Exoscientist
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NASA is now opening up the Mars Sample Return mission to the commercial space approach. The usual NASA government financed approach is estimated to cost ~$10 Billion. But following the commercial space approach it probably could be done at literally 1/100th that at ~$100 million including launch cost.
I had estimated it as less than ~$200 million using the Falcon Heavy as launcher:
Low cost commercial Mars Sample Return.
http://exoscientist.blogspot.com/2023/07/low-cost-commercial-mars-sample-return.htmlThis could get ~750 kg back from Mars with the Falcon Heavy as the launcher. However, it probably could in fact be launched on the Falcon 9. The Falcon 9 can launch about a quarter of the mass of the Falcon Heavy to Mars, for all the in-space stages, so estimate the sample size returned from Mars of ca. 180kg.
At a $40 million launch cost of the reused F9, then all together with all the in-space stages, the mission cost probably could be less than than ~$100 million. Such a low mission cost probably could be paid for by advertising alone.
But to encourage participants to take up the task of such a fully privately financed mission, NASA could offer a prize of say $200 to $500 million to whoever could accomplish it, with some smaller incentive prizes to those who accomplish some key required steps.
Bob Clark
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32 minutes ago, SunlitZelkova said:
I’d be skeptical these can be called delays when Artemis has never had a realistic timeline to begin with. When it began, the first landing was scheduled for 2024- a purely political date.
Instead of reassessing a choosing a realistic goal, they have only been moving milestones back by a year at a time as new issues in development come to light.
Meanwhile, SLS has been delayed for years, as tater described.
According to the original plan, EM-1 (Artemis I) would be in 2016, and then EM-2 (Artemis II) would be in 2018.
I think a landing in 2025 or 2026 would have been achievable if Artemis had kicked off in 2017 or so. At that time NASA was still planning for the silly ARM mission.
Apollo the Moon landing program began in 1961 and landed in 1969. Roughly 8 years. Artemis began in 2019, so a better date would be 2027 or 2028 (the latter of which is Ars Technica’s predicted date).
An article on the Starship performance shortcomings for the Artemis missions:Starship Faces Performance Shortfall for Lunar Missions
by Alex Longo
https://www.americaspace.com/2024/04/20/starship-faces-performance-shortfall-for-lunar-missions/
Bob Clark -
6 hours ago, SunlitZelkova said:
Incorrect, IMO. SLS is the primary source of delays. Artemis I was originally scheduled for November 2021 but was pushed back by a year due to delays. We might have been closer to Artemis II if it weren't for the delays between the rocket's inception circa 2011 and the completion of the first vehicle in 2021.
I would bet $1000, that yes they were. It's well known NASA and SpaceX have had good communication with each other on HLS development progress.
There is no evidence they did this, but if they did, then I believe SpaceX would inform NASA.
Reading the article it’s clear the delay in the development in the Starship specifically in the refueling capability is a primary reason for why these alternative missions for Artemis III are being considered.“An unrealistic timeline
The space agency's date for Artemis II is optimistic but potentially feasible if NASA can resolve the Orion spacecraft's heat shield issues. A lunar landing in September 2026, however, seems completely unrealistic. The biggest stumbling blocks for Artemis III are the lack of a lander, which SpaceX is developing through its Starship program, and spacesuits for forays onto the lunar surface by Axiom Space. It is not clear when the lander or the suits, which NASA only began funding in the last two to three years, will be ready.”
Note the alternative missions being mentioned now for the Starship in Artemis III will require no refueling flights.
Bob Clark
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On 4/18/2024 at 5:36 PM, SunlitZelkova said:
Color me skeptical that jet engine maintenance can be translated to rocket engines. The stresses out on them in flight and the temperatures they operate at are completely different.
What is your basis for suggesting this?
I am also skeptical of this. Current Raptors that fly are not intended for reuse right now, so there would be no reason to run them at lower power.
The sea level Raptor 2 sea level thrust is 230 tons. For its vacuum thrust estimate it as proportionally higher by how much higher the vacuum Isp is over the sea level Isp: 230*(353/327) = 248 tons.
The Raptor Vacuum thrust is given as 258 tons. Then the total thrust for the 3 sea level Raptors and 3 vacuum Raptors should be 1,520 tons.
But the thrust for the ship of the current version is given as only 1,250 tons:
So it was started at 82% of full thrust. Commonly, you throttle down a rocket engine as most of the propellant burned off. The result is the overall average thrust was less than 75%.
