Exoscientist

I wouldn’t call it groundbreaking. The ISRO scientists just said it was “unexpected”. What would be ground-breaking if the instruments on the rover for detecting water did find it at high abundance. By the way, in regards to the point that nether India nor China have evinced any interest in exploiting the resources on the Moon, it is interesting that India is a signatory to the Outer Space Treaty. The purpose of the treaty was to prevent the wealthy spacefaring countries like U.S., Europe, Japan, Russia, China from exploiting the resources in space to the detriment of the underdeveloped countries, such as India. Quite ironic then that India, one of the countries the Outer Space Treaty was designed to protect, may be a country best in line to exploit those resources IF, and that’s a big IF, their rover confirms the large amounts of precious metals suggested by orbital observations. Follow along with me on this hypothetical scenario: suppose India does discover these high levels of precious metals. As a signatory to the Outer Space Treaty they are obligated to share this information with the world. But suppose the amounts they found suggest literally trillions of dollars worth of precious metals. They are still an underdeveloped country. The leadership in their country would understandably ask themselves this question: what is in India’s best interests? Bob Clark

Chandrayaan-3's Vikram lander records 70 degrees Celsius on moon surface, ISRO says 'higher than expected' 2 min read 29 Aug 2023, 09:23 AM IST ISRO on 27 August released a graph of the temperature variation on the lunar surface and a senior scientist of the space agency has expressed surprise over the high temperature recorded on the Moon. https://www.livemint.com/science/news/chandrayaan3s-vikram-lander-records-70-degrees-celsius-on-moon-surface-isro-says-higher-than-expected-11693280333275.html Bob Clark

It’s described more in articles describing the experiment. Just a few millimeters below the surface the temperature got to 70 C. It wasn’t expected to get that high. ISRO scientist speculate large amounts of water allow the near subsurface to retain that heat. The rover does have specific instruments to confirm there really is water there. I’m looking forward to the APXS deployment. It can detect heavy metals. It would have world-changing implications if it confirms the high abundances of precious metals there suggested by the LCROSS mission from orbit. Bob Clark

Chandrayaan-3 already returning exciting, unexpected data:

The Saturn V F-1 engines were tested all together multiple times at full thrust and full flight duration static tests: And SpaceX has tested the Falcon 9 for full thrust, full flight duration tests: As for the reason for doing a full 100% thrust static test firing, the test launch back in April showed testing at 50% was not sufficient to show the launch procedure was safe. That’s just for the 5 second long tests SpaceX wants to do. I don’t think they fully fill up the vehicle with propellant during these short tests for safety’s sake. But as I mentioned I don’t agree these 5 second tests are adequate. They didn’t pick up how many engines would fail and even explode as happened in the April test launch. Again, instead of dismissing the lessons of Apollo, SpaceX should learn from them. Construct a separate test stand to do full up, full thrust, full flight duration tests like was done with the Saturn V first stage. Bob Clark

I am dismayed by the level of unreliability of the Raptor. In this latest static fire test two of the Raptors had to be shut down for only a 5 second test and 50% thrust level. But this is the same number that had to be shut down in the earlier static fire test prior to a test launch for only a 5 second test at 50% thrust level. Does anyone really believe the Raptor is more reliable than before? At this point I don’t think anyone doubts that if there is another test launch in like two weeks there will be engine failures like before. The only question is how many. Will it this time be only four or six instead of eight? Or this time will it be 10 or 12 or more instead of eight? Nobody not even SpaceX knows the answer to that. Bob Clark

Actually, I think they should go back to the approach they took with the Falcon 9. First, make a smaller rocket with, say, 9 Raptors such as the Starship but used as the booster, with a smaller stage, call it a mini-Starship, as the upper stage. Test the heck out this vehicle at full up, full thrust, and full flight duration static tests. Just they like did and still do for the Falcon 9, before they do a test launch. Only after multiple full static tests where all engines successfully pass do they send this up for a test flight. Such a two-stage rocket could do 100 tons to LEO. That is sufficient to do single-launch lunar and Mars missions. Now, make money on that rocket made from the start to be reusable. Fly that rocket very many times all the while making profit with it. THEN after flying so many times you accumulated like over a 1,000 successful firings of the Raptor on full actual, operational flights then form your superheavy lift vehicle by using triple cores, like what happened with the Falcon Heavy. That is if you still want the superheavy lift vehicle. My guess is you’ll be making money on the smaller version and be able even to make both single-launch Moon and Mars missions with it, there will be little incentive to continue on with the larger vehicle. See: The Missed Lesson of the Falcon Heavy. https://exoscientist.blogspot.com/2023/02/the-missed-lesson-of-falcon-heavy.html Bob Clark

