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SpaceX Tests Its Raptor Engine For Future Mars Flights (techcrunch.com)
Thelasko writes: Elon Musk is preparing to unveil his plans to colonize Mars at the 67th annual International Astronautical Congress tomorrow. As a tease to his lecture, he has released some details about the Raptor engine on Twitter, including pictures. Mr. Musk states that, "Production Raptor coal is specific impulse of 382 seconds and thrust of 3 MN (~310 metric tons) at 300 bar." He goes on to note that the specific impulse spec is at Mars ambient pressure. The Raptor interplanetary engine is designed for use with Space X's Mars Colonial Transporter craft. Musk notes that the "chamber pressure runs three times what's present in the Merlin engine currently used to power Falcon 9," according to TechCrunch. "Merlin has specific impulse of 282 seconds (311 seconds in the vacuum of space), and a relatively paltry 654 kilonewton (0.6 MN) at sea level, or 716 kN (0.7 MN) in a vacuum. You can view a picture of the "Mach diamonds" here, which are visible in the engine's exhaust.
In before someone comments that they can't do R&D while simultaneously sorting out the recent problems with the Falcon 9.
People can multitask, companies even more so. If they were still blowing up every vehicle on the pad, then maybe they'd have a point, but their systems are certainly working better than other programs at their stage of evolution.
Trying to become famous by taking photos. Visit my homepage please.
Before someone comments that we don't need humans on Mars if robots can do the same cheaper: that's beside the point. I mean, robots are no where near performing on the same level as humans when it comes to ingenuity and ability to come up with and implement ad hoc fixes to problems that no one could even imagine before launch of the mission. But putting that question aside, the problem with robotic missions is that they will never get the same sort of funding as human missions. A human mission automatically has to have a certain size, e.g. has to develop capabilities to land payloads in the ballpark of 10 tons or more on Mars. Once we have this capability, we can easily send lots of robotic and scientific payload along with humans -- it amounts to simply using the same payload delivery system that we are developing for humans anyway.
On the other side, if there is no ambition to fly humans to Mars, then no one will develop these capabilities. There is simply no funding for a system that delivers 10 tons of cargo onto the surface of Mars, unless it can also deliver humans, and bring them back safely. So we cannot send big robotic missions to Mars.
Human missions generate lots of excitement, lots of excitement leads to lots of funding. Robotic missions can never be on par with human missions in terms of how much excitement, and thus funding they can raise.
It's 382 in vacuum for the vacuum version of Raptor. Why mention the 311 s figure of Merlin with the 3 MN that the Merlin doesn't have?
Ezekiel 23:20
Even if you didn't go for Mars, this would still be a major item on the list of things you need to do in order to hurl big stuff into Earth's orbit more affordably. There are long waiting lists of customers for such capability.
Ezekiel 23:20
Indeed. Part of the reason that satellites are so expensive is how light you have to make everything; there's a huge amount of engineering that has to be done in order to achieve mass goals, as well as make use of the most expensive materials on the planet. An example is the use of things like top-end Spectrolab multi-junction solar cells, which get the highest efficiencies, but since they're basically lab-scale production hardware they cost two orders of magnitude more than what slightly less efficient panels on Earth cost (about $400/W).
Beyond the simple cost effect on engineering, there's the size effect. Look at James Webb and the massive expense they had to try to make it "origami" itself to fit into smaller launch vehicles. Or how many parts ISS had to be built out of in space, dramatically escalating both ground engineering / production costs and in-space assembly costs (the latter costing nearly $10m per man-day). There are serious expenses to trying to compensate for a lack of space or payload capacity when you really need it.
Then there's the size of the market. As launch costs have been dropping, the number of companies looking to launch payloads has skyrocketed. The skyrocketing launch demand has been reducing average payload development costs, as designs get more reuse. Both of these trends will continue as costs continue to decline. Meanwhile, new markets will continue to open up. Space tourism has always been hindered by the absurdly high launch costs, limiting it to only the wealthiest individuals. While it will remain a "small" market for the forseeable future, it can expand by orders of magnitude with reduced launch costs. Which again makes more demand..