Bob Clark
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14 hours ago, tater said:
It should not be lost sight of the fact the delays in Stasrship are a primary cause in these delays in the Artemis landing missions.Who in space reporting will put to NASA the tough questions:
Was NASA aware the current version of Starship could only get 40 to 50 tons to orbit, so they would have to wait for V2 or even V3 to do Artemis?
Did SpaceX inform them they throttled down the Raptor for reliability on IFT-2 and IFT-3?
Bob Clark
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A route to aircraft-like reusability for rocket engines.
https://exoscientist.blogspot.com/2024/04/a-route-to-aircraft-like-reusability.htmlAn interesting discussion on longevity of jet engines:
The question I raise is whether this could also increase the reuse capability of rocket engines.
Near the end I suggest, SpaceX is using this principle of running the engines at lowered power to increase engine life for the purpose of increasing the reliability of the Raptors. If they are, then they should explore the potential of this principle to also extend rocket engine reuse capability.
Bob Clark
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On 4/11/2024 at 1:28 PM, sevenperforce said:
Speculation -- most of it already rebutted many times -- from beginning to end.
As you know, Elon was talking about the dev version that was intentionally launched with underfilled tanks to a non-orbital trajectory.
His suggestion that this was still capable of 40-50 tonnes to orbit suggests that Starship dev is well on track to meet goals...goals that, I must add, do not depend on the performance of any dev version.
SpaceX has done zero qualification flights to date, as they are still in development of their launch vehicle. Since all qualification flights are in the future, there are no "further" qualification flights needed.
As an attorney with a particular certification in securities law, I can tell you that being "scrupulously forthright" is much more important for officers and board members of a corporation than it is for engineers (or whatever you imagine a "Chief Engineer" to be), and that your particular quibble over the way that static fires are described is nowhere near the ethical line for misrepresentations.
Where SpaceX deviates from industry standards, they do so openly and intentionally. You might as well complain that Apple deviated from industry standard by introducing an iPhone without a removable battery. Sure, people didn't like it, but it certainly didn't stop it from begin successful. Besides, you have presented no evidence that SpaceX has failed to share information with its potential customers about the duration and thrust levels of its static fires.
Those were items C11-C20, so not the top of the list. Additionally, your phrasing -- "tendency of the Raptor of..." -- does not reflect the FAA's corrective action statement. More importantly, all of these were corrected to the FAA's satisfaction.
Each of which have been debunked.
No.
So NASA and the FAA were fooled, then?
The trouble is if you run the numbers for the specifications SpaceX has cited for the SuperHeavy and Starship, i.e., their dry and propellant masses, and Raptor thrust and Isp, SH/SS should well be able to make 100+ tons to orbit as a reusable. I think NASA engineers were able to take the SpaceX proposal as a viable solution for an Artemis lander because their numbers checked out. But now we find the reusable payload for the current version is only 1/3rd the originally predicted 150 tons to orbit. What explains the drastically reduced payload capacity? This is a major issue because the current version can not perform the refueling functions of the Artemis lander missions at that low payload value.
My opinion: I think NASA was blind-sided by that low announced payload value. SpaceX and NASA will have to be open about what that severe loss in payload, by 100 tons, stems from.
Bob Clark
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SpaceX should withdraw its application for the Starship as an Artemis lunar lander, Page 3: Starship has radically reduced capability than promised.
https://exoscientist.blogspot.com/2024/04/spacex-should-withdraw-its-application.htmlRobert Clark
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On 4/6/2024 at 3:05 PM, tater said:
About 31 minutes in Elon suggests the current version V1 would be capable of 40 to 50 tons to orbit. This is bad because SpaceX sold NASA on the idea the Starship HLS could serve as an Artemis lander based on 150 tons to orbit reusable and “10ish” refueling flights. If the capability is max 50 tons, then it would take “30ish” refueling flights.
If they intend to use version V2 then this is bad because it would require further qualification flights for the larger version and more importantly further qualification of the more powerful Raptor 3 engine needed.
This last is doubly bad because I’d be willing to bet dollars to donuts that they never informed NASA that the current version couldn’t do it and further development would be required for the larger version.
Bob Clark
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36 minutes ago, CatastrophicFailure said:
And then there’s this:
The TL:DW:
I’d like to see them get some actual payload to orbit, even if it’s inert like water or liquid nitrogen.Bob Clark
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On 4/3/2024 at 6:16 AM, Superluminal Gremlin said:
IFT-1 - Big Damage. Required a complete re-think of all involved systems
IF2-2 - Moderate Damage to the Test Stand, much reduced everywhere else
IFT-3 - There was damage? (Sarcasm
). Mostly dents and dings. Am surprised there are no moves to build some protection for the tank farm, for example.