Except when those eggs might be other people’s heads. Bob Clark Sorry, SpaceX used up their “because SpaceX says” so cred, by their no flame trench, poor FTS, bad stage separation mistakes. If they think this water deluge system will work at 100% thrust, then prove it by actually testing it at full thrust. Bob Clark

“Fool me once, shame on you. Full me twice, shame on me.” Bob Clark

This static test fire was again at only 50% thrust level. We were misled into thinking a 50% test was sufficient to judge the full thrust burn the last time. The only way to be sure is to do a full thrust static burn to judge the water deluge system then. Bob Clark

Does SpaceX want to hide that some engines had to be changed after the last static test? Robert Clark

No. The discussion was about using the SLS for cargo. I think it is too expensive for that purpose. Use the Falcon Heavy for that purpose, or other low cost commercial launchers. No crew module would be included here. I was talking about using two hydrolox stages to get the max cargo on the Falcon Heavy but here’s another way using a single stage: Suppose we use a 45 ton prop load “Centaur-like” stage carried to LEO by the Falcon Heavy for cargo only transport to the lunar surface one-way. As it’s Centaur-like, take the ISP as 465.5s(the max Centaur RL-10 Isp with extended nozzle was 465.5s); and give it a ca. 10 to 1 mass ratio, so a dry mass of 4.5 tons with the 45 ton prop load. Then with 12 tons payload you could get: 465.5*9.81LN(1 + 45/(4.5 + 12)) = 6,000 m/s, which is sufficient for the stage to do both TLI and land on the lunar surface one-way with the 12 tons of payload. But the need for low boiloff for the 3-day flight to the Moon would reduce this payload somewhat. Alternatively, you could let the FH do the TLI burn, and say it could get ca. 20 tons to TLI. Use a 10-ton “Centaur-like” stage, at 10 ton prop load, 1 ton dry mass, and 465.5s ISP. Then it could get 9 tons payload one-way to the lunar surface: 465.5*9.81Ln(1 + 10/(1 + 9 )) = 3,160 m/s, sufficient for the lunar landing once already put on the trans-lunar trajectory to the Moon by the Falcon Heavy. Bob Clark

The current # of mirrors on ELT is 800. Only adding 30 more brings the diameter from 39.3 to 40 meters. You know there’s a considerable psychological effect of that first digit, reason why retailers like pricing their products at $39.95 rather than $40. Having the telescope size at 40 meters puts its size in good stead in relation to the 100 meter, cancelled, OWL telescope. Large ground, segmented mirror telescope costs scale by collecting area, i.e., by square of aperture diameter. Increasing the size by a factor of (40/39.3)^2 would add an additional 3% to the $1.5 billion dollar cost, or $50 million. I’m sure all astronomy enthusiasts world-wide would be willing to add that extra $50 million to bring its size up to 40 meters. Bob Clark

I’ve seen numbers for Falcon Heavy to TLI in the range of ~20 tons NASA chief explains why agency won’t buy a bunch of Falcon Heavy rockets. “It’s going to be large-volume, monolithic pieces that are going to require an SLS.” ERIC BERGER - 3/26/2018, 3:23 PM SpaceX has not publicly stated the TLI capacity of the Falcon Heavy rocket, but for the fully expendable version of the booster it is probably somewhere in the range of 18 and 22 tons. This is a value roughly between the vehicle's published capacity for geostationary orbit, 26.7 tons, and Mars, 16.8 tons. https://arstechnica.com/science/2018/03/nasa-chief-explains-why-agency-wont-buy-a-bunch-of-falcon-heavy-rockets/ But to maximize payload don’t use the kerolox FH upper stage to do the TLI burn. Use the 63.8 ton FH capacity to LEO to carry hydrolox stages for the TLI burn and for the lunar lander stage. For example a 30 ton Centaur-like stage with a 10 ton Centaur-like stage could get about 15 tons one-way to the lunar surface. This assuming low boiloff tech for the lander stage. By “Centaur-like” I mean getting high vacuum Isp and high, for hydrolox, mass ratio also. Robert Clark

