I had NOT been thinking of Starship as in any way novel, but (no doubt) I missed one or more significant advances.

It looks to me (as a lay observer) as though Starship is a natural evolution of Falcon 9.

(th)

kbd512 · 2021-06-16 11:12:31

tahanson43206,

It was widely believed at the time that the combination of LOX/LH2-fueled RS-25s from Aerojet-Rocketdyne and APCP-fueled solid rocket boosters from Thiokol (now Orbital ATK) to provide a 1.5 stage-to-orbit (RS-25 provide thrust from launch-to-orbit, solid rocket boosters provide 80%+ of the liftoff thrust for initial acceleration from the launch pad and then run out of fuel and separate a few minutes after lift-off while the RS-25s continue providing thrust all the way to Low Earth Orbit / LEO) transport solution would revolutionize space travel by reducing costs through reusability of the Space Shuttle orbiter (part of the vehicle that goes to orbit and carries humans and/or cargo) and Solid Rocket Boosters / SRBs. SSTOs (Single-Stage-To-Orbit) type vehicles (all feasible examples being LOX/LH2-fueled) were heavily experimented with, but ultimately proved to be wildly impractical in actual operations, which is why there aren't any at the scale of a human-rated launch vehicle carrying significant tonnage to LEO. While the refurbishment of the orbiter's reusable heat shield proved to be the most costly and time consuming aspect of the entire system (in terms of total cost over its operational lifetime, since the vehicle basically had to be "re-qualified" for space flight after each mission), every aspect of the solution was far more expensive than initially envisioned, partly due to maintenance practices and partly due to the immaturity of the technology since this was the very first attempt at reusability for an operational space launch vehicle. The demands that the military placed upon the orbiter's cross-range to do 1-orbit polar military satellite insertions certainly complicated the design, but it was the single most complex vehicle ever designed when it became operational, period. I think it holds that distinction to this day.

Large solid rockets can provide staggering amounts of thrust, which is absolutely necessary for lift-off / first stage booster applications, but they're difficult to control, most can't be throttled except through internal propellant surface area modification (geometry of the propellant grain that's actively burning after ignition), and if the seals ever fail, then the vehicle will explode, which is tantamount to a death sentence for everybody aboard. That unfortunate circumstance ultimately claimed the lives of the Space Shuttle Challenger crew in 1986. Unfortunately, reuse of solid rockets is minimal / complex / expensive, they're not particularly cheap or easy to fabricate to begin with (extreme levels of process control and deft handling prior to use are required), and while density impulse (total thrust provided for a given volume of propellant) is fantastic compared to practical (not so toxic you need to wear a chemical suit to use them) and common (low cost and widely available) liquid propellants (LOX/RP1, LOX/LH2, LOX/LCH4; there are others, but these are the most practical / cheap / performant / non-toxic, and the only ones to power super heavy lift rockets, meaning rockets that can sling the weight of a main battle tank into orbit), the specific impulse is too low for anything but a booster or a rocket with 3 to 5 stages to reach orbit (to a point, less is more when it comes to stages, since each successive staging event adds a lot of complexity and opportunities for various failures).

The RS-25, while it achieved bleeding edge specific impulse performance using a practical liquid bi-propellant combination (LOX/LH2), which was absolutely necessary for an engine used from lift-off to orbit, was so expensive and complex, in order to make it both performant and reusable (early models pretty much trashed the expensive blade assemblies in the turbopumps with every flight), that it was (and is) impractical in terms of cost. Each RS-25 is a $75M engine, meaning each engine has the price tag of a complete heavy lift rocket, high routine maintenance requirements, and the overall performance of a Ferrari, hence the nickname it received, "the Ferrari of rocket engines". The recent upgrades to use modern computer control and new manufacturing techniques have helped to reduce the marginal cost of producing each new RS-25, but the engine remains very expensive, very maintenance-intensive, and very complex to operate. It does have the distinct advantage of a very lengthy and successful service career (no in-flight catastrophic failures). In short, it's proven to work well, but the price paid for that to happen makes it unaffordable to non-governmental users.