At its rate, by IFT-5? the damage will be low enough, and SpaceX well enough versed in the way of the 3 R's. (Reduce Damage, Reuse parts and Recycle what they can).
SpaceX has completely dismantled the second OLM, located at the Kennedy launch site:
Chris Bergin - NSF @NASASpaceflight
The final Orbital Launch Mount (OLM) leg at KSC 39A has been demolished ahead of a likely pad redesign prior to East Coast Starship launches.
https://twitter.com/NASASpaceflight/status/1775529100335108442Evidently, NASA or SpaceX or more likely both were unhappy with the level of damage on an OLM after a Starship launch.
They started dismantling it just one week after IFT-3. Rumor has it the new design will have a flame diverter.Bob Clark
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SpaceX Starship has a serious problem that no one is talking about!
https://www.youtube.com/watch?v=9SUbx3IkfRAHis argument is the pad damage after each flight might take a month or more to repair. That would extend the time for all the refueling flights for the Artemis missions to a year or more. But when you have cryogenic propellant stored in orbit that long it results in severe boiloff problems. That means additional refueling flights to replace the propellant lost to boiloff. But at a month or more between flights, that means even longer time in orbit for the propellant and additional boiloff, so even more refueling flights. The result is the number of refueling flights becomes impracticality large.
The answer might be you need a full flame diverter like used by Apollo to prevent pad damage. Gee, those Apollo guys really were smart.
Bob Clark
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3 hours ago, Superluminal Gremlin said:
I would like to interject with the fuel bars suggesting total fuel capacity for the mission (not the total design capabilities).
Multiple sources give a 3,400 ton propellant load for the booster and 1,200 tons for the ship, for 4,600 ton max propellant load. The 4,500 ton total given in the SpaceX tweet is only 2% off this value. That could be just round off error or it could be you don’t want literally the tanks to be filled to the very top to allow for boiloff of the cryogenic propellant.Bob Clark
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11 hours ago, sevenperforce said:
There was a 0% chance of Starship reaching true orbit because that was not the design trajectory. If Starship had reached true orbit, then something had to go very, very wrong. So obviously Elon was not talking about true orbit; he was saying that there was an 80% chance of Starship making it successfully through staging and the full-duration second-stage burn to its intended SECO.
Otherwise you're saying that when Elon says "80% chance" he is actually saying that the mission only has a 20% chance of success.
I've already painstakingly explained this to you. The very sentence where SpaceX says they had a "full propellant load" they also state the total amount of propellant and it is significantly lower than the actual full capability of Starship, meaning that it was a "full propellant load for this mission" not a "full propellant load for the maximum design capacity".
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Oddly, not just suggesting it could reach orbit before the mission, Elon said it did reach orbital velocity after the flight:
What max propellant load are you saying SH/SS could carry?
Bob Clark
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On 3/14/2024 at 2:07 PM, AckSed said:
All right, let's say Exoscientist's suspicions are justified, and the Raptors, even now, are prone to exploding. Presume they are also a pain to relight and require ullage and settling of the propellant before they'll behave.
Can you make a staged combustion engine more reliable? Peter Beck of Rocket Lab says you can: by building it to withstand and run at extremes, then under-driving it, you end up in the same level of reliability as a gas-generator rocket engine. Neutron's Archimedes is ox-rich, not full-flow, but building to run at max, then under-running at a more comfortable level is a solid path to good reliability.
Can they program Starship and/or Superheavy to under-run the engines at the cost of payload? I say yes.
Will they, or is Elon cowboying ahead with demands for, "More pressure! MORE thrust! More payload! Stuff blowing up! Boom!" and laughing maniacally? I don't have that insight, but they are complying with FAA regulations and NASA requirements, and I do believe Musky-boy knows when not to push his engineers and the physics to make things blow up, now the basic stack mostly works.
On relight: How many flight tests would it take to uncover all the quirks in handling the stack, and implement the necessary hardware and software changes to make relight reliable? We have at least four more planned, because that's how many boosters are being built right now. There are more on the way.
SpaceX has been using Falcon 9 Starlink launches to hone reuse parameters, learn more about the airframe and where its margins are e.g. jettisoning the fairings half a second earlier each flight. It's clear they intend to do the same with Starship/Superheavy. They will have at least four more attempts to relight engines in orbit and on landing, and test heatshields further.