Too bad about Luna-25 but one of the rovers sent to the lunar South Pole has to succeed. If the precious metals suggested to exist there by multiple lines of evidence is confirmed then we may finally have the “killer app” that not just for spaceflight to LEO brings us low-cost by large number of flights, but even interplanetary flight as well. See this article on the detections by the LCROSS orbital mission: Prospecting for native metals in lunar polar craters. January 2014 Warren Platts, Dale Boucher, George Randall Gladstone ABSTRACT One of the more astonishing results of the LCROSS mission were spectra indicating large concentrations ofnative precious metals. We hypothesize that the reported metal concentrations represent electrostatic placerdeposits: we theorize that electrostatic dust transport preferentially favors transport of submicron-sized nativemetal particles that get trapped in permanently shadowed regions (PSRs) within much smaller subareas wheresolar wind wake effects are minimal. We review the LRO LAMP and SSC UV/VIS data and note that severalspectral emission lines in the UV are consistent with the presence of platinum, as well as silver and gold. Wealso conduct a numerical simulation that shows that levitation of submicron-sized gold particles is favoredcompared with dielectric dust particles. We then develop an ore genesis model that predicts a soil massabundance of 0.11% for Au within the ore body trap that is in rough agreement with the estimate of 0.52% forAu based on the LRO LAMP column density observations. We apply the same methodology to Hg, and predicta soil mass abundance of 0.53% Hg, compared with an estimated 0.39% Hg based on LRO LAMP columndensities.Greenfield ore grades are determined initially by remote sensing techniques and ore body genesis modeling;secondly by exploratory drilling and sampling; and finally by close-in ore body delineation (detailed samplingand analysis) to provide a 3D picture of the ore body of interest. Now that we have in hand a large body ofvarious remote sensing data sets, and a predictive ore genesis model, we propose to undertake the second step—exploratory drilling. Since the occurrence of electrostatic placer deposits tends to coincide with deposits ofvolatiles, the upcoming Resource Prospector Mission (RPM) will be in an ideal position to detect native preciousmetals as well as volatiles. However, the Lunar Advanced Volatile Analysis (LAVA) instrument can onlycharacterize volatiles below 70 AMU, whereas Ag, Pt, Au, and Hg atoms range in mass from 108 to 200 AMU.Therefore, we propose that an “X-Ray Spectrometer System” (XSS) be added to the RPM rover as a secondaryscientific payload. The XSS instrument will primarily consist of an X-ray fluorescence detector (XRF) thatoffers the right combination of low mass, low power requirements, high speed, and high accuracy (ppm levelfor heavy precious metals). Finally, since water derived from PSRs will eventually be intended for humanconsumption, the likely high concentration of Hg in PSRs is a potentially grave health hazard, and representsa huge knowledge gap in our understanding of how to work and live on the lunar surface that is left unaddressedby the RPM in its present configuration (PDF) Prospecting for native metals in lunar polar craters. Available from: https://www.researchgate.net/publication/286162525_Prospecting_for_native_metals_in_lunar_polar_craters [accessed Aug 21 2023]. Bob Clark

I’ve been thinking about the possibilities of what the upcoming lunar rovers to the Moon’s south pole might find. Too bad about Luna-25, but at least one of the rovers has to succeed. Multiple lines of evidence suggest there may be precious metals there. In that case there would be an economic motive for going to the Moon. In such a scenario more commercial approaches to lunar access would be tried. Robert Clark

