Exoscientist

The irony of the rapid development of hypersonics is that it will be replaced not very long after with fusion propulsion. That’s the thing with being in the exponentially rapid advancement part of the curve. Why spend a great deal of money on something when by the time you have it operational it will be made obsolete by another advancement? Bob Clark

Thanks for the informative post. I’m a fan of Peter Diamandis series of books on “exponential technological advance”. He makes the point that some tech advance can seem very slow, in fact stagnant. This was the case with nuclear fusion research for example for decades, and also with hypersonics. But then it reaches an inflection point and the technology advances exponentially. I believe that is where we are at with fusion and hypersonics. The Future Is Faster Than You Think: How Converging Technologies Are Transforming Business, Industries, and Our Lives (Exponential Technology Series) https://www.amazon.com/Future-Faster-Than-You-Think-ebook/dp/B07TD6GPVR/ Bob Clark

Re-sent using unformatted text. Bob Clark

No, I don’t mean SpaceX. Several companies rather are investigating hypersonic air-breathing vehicles. These are vehicles that draw the oxidizer from the air like jet engines. Reaching hypersonic speeds would be to Mach 5+. The easiest approach to these speeds is to use ramjets. Scramjets can reach even higher speeds but are a much more difficult technological task. I found the most promising approach that taken by Hermeus. They were able to keep costs down by using already existing turbojet engines and modifying them to operate in a ramjet mode: But a key fact about the hypersonic air-breathing vehicles is how much they can subtract off from the delta-v needed to reach orbit. Mach 5.5 is about 5.5*340 m/s = 1,870 m/s. But ramjets can also operate at quite high altitudes, well above standard turbojets, to about 30+ km, 100,000+ feet. The equivalent delta-v for that altitude is about 800 m/s. Then ramjets can supply 1,870 + 800 = 2,670 m/s delta-v to orbit. It turns out the trajectories that use aerodynamic lift can subtract some amount from the needed delta-v to orbit, so call it 9,000 m/s needed for orbit using lifting trajectory. Then the delta-v that needs to be supplied by the upper stage would be 9,000 - 2,670 = 6,330 m/s. For expendable rockets the first stage commonly supplies about 4,000 m/s total delta-v speed+altitude with about 5,000+ m/s being supplied by the upper stage. But for rockets for which the first stage will be reusable like the Falcon 9 and the Superheavy booster, they supply a smaller total delta-v speed+altitude to the flight of about 3,000 m/s. This is so they can boost back to the launch site more easily. Then this means the air-breathing hypersonic vehicle can supply about the same total delta-v, speed+altitude, as the reusable booster. But the majorly important advantage is the air-breathing vehicle can be reused thousands of times, compared to only a few ten's of times for the rocket booster. Since the first stage by virtue of its large size commonly takes up 75% of the cost of a launcher, this means the cost of launch will be greatly reduced when that first stage can be reused thousands of times. The implications of this will be immense. It means for example despite SpaceX spending billions developing the SH/SS it may already be obsolete just by 2025 when hypersonic vehicles become operational and are used as the first stage of an orbital vehicle. The implications don’t seem to be recognized by these companies developing the hypersonic aircraft. They only discuss using them for hypersonic transports or hypersonic missiles. The applications to low cost, high reusability first stages does not seemed to be realized. If Hermeus succeeds, then it will become important to recognize how that success can be repeated by other companies in the aerospace industry. The adapting of existing turbojet engines to hypersonic turbo-ramjet hybrids as described by Hermeus is not particularly advanced technology nor of high cost. Other companies can repeat it as well. I advise though not just adapting the existing turbojet engines but also adapting existing supersonic aircraft. Hermeus built their own hypersonic test vehicle. Costs could be cut further by adapting an existing supersonic airframe as well as its supersonic capable engine. The result will be the democratization of hypersonic transport aircraft, and thereafter the democratization of spaceflight. I think the hypersonic advance will be successful, and it will thereby be used to launch payloads to orbit as a first stage, greatly reducing costs. However, I think it possible it will also make possible another key advance: combined air-breathing/rocket SSTO's. The designers of Skylon have argued this will be possible with their Sabre engine able to reach Mach 5.5. The problem with Skylon is it's projected $12 billion development cost. But by adapting already existing turbojets to ramjets, and utilizing existing airframes plus an existing hydrolox stage for the rocket portion of the flight this cost can be radically reduced, perhaps to only 1/100th of that, a few hundreds of millions of dollars. See discussion here: Low cost approach to winged, air-breathing and rocket SSTO's, Page 1. https://exoscientist.blogspot.com/2024/06/low-cost-approach-to-winged-air.html Robert Clark