There's no great "magic" in SpaceX's LOX/LCH4-fueled Raptor engines. It makes some aspects of the propulsion solution easier to control and more flexible than solid rockets to be sure, whereas other aspects are not-so-great. The rocket's propellant tanks will still suffer from propellant boil-off without active cryogenic cooling technology, the propellants themselves are functionally equivalent to LOX/RP-1 in many ways so specific impulse (fuel economy for rockets) is rather pedestrian in nature, meaning more than 95% of whatever is "delivered" anywhere is still going to be propellant thrown out the back of the rocket, rather than useful cargo, and the overall handling of the propellant is little different than LOX/LH2. CH4 gas / vapor / boil-off is every bit as easy to ignite as H2 and still highly energetic, so propellant handling safety protocols remain virtually unchanged. In short, all the LOX/LH2 handling equipment for STS / SLS is needed for LOX/LCH4 for Starship.

Since the operating pressures produced by the turbopumps are even more extreme for Raptor than for the RS-25, overall service life is an unknown quantity. The difference is that Starship Super Heavy has a LOT more of these "extreme performance" engines than the Space Shuttle or Space Launch System (39 Raptors in total, versus 3 RS-25s for STS or 4 RS-25s for SLS), they have to withstand at least 4 significant firing events per mission prior to significant refurbishment in a properly outfitted facility back on Earth, and they have to be much cheaper than RS-25 due to the sheer numbers that SpaceX is planning to use, meaning at least 1 cargo Starship and 1 tanker Starship to support 1 flight to anywhere else in the solar system, and in all probability, there will be 2 or more tanker Starships for each cargo Starship to expedite refueling in LEO so that propellant boil-off is minimized. This is a very significant technological hurdle to clear. Overall, Starship Super Heavy is very much akin to the failed Soviet N1 lunar super heavy lift rocket that was a competitor to Saturn V, but with the added complication of full reusability, and hopefully with much better manufacturing process control and adherence to flight safety protocols.

To be fair to Starship and to Louis' point, Starship is a good basic design for a super heavy lift rocket (two-stage-to-orbit, same as Saturn V, at least the variant of Saturn V that carried the Skylab space station to LEO) that uses low-cost heat-resistant stainless steels in its construction to reduce the need for elaborate / expensive / complex heat shielding to protect Aluminum or Carbon Fiber composites, and Starship has had the benefit of 50+ years of rocket engine and launch vehicle development that N1 didn't benefit from. However, whether or not Starship ever achieves the cost reductions necessary for interplanetary colonization remains to be seen. Historically, Super Heavy Lift Launch Vehicles (SHLLV) like Saturn V / N1 / STS / Energia / SLS have never been cheap or easy to develop and operate. Will Starship Super Heavy finally "crack the code", so to speak, by providing a cheap and reliable SHLLV? That remains to be seen. There's still a ton of development work to complete.

kbd512 · 2021-06-16 11:39:17

tahanson43206,

Since I seem to have not addressed the primary question in my last post, the only part of Starship's propulsion solution that is somewhat "novel" in nature, is the use of LCH4 as the fuel and a full-flow staged combustion engine. A plethora of experiments / engine development programs using LCH4 fuel were conducted bay various space agencies over the decades, but they kept using RP1 instead of LCH4, because the perceived benefits of Methane over highly refined Kerosene were not seen as significant enough to warrant a switch to a cryogenic fuel, in addition to the cryogenic oxidizer (LOX) that they were already using.

To wit, Liquid Methane / LCH4 allows for autogenous pressurization the way LH2 does, meaning no need to use very high pressure tanks of Helium or Nitrogen gas to force-feed the cryogenic liquid fuel into the inlet pipes that supplies the fuel to the rocket engines, CH4 doesn't coke the inside of the engine with Carbon fouling / residue because the hydrocarbon chain of CH4 is as short as it can get, so it won't polymerize inside the engine the way Kerosene / RP1 will when both fuels are subjected to extreme heat and pressure during combustion processes, and CH4 the simplest / easiest hydrocarbon fuel to make / synthesize from scratch using CO2 and H2O, via the Sabatier reaction / process, thus it can be made on Mars (or any other planet with CO2 and H2O) since Mars has an abundance of both of those natural resources (this says nothing about how easy they are to extract or how much energy is required to do so, only that there's no shortage of the raw materials).