SLS at $2 billion per flight shouldn’t be used for cargo. It should only be used for carrying astronauts. For cargo and habitats use the Falcon Heavy. For in-space hydrolox stages on the Falcon Heavy, I estimate 15 tons one-way to the lunar surface if you have low-boiloff tech. If only the stage for TLI is hydrolox, so you don’t need low boiloff, and with a storable propellant lander stage I estimate 10 tons one-way. For Falcon 9 launches it would be 1/3rd of those numbers. Since the crew lander would be only to transfer astronauts to a lunar habitat already stationed and provisioned there the lander could be LEM sized at ca. 15 tons. By the way the total cost for SLS and Orion of $4 billion per launch is unsustainable. For an sustainable presence on the Moon we need cheaper lunar access. The Starship could do it if it gets operational, but I don’t like the multiple refuelings for a single mission. Robert Zubrin noted if you gave the SH/ST a smaller 3rd stage, then it could do single-launch missions to the Moon and to Mars. Edit: I looked it up and the Falcon 9 with cargo Dragon can carry 3,300 kg to the ISS. So with all-hydrolox low boiloff in-space stages, it could get, at a payload of 5,000 kg to the lunar surface, more payload than the Falcon 9/Dragon gets to the ISS. Or by using a hydrolox stage only for TLI, no low boiloff required, with a storable prop lunar lander stage, it could about the same as the F9/Dragon to the ISS at ca. 3,000 kg. The reason why the F9 going all the way to the Moon can get at or more payload than its payload to the ISS is firstly it wouldn’t use the cargo Dragon at 4 tons for the lunar lander and secondly hydrolox is more efficient for upper stages than kerolox. Bob Clark

That was for missions that first went through the Gateway. We’re trying to avoid that. The proposal of using existing ESA space assets to create the lunar lander built by the ESA, would save $3 billion from NASA’s Artemis budget by eliminating the SpaceX lander. And removing the Gateway would delete another $4 billion. That’s $7 billion saved by NASA for the Artemis missions. Bob Clark

I’ll take a look at your calculations and let you know what I think. You appear to be someone who likes delta-v calculations. In that case, take a look at the two cases considered here, the two Vulcain case and the three Vulcain case: Bob Clark

Could be. Any one know of images of the water deluge steel plate after the test without the static burn? Was it covered by a tarp as well then? Bob Clark

The steel deluge plate is covered by a blue tarp there. Bob Clark

Saw this on Reddit: SpaceX tearing up some sections of the concrete after the latest static fire test. Also have they revealed what’s under the tarp covering the steel plate after the deluge: Robert Clark

Sorry, but this is incorrect. Shockwaves or any kind of wave can be reflected any direction. This is a key point. Take a look at this video by Everyday Astronaut: The reverberating shockwaves visible at the 1:57 point in the @Erdayastronaut video suggest the SpaceX approach to water deluge can damage the engines. SpaceX should stop dismissing the lessons of Apollo and learn from them. Use a flame trench. Robert Clark

When impinging on another object liquid, gas, or solid they can travel in any direction, like a ball headed backwards after hitting a wall. Explosion shockwaves for example can bounce off of atmosphere layers and bounce back to Earth known as atmospheric focusing: Atmospheric focusing is a type of wave interaction causing shock waves to affect areas at a greater distance than otherwise expected. Variations in the atmosphere create distortions in the wavefront by refracting a segment, allowing it to converge at certain points and constructively interfere. In the case of destructive shock waves, this may result in areas of damage far beyond the theoretical extent of its blast effect. Examples of this are seen during supersonic booms, large extraterrestrial impacts from objects like meteors, and nuclear explosions. https://en.wikipedia.org/wiki/Atmospheric_focusing Robert Clark

This @Erdayastronaut clip shows quite alot of water reaching the level of the engines even though the water is angled outwards at the base. Then depending on the pressure of the water at this height, the exhaust flow impinging on it can cause reverberating pressure waves back on the engines. In the 5+ second Booster 7 static fire in February, only two engines failed. In the test flight in April with a longer time on the pad to liftoff with a veritable concrete tornado throwing up chunck’s of concrete, only 3 engines failed in the initial liftoff. In this latest test, 4 engines failed after only 2.7 seconds. Cause: the water deluge. Robert Clark