Soldato
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For take-off, yes. But what does that have to with landing on Mars?
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** The Official Space Flight Thread - The Space Station and Beyond **
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The booster doesn't land on Mars.
Only the upper Starship does with six engines. The big booster only gets the Starship up to space.
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Soldato
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Are you being deliberatly obtuse?
Soldato
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I wonder if it will be like the Moon version with some engines 3/4 of the way up the body so it won't have to use the main engines at high throttles. Its going to be a long time before a Starship heads to Mars, let alone attempts to come back. Huge technological barriers to solve and a lot of infrastructure to ship there to make the fuel, refrigerate it and keep it in liquid form. I'll be amazed if it happens in the next 20 years.
As long as you have sufficient power, liquifying gases can be done.
Storage of cryogenic liquids is pretty good. We have dewars with such a low boil off rate that it takes months for the contents to warm up. Add in a system to recycle the boil off and it can be kept indefinitely liquid as long as you have power.
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Soldato
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Yes but all that power and infrastructure has to be shipped to Mars. You have do it in a place where there is lots of ice, that means the poles, that means solar is useless, its pretty much useless anyway as a reliable energy source due to dust storms that can last weeks or even months but at the poles it really is useless. So lots of RTGs to ship there along with machinery to mine the ice, purify it, lots of power for the electrolysis to get your hydrogen and oxygen, refrigerate it and keep it as a liquid for use. Then lots more energy for the Sabatier process when you have the CO2 which is there and makes up most of the atmosphere but the atmosphere is only 0.095psi. The hurdles are HUGE, we are decades away from being able to make enough fuel to fill a Starship for the return journey. Elon makes it sound so easy, its anything but easy and the fact he says they'll do it with solar shows he is either lying or deluded. I think he's lying because he likes to sell dreams but they have to be taken with a lorry full of salt.
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Soldato
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Another subscriber to the Common Sense Skeptic I see...
Yep. Elon is a master at making things sound so easy. Making CH4 might be doable in principle and on Earth it is if you have the power and infrastructure but Mars isn't Earth. Everything you need to have to ship there. If anything breaks replacement parts are a minimum of 7 month away but could be years away depending on where the 2 plants are in their orbits. And you have to land all these Starships next to each other, yes SpaceX can land a booster on a barge or landing pad on Earth but we have an amazing GPS satellite constellation they use to know where they are in space and time, there is no such thing around Mars. Its a pipe dream atm.
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A good write-up on the failure of the recent Starship launch.
TLDR version.
A Starship post-mortem: Why the giant rocket failed and why it's Elon Musk's fault
On Thursday, SpaceX launched its first full version of the “Starship” rocket from a pad on the coast near South Padre Island, Texas. Four minutes into the flight the rocket was deliberately destroyed at an altitude of about 35 km, with debris raining...
www.dailykos.com
TLDR version.
- The no-clamps slow throttle-up meant Starship stayed on the pad for a long time, throwing up concrete, rock, and sand all directions, damaging the pad, nearby facilities, and Starship itself.
- By the time it left the pad, that debris had already destroyed three of Starship’s engines and likely damaged valves and systems that would lead to additional engine failures as well as an incorrect fuel mixture.
- Starship was slow to reach every point in the flight plan, suggesting that other engines were not able to throttle up to compensate for the lost engines.
- At what should have been stage separation, either software errors or more smashed hardware kept the main booster firing long after it should have shut down.
- The result was an uncontrolled spin that required Starship to be destroyed.
- A flame-diverter or flame trench to redirect the blast from the booster’s engines
- A water deluge system to dump a massive amount of water around the launch tower during liftoff
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Soldato
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Break things fast.
I guess they have tested to literal destruction any concept of not having a flame diverter.
I guess they have tested to literal destruction any concept of not having a flame diverter.
And here I was thinking that the aliens would have it all built in preparation for our arrival. I guess we need relatively cheap rockets with a fast turn around to enable quick launches. Since it sounds like lots of trips will be necessary to get equipment there.
You’ve also written a lot of stuff unrelated to my post, I’m guessing you want my opinion or something, so let’s have a look.
what stopping them from shippings lots of RTGs and the machinery they need for mining?
Finally an actual huge (is this your word of the day or something?) problem. You could have skipped all the other preamble and just got to this.