Starships and Superheavies can and have been modified, or scrapped entirely, thanks to their stainless steel construction. The engines are the most expensive part and apparently problematic, but I have outlined a path to making them more reliable. If the engine design is fundamentally flawed and cannot relight at all without a forest of proper ullage thrusters they may have to add them. And that's fine. They will do that.
When I look at SpaceX and what they've achieved, I'm reminded of Parson Gotti, in the webcomic Erfworld: "We try things. Occasionally they even work."
Thanks for that. Do you have a link where Beck said this? I’ve suggested that SpaceX intentionally ran the Raptors on IFT-2 and IFT-3 at reduced power, i.e., thrust, to improve reliability.This has broader implications than just the Raptor question:
Can running a rocket engine at reduced thrust extend lifetimes?
Can someone in rocket propulsion answer if this fact about jet engines also holds for rocket engines?
If so, increasing a turbopump rocket engine power just 10% to 15% cuts engine life in half. And conversely, decreasing it by 10% to 15% doubles engine life. And would this still work if we repeated the concept multiple times? If we reduced the thrust by .9^5 = .60, i.e., to 60%, which most turbopump engines can manage, then we could increase the lifetime by a factor of 2^5 = 32 times? Then a Merlin engine with a lifetime of, say, 30 reuses by running it only 60% power could have its lifetime extended to 1,000 reuses?
Is this a known fact about turbopump rocket engines their lifetimes increase radically by a relatively small decrease in their thrust levels?
Bob Clark
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On 3/29/2024 at 1:46 PM, sevenperforce said:
Appreciated a short synopsis. There's no way I was listening to a whole big post.
With respect to the booster engine landing burn relight: once grid fin control was lost, the booster return was expected to be a failure. If you'll recall, the CRS-16 mission suffered a similar fate when one of its grid fins entered a hydraulic stall and stuck hard-over. There, the single engine tried valiantly to correct for the problem, but it was already off-nominal. This is the same situation. Engine relight depends on a number of factors, including vehicle stability, and so once you are spinning out of control you don't expect engine relight to work.
He has an obvious error at item 4 -- "orbital" velocity. There is no indication whatsoever that Starship failed to reach its intended velocity or trajectory.
He then says that the payload door demo was not successful because the vehicle started to spin once the payload bay vented to space. That doesn't make any sense. It's clear that Starship lost attitude authority (likely due to frozen propulsive vents); whether or not it lost attitude authority doesn't impact the success of the payload door demo. He subsequently says "we have no indication that the test took place" and claims that this is because we did not see any graphical change in the LOX levels, which is also nonsensical; there was no indication that the GUI was supposed to show this. This should be a questionmark, not a failure.
Finally, he claims that because the re-entry time was three minutes different from the estimate from some random person on the internet, this meant it did not re-enter where it was supposed to re-enter. I shouldn't have to explain how silly THAT is.
He has an obvious error at item 4 -- "orbital" velocity. There is no indication whatsoever that Starship failed to reach its intended velocity or trajectory.
That is a debatable point because Elon did say there was an 80% chance of the Starship reaching orbit on this flight:
But later SpaceX said they were planning a flight just under orbital velocity. So in that infographic from TonyBela.com it might be Bela was taking the reaching orbital velocity objective in item #4 from what Elon said.
But there still remains the question of why didn’t IFT-3 reach orbital velocity? In the case of IFT-2 they vented LOX reducing the velocity it was capable of, and Elon even said if they had a payload and had not vented LOX they would have reached orbit.
But they didn’t vent LOX on IFT-3 and SpaceX said they had a full propellant load and from the view of the propellant gauges the propellant was virtually expended in both stages. So why were they not able to reach orbit even though carrying 0 payload?
Bob Clark
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22 hours ago, magnemoe said:
The satellite constellations run pretty low power and its pointed downward. We are moving away from the large TV antennas and over to low power cellphone, wifi and low earth satellites so earth will be harder to detect. The thing you could see of starlink is the up-link stations. Now these signals are broad band compressed and encrypted so hard to differentiate from noise.
Thanks. I didn’t think of the uplinks. Even though it might not be possible to decrypt the signals, it might possible the spectrum is so unusual to be unlikely to be natural.Bob Clark
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Interesting article here about researchers who had for a moment thought they might have detected evidence of intelligent extraterrestrial signals:
However, it is notable in their search that they excluded radio frequencies commonly used for communications on Earth so as not to accidentally detect those signals. But if those frequencies are commonly selected for use on Earth they also may be commonly selected on extraterrestrial systems.