Edit:
There's one last consideration that puts a check mark next to LCH4 as a viable rocket fuel, and that is cost. Methane is very cheap to extract from the Earth and incredibly abundant here on Earth, and also on other planets in the Solar System. We simply don't know if there's Methane underground on Mars, but there could be. If there was Methane under the surface, then we would drill oil wells and pump it out of the ground if it didn't naturally rise to the surface on its own, because that is the lowest energy cost way of producing fuel (for rockets or anything else that needs power).

Similarly, the use of steel for building rockets is all about cost. Steel is the cheapest / strongest stuff you can get that can survive high heat environments (hypersonic launches and reentries), it's incredibly durable, it's very easy to recycle, and you probably can't find a planetary body that doesn't contain some quantity of Iron ores and Carbon. How practical it is to extract is a different question. Both Aluminum and Carbon Fiber require far more energy input per unit weight of raw material produced, they're typically more labor intensive to fabricate parts with, if easier to work with in some other respects, and lighter for a given strength part that needs to be fabricated, but very finnicky to assure mechanical properties for, as compared to Iron-based alloys, and far more difficult to evaluate in terms of service or fatigue life (although there are viable methods for doing so).

In short, SpaceX made good basic design choices and I'm not questioning that, but whether or not the totality of what they've designed and built becomes part of a viable interplanetary colonization program is an open question.

Last edited by kbd512 (2021-06-16 12:07:05)

kbd512 · 2021-06-16 15:12:42

tahanson43206,

One last point that must be made is that even if Starship achieves revolutionary cost reductions through mass manufacturing and increased flight rates, if the demand from paying customers doesn't materialize, then there's only so many of these Starships that SpaceX can afford to build and operate without outside support. Despite the fact that the Space Shuttle was cheaper on a per-launch basis than Saturn V, there wasn't an explosion in the demand for launch services from paying customers. Other launch vehicles such as Ariane, Atlas V, Soyuz, etc, were cheaper still, but the demand for launch services remained tied to government, weather, and commercial communications satellites, with a smattering of science missions funded by the national space agencies. Obviously drastically reduced launch costs are a very good thing for space commercialization and colonization, but it will take some time for people who design the payloads to "catch up", so to speak.

If you have a rocket that can deliver 150t to LEO, but there's no actual payloads that require that capability, then at most you can cannibalize most of the commercial space market with your revolutionary new low cost launcher, but then what?

Let's say you charge $20/kg, which would be an extraordinary / revolutionary feat of engineering. SpaceX can probably launch every other commercial satellite in the build pipeline using 2 or 3 flights per year. Well... That was the entire market, so where is the revenue stream coming from next?

They can potentially get space agencies to pay them to clean up all the orbiting space junk, so all that's left is a modern / current fleet of more durable satellites that get serviced on-orbit because now it's cost-effective to do that, so periodic replacements of relatively lightweight components are made, but this is basically a once-per-decade activity.

So, Starship has covered a network of completely modern satellites for communications and weather, space junk removal, we build a deep-space network of communications / positioning satellites for future science missions, we replace the aging ISS with a new station, we have a Lunar Space Station, and we have a Mars Space Station. From there on out, corporate or governmental sponsorship to construct moon and Mars bases will be required. Apart from building bases, all the rest of that stuff is a "Year One" set of activities, with periodic maintenance or replenishment thereafter. We're going to need an unmitigated expansion of science activities from universities and governments, and corporate sponsorship from there on out, if we're to sustain that kind of momentum in space exploration and colonization. The bargain basement launch services are good for that purpose, but very few corporations and governments have the cash to support colonization, because we're talking about 6+ flights of Starship to go anywhere else, and then our launch costs start to look like those associated with expendable rockets, which means deep-pocket investors only.

