Another batch of questions addressed with off the cuff answers, and visuals provided by Orion, who is hopefully learning something from watching these things while earning some money from editing.
As usual, the questions are taken from supporters of my Patreon – I still have a great backlog of questions to cover.
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Two chances to reference Bond movies (the Quantum of Solace hotel and, more ostensibly, the diamond fabrication technque re: Diamonds are forever), and we are left without Mr. Manley's impersonation of Sean Connery? Shame, shame, shame… xD Greetings from San Jose, anyway!
Regret 15:15 you lost me.
More on the first question, there is a JPL tool called "SPICE" that is used to do the number crunching. its a FORTRAN program. There's also a MATLAB version (MICE), a C version (CSPICE), and an unofficial Python binding (SpacePy i think). Yes, it is free software. No, it is not easy to learn.
The fun fact about vapour pressure is that it is agnostic of whatever other molecules are in the air. At room temperature, water will tend to evaporate until there is about 2 kPa of water vapour pressure in the atmosphere – whether that's pure water because there was only vacuum, or 200 kPa of 1% water.
This also means that in order to have a planet with a liquid but no gaseous atmosphere, you'd need to find a liquid that has a vapour pressure of zero – and apparently glycerin and mercury are very close, but you'd still have the faintest whiff of an atmosphere.
It should be pointed out that most nuclear waste is actually not waste at all, but unspent fuel "contaminated" with radionuclides that don't play well with legacy reactor designs. However, there are many other kinds of reactor (eg, fast & thermal breeder reactors) that have much better fuel economy, some of which will happily consume nuclear "waste" after a bit of processing.
So no matter how you look at it, launching nuclear waste into space is a totally counterproductive idea.
Great answers to great questions!
At 12:00, noteworthy for being used as a filming location in “Quantum of Solace”.
So that Lithium-Fluorine-Hydrogen concept could be used for an “un-jammable” missile?
We have those type of deserts in… China, far west. They are really dry and high up the mountains chains.
Now there are a reason why 95% of Chinas populous lives at the east coast, go figure
Why are you disparaging my asparagus staging?
15:23 gallium is much better cos it has boiling point at 2673 K and melting point at 303 K, and has 1 Pa pressure at 1310 K, so it will have pressure less than 1 Pa over liquid over more than 1000 K temperature range, unlike mercury with only 81 K range.
You can actually make your own artificial dwarf planet out of gallium, if you launch small amount of it at heliocentric orbit lower than earth orbit. Cos it will be in perfect hydrostatic equilibrium, as the definition says. And it will even last longer than human life.
Despite the economic downturn,I'm so happy☺️. I have been earning $ 60,000 returns from my $7,000 investment every 13days.
Regarding the CO2 scrubber square peg, round hole.. I understand re-fitting and redesign was not really an option but I would have thought they'd send them up with a "pre made" bag device. It could have been folded up in an envelope and saved a ton of time making one in the middle of a disaster. That way they could sign off they "fixed" the problem. I was surprised they decided to go with the do it yourself in space approach.
I do heating and cooling for work, we measure a few things like duct pressure and vacuum pressure in In of HG
Hello Scott. I am trying to find a copy of the Lithium-Fluorine-Hydrogen Propellant Investigation report and I can't get it off the NASA website. How did you get a copy?
@scottmanley >>> 👍👍
I wonder if we’ll someday see starship ferrying LH2 in a starship tanker to LEO. 1000 cubic meters cargo volume would carry about 70tons LH2. Unused mass capability could carry LOX to use the full payload capacity.
The idea of an earth departure on LH2 with higher exhaust velocity and a return on methane made on mars seems viable so long as the equipment isn’t too heavy.
7:48 Wasn't doing that what kicked off Space 1999??
another video with ruzzian propoganda in it. why dont you just move to ruzzia, they might even give you a free gun
Didn’t they use that hotel in Quantum of Solace?
Seems like if you want a high, inhospitable land to do Mars experiments on, then the Tibet plateau is the place to go. I know China is going to be difficult about that, so maybe that's why you didn't mention it, but that's probably the most mars-like environment on earth where people do in fact live.
Great questions and answers!
Thanks for mentioning mercury inches. My Mum's had a barometer in the hall that is probably at least 70 years old if not 80 or more and still works fine, so I got used to seeing the pressure between 28 and 30. I think the lowest I ever saw it was just above or below 28 and the highest just over 30.1 It's usually between 28.5 and 29.5 (I don't know what altitude it was calibrated for – it might have that written on it).
I don't think we learnt about pressure in mercury inches at school or uni – only millibars or Pascal, which are easier to do maths with! It would have been nice to know the connection with mercury inches (or cm) and Pascal, and how the old barometers worked.