Lastly, there's economies of scale. It's generally recognized in the rocketry world that - at least up to a point - larger rockets get a better cost per kilogram than smaller rockets. So wherein you can launch a lot at once - multi-satellite launches, large geo launches, large interplanetary probes, fuel depots for tugs/boost stages, shielding mass for manned missions, etc - you tend to save a lot of money by going big rather than using multiple smaller launches. The caveat is that just simply going big is no guarantee of a price reduction. Just like you can make an absurdly-expensive smaller craft, you can also make an absurdly expensive large craft. And even a "moderately priced" large craft isn't generally a "win" - if you can sell payload space for $5k/kg on a 10 tonne payload rocket and for the same price per kilogram on a 100 tonne payload, the vast majority of customers will choose the former. But if you're a company like SpaceX that's been delivering cost reductions on the small scale, and you can carry it over to the large scale, it gives you the potential to take the cost reductions even further.
If you can pull it off.
"You abandoned me! You abandoned my hatred!" "I... I have cuttlefish..."
If Spacex could lift 200mT to LEO for costs that are comparable to today's heavy launches, would new uses arise?
Such as? The only unitary large-lift mission I can think of is a single-mirror super-Hubble space observatory which has its own problems -- building a one-piece very large mirror, say five metres in diameter that could survive 3G-plus during launch, vibration etc. isn't going to be easy or light. The James Webb is using folding mirror segments and will have an effective diameter of 6.5 metres when deployed and it fits in a regular launcher fairing.
We've got better at doing things in space in the past fifty years, we don't have to go back into the Jet Age to justify Big Dumb Boosters.
As an aside, large amounts of stuff needed in orbit is actually fuel for satellite manoeuvering, deep-space probes, a future manned return to the Moon etc. A remarkable amount of the mass delivered into LEO and GEO today is cheap fuel at a delivery cost of $5000/kg. What I'd like to see Musk doing is working on a robot fuel production system based on, say, Ceres or other water and carbon rich asteroids, bringing back tankers full of fuel to Earth orbit. That way he could go to Mars without having to lift a thousand tonnes of fuel up from the ground in expensive boosters.
My evidence is that there is actually, in reality, no demand for large objects in orbit
That my friend is the very definition of begging the question. Your premise assumes the conclusion.
SpaceX is a for profit business. If there were no demand or market for a heavy lift vehicle then why would they bother developing one? That's a huge expense if there is no expected ROI. I'm pretty sure they have a better feel for the market than either of us. Is it possible they are building a figurative bridge to nowhere? Maybe but that would be inconsistent with their prior behavior and economic sanity. Elon Musk has been accused of many things but stupidity has rarely been among them. It is difficult to gauge demand for very large objects in space until you have a realistic means of getting them there. Given that SLS is subject to the whims of congress and that SpaceX hasn't brought their heavy lifter to market yet why would anyone seriously plan a very large satellite today? Simple logic would dictate taking a wait and see approach. Once the lift vehicle is available then and only then should we expect to see very large objects getting designed.
SpaceX will be streaming Elon Musk's presentation live on their website.
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
As conventional fuels were in extremely short supply by late 1944, Lippisch proposed that the P.13a be powered by coal. Initially, it was proposed that a wire-mesh basket holding coal be mounted behind a nose air intake, protruding slightly into the airflow and ignited by a gas burner. Following wind-tunnel testing of the ramjet and the coal basket, modifications were incorporated to provide more efficient combustion..
The coal was to take the form of small granules instead of irregular lumps, to produce a controlled and even burn, and the basket was altered to a mesh drum revolving on a vertical axis at 60 rpm. A jet of flame from tanks of bottled gas would fire into the basket once the P.13a had reached operating speed (above 320 km/h), whether by using a rocket to assist takeoff or by being towed..
The air passing through the ramjet would take the fumes from the burning coal towards the rear where they would mix under high pressure with clean air taken from a separate intake. The resulting mixture of gas would then be directed out through a rear nozzle to provide thrust. A burner and drum were built and tested successfully in Vienna by the design team before the end of the war.
Apollo 17. A geologist on the moon did more science in, collected more data, studied more samples, in 3 days, than the MER rovers have done in several years