Science missions are still going to dominate the budgets of government space agencies, because that's the reason for their existence. The big Mars rovers were $5B programs, but only $300M or so of that was the ride on the rocket. Now the ride will be "noise" in the program budget, so the hardware development and testing costs will continue to dominate. People with enough nickels to rub together could feasibly put up the cash to send private robots to explore other celestial objects of interest to a special interest group. If one wealthy project sponsor put up the funds for a launch, then a team of dedicated but unpaid university students could use materials and resources provided by their university to produce lower-cost science missions, but the engines and specialty chips will have to be supplied by people with very deep pockets.

In the same way that the military has a practical test at the end of your schooling, aerospace engineers could feasibly be "tested" by having them build and operate their own scientific exploration satellite or rover, which is a good thing, but that means using heavier but lower cost materials like steel instead of exotic alloys or Carbon Fiber.

In short, there's a serious pipeline issue for space exploration projects that requires a build-out (that will take many years to accomplish) to take advantage of this new rocket technology that makes launch costs a footnote in the project's expenses ledger, else this program falls on its face, not through any fault of the launch vehicle at all, but because nobody is building the payloads necessary to use the new rocket to its potential. SLS is experiencing this type of problem right now, albeit because it's so expensive rather than so cheap. There's a literal handful of science missions where the expense of using the rocket can be justified.

Calliban · 2021-06-16 16:07:49

Kbd512, well done for an excellent post that raises an issue that has seldom been considered on this board, but is probably going to be the single biggest obstacle that Musk is going to face. He is essentially building a transportation company, hoping that enough customers will appear when the costs are low enough. But even if he can run Starship launches for $2million a shot, there is institutional inertia and psychological inertia to overcome. And it is unfortunate that Starship will reach maturity during what is now certain to be the most severe and protracted economic contraction in Earth history. Musk may end up being a victim of bad timing.

When I first joined this board, I was interested in the prospects of asteroid mining, targeting near Earth asteroids, specifically. My reasons for doing so, were: (1) These objects enjoy abundant solar energy (for at least some of their orbit); (2) They are low gravity environments, making takeoff and landing quite easy; (3) At least some of them contain volatile organic materials and water; (4) Many of them are rich in industrially important metals. One final advantage: they can be reached efficiently using low thrust, high ISP propulsion, all the way from LEO. If I were interested in space colonisation on a budget, these objects are still the most promising targets in my opinion. Colonisation can be staged, using low thrust, high-ISP tugs, to deliver the required equipment to the target body incrementally. Whilst it is possible to return high value materials to Earth, I suspect that the exports of such a colony will be bound for Earth orbit. They will include things like large telescopes, solar power satellites and hopefully, the hulls for large scale colonisation ships, as envisaged by Robert. As fascinating as Mars is, the NEOs are more accessible to commercial groups on tight budgets.

Last edited by Calliban (2021-06-16 16:17:03)

louis · 2021-06-16 17:16:46

Thanks for that walk-through kbd.

Re the marketability of Starship, it has a head start because Space X intend to use it for Starlink (which most analysts seem to think will be hugely profitable) and for the Mars colonisation project*. Space X also think it can be used for ISS supply though NASA and the Russians may have other views - the idea of such a monster approaching the ISS may make them nervous.

If Starship works technically then it is going to be cheap, so it probably will corner a large part of the satellite launch market (especially if it's as dependable as the Falcon 9).

I am a bit more sceptical of E2E transport rivalling airlines, but I think it will be used on a few select routes.

* Obviously a lot of people can't see how Space X could make any money from that whereas I think - if we set aside the sunk development costs for Starship - there will be huge profits from the get-go.

kbd512 · 2021-06-16 17:39:20

Calliban,

It's a more intractable problem than psychology, which is malleable to a degree, it's technological in nature. The major aerospace manufacturing corporations are the only ones who actually design and support space-related hardware because they've traditionally been the only ones who could afford to do it. They're accustomed to using a specific set of exotic lightweight metal alloys and composites that their customers would then likely balk at, on grounds of total cost. If transport suddenly became a minor cost driver, then they'd have to start figuring out how to take advantage of that fact by designing more robust hardware from cheaper metal alloys.