Do you have a link to that video? Considering how advanced nuclear power is I could believe the idea it’s a “21st Century technology”, but calling it a 23rd century technology like when Star Trek is supposed to be happening is too far out in time(no pun intended.) Bob Clark

If Blue Origin continually referred to their little suborbital hops by New Shepard as “flights to orbit”, it would then be accepted in the rest of the industry they are flights to orbit. You just have to keep repeating it. Bob Clark

The most comprehensive review of the health effects of long term life in deep space is in the two book series by Dennis Chamberland, a former NASA life sciences engineer: Departing Earth Forever: Book One - Warning and Promise: The Manual for Today's Colonists Preparing to Launch to Mars and our Moon. https://www.amazon.com/Departing-Earth-Forever-Colonists-Preparing-ebook/dp/B0B5NH4Z61/ And: Departing Earth Forever: Book Two - Alien Worlds: The Manual for Today's Colonists Preparing to Launch to Mars and Our Moon. https://www.amazon.com/Departing-Earth-Forever-Colonists-Preparing-ebook/dp/B0B72HX8MX/ Though he was formerly with NASA Chamberland has a dim view view of NASA’s approach to safety for such long space flights in deep space. Bob Clark

Following the SpaceX lead, this now counts as a “full duration” burn. Bob Clark

This added onto the known dangers of zero-gravity and cosmic ray damage after long deep space exposure is why I favor fast flights to Mars: http://exoscientist.blogspot.com/2015/08/propellant-depots-for-interplanetary.html With propellant depots in place we can do flights to Mars in about a month with just standard chemical propulsion. No ion drive, or nuclear propulsion, or advanced propulsion methods required. It can even be done with a Falcon 9 first stage at approx. 400 ton propellant load. It can also be done with the Starship, and SpaceX wants propellant depots anyway. BUT to get the fast trip, SpaceX would have to go back to the ca. 40 tons dry mass of the expendable Starship: Bob Clark

So as I argued before SpaceX should investigate an expendable version of Superheavy/Starship. The Raptor has been in development since 2016 and it is still experiencing explosions during relights. The Falcon 9 was spectacularly successful by first developing it as an expendable, doing several profitable, commercial flights in the expendable form, then progressing to the reusable form. Note all those successful, expendable flights gave good information on the Merlins reliability. A majorly important advantage of going first with the expendable form of the SH/SS is that we can do both single launch Moon and Mars missions now by using the Falcon 9 upper stage as a 3rd stage/lander stage and the Dragon as the crew module. (The Orion capsule is overbloated both in cost and mass.) Going with the expendable form of the SH/SS means you get greatly increased payload to LEO now , probably in the 250 to 300 ton range, by not having to keep the large amount propellant on reserve for the SH for return to launch site, and you wouldn't get the tripling of the dry mass of the SS for reusability systems we have now. For either of those manned flights to the Moon or Mars, this would be around the cost of a SH/SS single launch, $95 million. Compare this to the likely $7+ billion per mission cost of Artemis when you add up all of SLS, Orion, Starship HLS, Boeing EUS, advanced booster upgrade, and Gateway costs. And compare it to $500 billion(!) cost NASA once estimated for the full development costs of a manned Mars program. Quite importantly also, we could do it, literally, like, tomorrow. Not by 2028 for going to the Moon by the Artemis architecture, and not by the 2030's for Mars by the most optimistic estimates by Elon Musk. Bob Clark

I think it is fairly obvious why they didn’t want to show what happened after that. Bob Clark

The problem is the Raptor is still exploding on relights, as happened on both booster landing burns. Bob. Clark

Thanks for that. I was wondering if any of the splashdown areas would be observable from satellite imaging. Planet Labs claims to provide continuous, world wide imaging at 3.7 meter resolution, but I found their coverage quite spotty. I couldn’t find images of the expected landing areas. Perhaps someone would be able to find it. Real-Time Satellite Monitoring with Planet. With roughly 200 Dove satellites in orbit, PlanetScope Monitoring provides a high-resolution, continuous, and complete view of the world from above, every day. https://www.planet.com/products/monitoring/ Bob Clark