Then it is quite notable there are multiple plans worldwide for megaconstellations containing tens of thousands of satellites each. The question: how radio loud would the Earth be then when these tens of thousands of satellites are in place? How far away would the Earth be detectable then in radio frequencies from other systems? Would the Earth then have a peculiar radio spectrum that would be unlikely to be produced naturally?
Because of the intereference from the Earth communications we couldn’t reliably detect such signals from other systems using the radio observatories on Earth. But how about the lunar far side? Astronomers want to maintain the radio silence on the lunar far side for scientific research in the radio spectrum:
Astronomers call for radio silence on the far side of the moon.
News
By Leonard David( space.com-leonard-david ) published March 21, 2024
https://www.space.com/the-moon-far-side-radio-silenceBut it may also provide an ideal means to search for radio SETI.
Bob Clark
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Common Sense Skeptic, a well-known critic of SpaceX, presents an argument that considering all the mission objectives IFT-3 should not be regarded as a successful test:
From the video :
Bob Clark
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On 3/27/2024 at 8:09 PM, tater said:
How about showing it can get anywhere near the 150 tons payload to LEO claimed?
What IFT-3 showed was a launcher with 0 tons to LEO payload capability, even when fully fueled and fully expending its propellant. Then how can it do Artemis Starship HLS refuelings when it gets 0 tons to LEO?
Bob Clark
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12 hours ago, tater said:
Glad they didn’t call this 5-second burn a “full duration” fire.
Bob Clark ;-)
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5 hours ago, darthgently said:
Deja Vu! This exact issue posed by exo has been addressed exhaustively and authoritatively over the last few months. It's like we are in a Moebius time loop!
SpaceX repeating the same mistakes over and over again does not make those mistakes correct.
Bob Clark
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10 hours ago, Cuky said:
If test parameters are "Start all 6 engines, keep them on for 10s and then shut down and have no problems during all of that" and they burn for those 10s that means that full duration of the test was performed. How is that so hard to grasp for so many static fires and pages of this thread is beyond me really.
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The problem is that is not standard usage in the industry. Commonly, you run an engine in static tests at full thrust and full fight duration to give confidence it can perform as expected during actual flights. This is also done as confirmation to potential customers that the rocket will actually deliver as expected.
Blue Origin could if they wanted call their little suborbital hops with New Shepard as “flights to orbit”, but that doesn’t mean the rest of the industry would agree with that terminology.
Bob Clark
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7 hours ago, tater said:
Sorry, but a 10 second burn is not “full-duration”. THIS is full-duration:
Another irritation of mine is that SpaceX won’t tell you what power level their tests are operating at. 50%, 75%, 100%? Usually, the launch company tells you that in their tests to confirm to potential customers their engines can operate at the needed power levels to complete their missions.
Bob Clark
). Mostly dents and dings. Am surprised there are no moves to build some protection for the tank farm, for example.
A route to aircraft-like reusability for rocket engines.
in Science & Spaceflight
Posted · Edited by Exoscientist
I am arguing that NASA was blindsided by the low 40 to 50 ton capability of the current version of the SuperHeavy/Starship. A couple of reasons why I say this. First, while Elon was extolling the “success” of the latest test flight in his recent update at Starbase on the Starship development, NASA soon after wards started making plans for use Starship in Artemis III that won’t use the Starship as a lander. (NASA did not openly reveal this; it had to be leaked.) Note also the proposed options NASA is considering also would not use refueling of the Starship. The low 40 to 50 tons to orbit would cause impractically large number of refueling missions. Then V2 or even V3 would be needed for this and I’m suggesting NASA believes neither of those would be ready by Artemis III.
Note the SpaceX plan for a lander using multiple refuelings absolutely can not work if the Raptor can not operate reliably for both boostback and landing burns. Relighting, apparently, successfully at boostback is not sufficient if a Raptor explosion on landing causes vehicle RUD.
So I’m also arguing NASA has no confidence SpaceX can solve the relighting reliability issue, that requires three Raptor firings per flight both for the booster and ship, by Artemis III.
Beyond that, another key reason why I say NASA was blind-sided by the low payload capability of the current version is if you run the numbers SpaceX cited for the specifications on the current version, it should easily make 100+ tons to orbit even as a reusable. That it makes at best half that suggests the dry mass or Raptor values or more likely both are significantly worse than the values cited by SpaceX.
Bob Clark