We can already see how the widespread commercialization of "small sat" technology has decreased the cost of these miniature vehicles by specifying the use of commodity hardware in lieu of aerospace specialty hardware. There may be certain cases where weight is a factor, but nobody who is sending a university satellite experiment to LEO would splurge on an Aluminum-Lithium alloy if it was ten times more expensive to source and machine than a marginally heavier 6061 Aluminum or low carbon steel chassis. At $20/kg, for a 100kg steel chassis mini-sat, even if that Al-2195 chassis saved 20kg in weight, it still wouldn't be worth the added expense and hassle to source and machine it, because most machine shops are going to turn you away or charge a fortune if you show up with some new metal that they've never machined before. In reality, we're probably talking about using a lot more 6061 or 7075 and skipping all of the exotic Lithium / Magnesium / Beryllium alloys, but the days of "big spending" on exotic aerospace materials and machining methods are likely coming to an end. It's going to become all about lowest cost design that can survive for "X" amount of time, or in other words, "planned obsolescence". StarLink is designed this way, incidentally.

This is a good problem to have, but it's going to take years for everyone else to figure out how to best use much lower transport costs by adjusting the hardware designs accordingly. It won't make any sense to build a cargo module from Aluminum if it's 5 times the cost after machining is taken into consideration, but only half as expensive to launch as steel, and customers won't go for it. That's just an example, though, as I'm sure we'll be using lots of Aluminum for many decades to come, and for good reason. However, the "thought process" of the designers must now transition from "lowest weight possible" to "lowest total cost" or "ultimate durability", dependent upon use case, because eventually a lack of durability will begin to drive cost in a world where space launches are only four times more expensive than a 747 flight.

tahanson43206 · 2021-06-16 17:53:03

For kbd512 re entire series ....

Thanks for your thorough coverage of the topic over multiple posts.

I was happy to see appreciation from Calliban and Louis, and expect others will be adding support as they come online.

This post is reserved for a tag for entire series, if I can think of one (or two or three).

Todo: Add search term for kbd512 series

(th)

Calliban · 2021-06-17 02:19:53

$2million per launch for a 100te payload, puts space travel within reach of private citizen groups and machinists building stuff in garages! If raises a lot of possibilities that I think people will take time to get their heads around. When we talk about space travel on this board, there has always been the assumption that the missions will be carried out by governments or billionaire businessmen.

kbd512 · 2021-06-17 04:57:05

Calliban,

Yes, that's the big and small of it. We're going to have to rework our model for space hardware fabrication so we don't wind up with needlessly expensive satellites and habitat modules and whatnot, that were only made so to begin with by insanely high launch costs. After the launch costs are addressed, the hardware costs are next on the list. We need mass-manufactured rad-hard chips for science missions, commercial SDRs and lasers for communications, mass manufactured solar panels and ion engines for good fuel economy, etc. That's going to take some time to work out, which is why we need to start now, so that this new launch system doesn't face plant the moment its ready to use, for lack of demand.

Mars_B4_Moon · 2022-08-16 07:24:05

NASA’s new Sample Recovery Helicopters will make flying on Mars less ‘boring’

https://www.popsci.com/science/mars-sam … licopters/

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#51 2021-06-15 10:10:32

Re: Exploring Mars

#52 2021-06-15 19:31:39

Re: Exploring Mars

#53 2021-06-15 19:46:02

Re: Exploring Mars

#54 2021-06-16 08:55:08

Re: Exploring Mars

#55 2021-06-16 09:40:35

Re: Exploring Mars

#56 2021-06-16 11:12:31

Re: Exploring Mars

#57 2021-06-16 11:39:17

Re: Exploring Mars

#58 2021-06-16 15:12:42

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#59 2021-06-16 16:07:49

Re: Exploring Mars

#60 2021-06-16 17:16:46

Re: Exploring Mars

#61 2021-06-16 17:39:20

Re: Exploring Mars

#62 2021-06-16 17:53:03

Re: Exploring Mars

#63 2021-06-17 02:19:53

Re: Exploring Mars

#64 2021-06-17 04:57:05

Re: Exploring Mars

#65 2022-08-16 07:24:05

Re: Exploring Mars

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