The Raptor had consistent problems of leaking fuel and catching fire on relights on prior tests of the Starship landing procedure: Even on the SN15 test that SpaceX called a “success” because it landed without exploding, a fire had developed in a Raptor before it touched down. SpaceX was just able to extinguish the fire before it exploded. My opinion, it was mistake for SpaceX to stop these Starship landing tests because SN15 landed without exploding first. The tests should have continued until all Raptors were able to do all the relights needed with no engines catching on fire. That is a necessary requirement for a reliable, reusable engine. And on IFT-3 and just now on IFT-4 a Raptor exploded on relight during the landing burn. SpaceX would do well to remember the famous warning of Richard Feynman after the Challenger disaster, “For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled." Bob Clark

There still is the issue the engine lit indicators on the SpaceX video stream did not light up for the ship landing burn. Note that for both this flight and previous flight they did correctly light up for landing burns. EDIT: the engine lit indicators worked correctly both times showing which engines fired during the landing burn for the booster. Bob Clark

I was watching a stream without the SpaceX commentary. Was there a call out that at a certain time during reentry there was supposed to be an engine firing to slow down the ship? Obviously, the degree of damage to one of the flaps during reentry was not normal, which suggests there should have been a burn then. There is uncertainty if there was a landing burn for the ship just before touchdown. The graphic at the bottom right showing which engines are lit did not come on. On the other hand the ship did reorient itself just before landing. It is possible the RCS and the flap control surfaces are sufficient to reorient the ship when tanks are near empty. A major irritation of mine is SpaceX is continuing to promote the idea the Raptor is already at sufficient reliability level for an engine intended to carry crew. The reality is it is nowhere near that level which should be 99.9+% Bob Clark

Is it possible the high temperature alloys used for the engine combustion are being confused with the metals used for the tanks? Bob Clark

Good that both booster and ship managed to reach the surface albeit clearly in a damaged form. But I repeat my earlier complaints, the Raptor is nowhere near the reliability level needed for a reusable engine. The Falcon 9 was spectacularly successful by first going for an expendable launcher. Then, progressing towards reusability. If SpaceX had taken that approach with the Starship, they would already be making operational launches, and making a profit on those launches. And it could be making single launch flights to both the Moon and Mars now. No refueling flights or even SLS required. Also, by now both SpaceX and the FAA must acknowledged there is a problem with the Raptor reliability. No mishap reports required my rear end! Robert Clark

FAA grants Starship launch license with wide latitude: https://twitter.com/marcushouse/status/1798136232402370622 Nice cover by SpaceX beforehand asking the FAA not to require a mishap report if any of these cited failings occur. SpaceX can then continue to point the finger away from the Raptor as the cause. A question: shouldn’t SpaceX be required to answer questions honestly to the FAA, the agency responsible for launch safety? Then here is a majorly important question that SpaceX needs to answer to the FAA, and the FAA as a public agency should be expected to ask: Was the apparent fuel venting seen for *both* the booster and ship after their burns actual fuel leaks? If so, that suggests the problem is with the Raptor itself: https://x.com/djsnm/status/1768268571531235669?s=61 https://x.com/nricolas360/status/1785764709313946057?s=61 https://x.com/goingballistic5/status/1769401675687579764?s=61 It is notable as well in the recent Raptor test stand explosion that there was a fuel leak first, then the RUD occurred. This goes directly to the question of whether the Raptor has the tendency to undergo fuel leaks, further justifying the necessity of asking the question if there were fuel leaks after both stage’s burns. Bob Clark

I can see your posts. Bob Clark

IF the fuel venting seen for both the booster and ship after their burns was real that suggests the problem is with the Raptor itself. It is also notable that in the recent test stand explosion there was a fuel leak after the engine start, the engine was shutdown, and then the RUD occurred. Then this is a highly important question for SpaceX to answer, and for the FAA to ask about, if whether the fuel or LOX venting seen on both stages after their burns was real or not. Bob Clark

Just released video by “Angry Astronaut”: SpaceX asks the FAA to bend the rules and return Starship to flight NOW! PLUS RFA ONE static fire!! https://www.youtube.com/watch?v=nG8T2HUe-Lo Points out the point I’ve been making. The reason SpaceX still has not released a mishap report is they do not want to acknowledge the reason the booster failed on landing is the Raptor still has the problem observed previously of leaking fuel on relights: Starship SN8 SN9 SN10 SN11 SN15 High Altitude Flight test synced. https://m.youtube.com/watch?v=Ww83pSeuGuA But I don’t agree with “Angry Astronaut” in his video where he says, IFT-3 offered no danger to the public so Starship can be recertified by the FAA to fly without a mishap report. The booster landed far outside the expected landing zone, probably because of flaws in the Raptor firing during the boostback burn. It should have landed 30 km off shore, but actually landed ca. 100 km off shore: Starship Booster 10 Descent Simulation. https://m.youtube.com/watch?v=O6a10KbkGro It could have been a danger to fishing or shipping in the area where it landed unexpectedly. Bob Clark