We have pumps that work with low pressures but generally require incredibly clean fluid to function. Then there is collecting the volume required for creating enough fuel. Especially since it also has a high expansion ratio (600 to 1). Not sure how or if they can overcome it.
No seriously is this your word of the day or something?
Also how do you quantify a huge problem vs a big problem or a large problem?
Or do you like you hyperbolic language because you want a certain pessimistic tone to your post?
Maybe there are impossible challenges that simply cannot be overcome with our current technology but you haven’t listed or detailed them in your post.
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Getting the nuclear fuel required for RTG’s is not easy, cheap or quick, and will a substantial problem. I also feel getting water from the poles to the launch site will be a massive problem.
The issues are immense. Huge, almost.
I never claimed it was easy cheap or quick to get fuel for RTG. Not sure where you got that idea from.
But since you’ve brought it up why don’t you go into more details about how RTG fuel is acquired?
Is immense todays word of the day?
It also goes on to blame Musk 100% for the failure due to his insistence on not having:
still chicken and egg if the raptors weren't firing up , the launch system or mission control could have aborted, post T=0
hadn't appreciated it's telemetry was initially (mid21) unencrypted so people could see data - would be a prestigious cybertarget.
Cybersecurity experts have also expressed concern about cyberattacks against NASA and its private contractors that have been traced to international actors in countries that are not particularly friendly toward the United States, such as China and Romania. In one 2012 case, a laptop being used by a NASA employee was stolen. The laptop contained commands for the International Space Station, although there is no evidence that unauthorized parties have actually attempted to use the information to control the International Space Station.
still chicken and egg if the raptors weren't firing up , the launch system or mission control could have aborted, post T=0
hadn't appreciated it's telemetry was initially (mid21) unencrypted so people could see data - would be a prestigious cybertarget.
Cybersecurity experts have also expressed concern about cyberattacks against NASA and its private contractors that have been traced to international actors in countries that are not particularly friendly toward the United States, such as China and Romania. In one 2012 case, a laptop being used by a NASA employee was stolen. The laptop contained commands for the International Space Station, although there is no evidence that unauthorized parties have actually attempted to use the information to control the International Space Station.
Soldato
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You think RTGs are 2 a penny? NASA only put them on their last 2 rovers, there is a reason for that. Before that it was solar but solar is a major problem on Mars and the dust storms killed the rovers. RTGs are rare and expensive. They aren't going to be made for a private space company when NASA have their own missions requiring them? The current RTG design makes 110w, there is the GPHS-RTG which makes 300w but that needs 7.8kg of Plutonium 238, not exactly a common element. You'd need dozens of those to generator the power required to make the fuel for a Starship and they cost between $65-90m each.
Elon has said he'd use solar but solar won't work at the poles where the ice is.
Yes it is a huge. The whole thing is a huge.
Nothing is impossible. With enough money just about anything can be done but where is the commercial revenue coming from to justify the investment in Mars? The Moon has elements we could use like Helium-3 and is only 3 days away, what does Mars have? No investors are going to give $b to satisfy Elon's dream if there is no pay day at the end of it.
Re RTG's, IIRC they can be made easier/cheaper than the ones Nasa have, but there is a definite mass/reliability cost.
I seem to remember Russia made something like a couple of thousand of them, but they were used to do things like provide power to unmanned earth bound installations such as light houses, not survive launch into space, then the conditions of space and re-entry.
It's still not a particularly practical thing for something that is going to need a lot of power as the whole basis of the RTG is that it's a low output, longterm source, and you really don't want to be putting too much of that material on any one rocket.
I seem to remember Russia made something like a couple of thousand of them, but they were used to do things like provide power to unmanned earth bound installations such as light houses, not survive launch into space, then the conditions of space and re-entry.
It's still not a particularly practical thing for something that is going to need a lot of power as the whole basis of the RTG is that it's a low output, longterm source, and you really don't want to be putting too much of that material on any one rocket.
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I can't imagine the FAA giving a licence for any rocket carrying multiple RTGs for the simple reason that if anything happened you could have a lot of plutonium raining down over the gulf of Mexico.
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Apparently the RTG from Appolo 13 re-entered the atmosphere and as far as NASA can tell the container survived intact and hasn't leaked any radiation.