The concept Artemis is cheaper than Apollo was in response to this video: NO WAY we’re landing on the moon in 2026. https://youtu.be/pQufaHiAark?si=gYJKXgzQf-hjkuiv About at the 5:25 point is mentioned a NASA lunar lander might normally be developed for $10 to $20 billion. And in this link about the cost of Apollo, the total costs of the Apollo lunar lander over the entire Apollo program adjusted to 2020 dollars did indeed cost ca. $20 billion: https://www.planetary.org/space-policy/cost-of-apollo For the seven Apollo lander missions that’s in effect ca. $3 billion per mission. The contract NASA gave SpaceX for the Starship HLS totals about $4 billion for two lander missions, or $2 billion per mission. That’s not a terribly great saving over what we did during Apollo. Even worse, that’s the same as the cost for the entire SLS rocket, with the two SRB’s, the core stage with the four over-priced reincarnations of the SSME’s, and interim upper stage. But the key point I’m making is considering how much the space program in general has developed world-wide now, with a wide variety of launchers, in-space stages, and spacecraft, we can use essentially off-the-shelf components to construct a lunar lander. And as SpaceX has shown costs are cut drastically if the spacecraft is privately funded. So don’t construct the lander from scratch, which as experienced space observers we know makes costs balloon greatly, and don’t use the typical government financed approach, which we also know make costs balloon greatly, instead use already existing and operationally in use components and use private funding to construct it. In this, way the lander might only cost in the tens of millions range, instead of billions. Dave Masten gave another interview where he discussed his Centaur-derived lunar lander: Spacevidcast Live - What if Apollo never happened? https://youtu.be/oQ4lLTblx5M About 30 minutes in, he suggests its costs would be ca. $50 million to purchase the Centaur, and only a few more million to add on Masten’s side thrusters for horizontal landing. Plus, some millions more for testing. The host suggests under $200 million total, and Masten responds, “Oh, easily.” Bob Clark

The concept of Artemis being “better” than Apollo based on cost grounds comes from this assessment of Apollo’s costs in inflation-adjusted dollars: How much did the Apollo program cost? The United States spent $25.8 billion on Project Apollo between 1960 and 1973, or approximately $257 billion when adjusted for inflation to 2020 dollars. Adding Project Gemini and the robotic lunar program, both of which enabled Apollo, the U.S. spent a total of $28 billion ($280 billion adjusted). Spending peaked in 1966, three years before the first Moon landing. The total amount spent on NASA during this period was $49.4 billion ($482 billion adjusted). https://www.planetary.org/space-policy/cost-of-apollo The max expenditure in a single year was ca. $45 billion in 2020 dollars. And the total cost of the lunar lander alone was ca. $20 billion in 2020 dollars. The total cost of Artemis so far is ca. $50 billion: The Cost of SLS and Orion From its inception in 2011 through the year of its first flight, the Space Launch System rocket program has cost $23.8 billion. The Orion deep space capsule has cost $20.4 billion since the program began in 2006. Related ground infrastructure upgrades cost an additional $5.7 billion since 2012. In total, NASA spent $49.9 billion on these programs between 2006 and their first test launch in 2022. https://www.planetary.org/space-policy/cost-of-sls-and-orion But how much cheaper Artemis is than Apollo exemplifies another key advantage we have now over Apollo that we must make use of: the plentiful commercial launchers, in-space stages, and spacecraft already operational and in regular use. Then USE that advantage. Construct your lander, small like Apollo’s, from EXISTING components, not developing the lander from scratch. Knowledgeable observers of the space program are aware of the fact development costs for entirely new systems from scratch incur ballooning costs. There are multiple ways of following this approach. Here’s one: Possibilities for a single launch architecture of the Artemis missions, Page 3: Saving the lander mission for Artemis III. https://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch_11.html Bob Clark

This can’t be correct for a minimal lander to and from low lunar orbit since we know Apollo LEM was able to do it at ca. 15 tons gross mass. Bob Clark