I do it in Kerbal all the time 😃
"What are your opinions on using the moon/space to dispose of nuclear waste." Do you want Space:1999? Because that's how you get Space:1999.
"Appretnly, there's a lot of ways you guys can send me messages!" – says flustered Scott, as owls keep circling his house, and envelopes start bursting out of the fireplace.
Would an orbital 'tug' make sense for transiting between orbits, to reduce the complexity of the ground-to-orbit craft? It seems to me that you would want something like that rather than expecting the crew capsules do everything unassisted. Does orbital mechanics and/or fueling costs make this impractical?
The topic of sending used nuclear fuel (aka high-level waste) to space, or into the sun, or some variation on the same theme, seem to be popping up quite regularly. It's very disappointing to see it here as well. But basically I think it's predicated on this impression people have that nuclear waste is this intolerable burden on future generations, qualitatively unlike any other waste human activity might generate.
The reality is that nuclear waste must be kept away from the environment until the most (radiologically) volatile isotopes have decayed away, after which it is a superb resource for Uranium and Plutonium that can be fed back into reactors.
The cut-off point for which isotopes to worry about is Strontium-90 (Sr-90) and Caesium-137 (Cs-137), both of which have a half-life of around 30 years. There is a simple rule of thumb that after 10 half-lives, the radioactivity will have decayed away to nearly nothing (technically one 1024th). So that's around 300 years in this case. You can also decide you want it to decay to one millionth, in which case you have to wait 600 years instead. Same difference — we have built cathedrals that took longer to complete, so to think that we can't protect something for this duration is a bit silly.
The next isotope down the list of stuff you find in nuclear waste (used nuclear fuel) is Plutonium-239, with a half-life of 24,500 years. Ten times this is a quarter million years, and this is the "back of an envelope" version of the calculation that leads to why it is often said that nuclear waste must be protected for hundreds of thousands of years. In reality, this is false. They are applying an extreme version of the "precautionary principle", since Plutonium doesn't exist naturally on Earth, life of Earth has not evolved around it. Therefore, the thinking goes, any leakage of Plutonium into the environment, no matter how small, slow or unlikely, is unacceptable. The reality is that the radioactivity from Pu-239 is quite moderate, and the isotope can be handled without shielding.
The repositories for used nuclear fuel attract a lot of attention and controversy. But in reality, they are basically the same as permanent repositories for chemical waste, including elemental substances like Arsenic, Cadmium and Mercury. These attract hardly any criticism, yet they need to protect their contents literally for eternity, precisely because these things are not radioactive (i.e. they don't decay).
My own view, however, is that it is still a mistake to put used nuclear fuel in geological storage. Instead, we should just wait the 300 years until the hot stuff has gone away, then reprocess it and put it back into future reactors. Alternatively, it can be reprocessed immediately, at greater expense but with quicker rewards. Remember, 95 to 99 % of the nuclear energy is still present in nuclear fuel as it leaves the reactor — it's like putting a bar of chocolate in your mouth, licking on it for three seconds, and then throwing it away.
The only thing we achieve by putting it in the ground is making an artifiial Uranium and Plutonium deposit for future generations, but making it unneccesarily difficult to get to.
I think a good plot device for use in stories would be one or more cyclers that grow to be space colonies in their own right.
My dad works with pacemakers.
The plutonium ones were actually pretty good according to him and lasted for AGES.
Biggest problem was you'd need to remove the pacemaker prior to the burial.
Worst space project? I still think STS set space flight back 30 years. There were so many early concepts that showed promise which could have lead the way to full reuse. In the end NASA was forced to pick (and stay with for far too long) the quick and dirty option because it would have filled a perceived military role but had no chance of making any meaningful technological leaps.
Why was SLS's TWR so high compared to Saturn V? Is that just because future iterations will be heavier with the larger 2nd stage? Or is it more efficient overall? Or perhaps adding more fuel would make the TWR too low after it ditches the SRBs?
Wasn't that hotel in a James Bond movie?
Why does a nuclear diamond battery need to be packaged in a vintage 22 pin dip chip? Two pins to handle the microwatt of power… And 20 pins for a centronics parallel style interface to detect whether your chip is about to have a Homer Simpson core meltdown?
How is it that to see big bang you just point the teleskop anywhere¿
I would just like to point out that the Apollo 13 tank explosion was more a failure of paperwork than design. The 1965 decision to have the systems work on 28 volts and 65 volts both, was mussed by the O2 tank makers. The 1968 incident of dropping O2 tank #2 by two inches and damaging an internal tube used for filling and draining LOX was missed initially and later discovered in a 1970 wet test. Unable to drain the LOX post test, it was decided to leave the heaters on and boil off the LOX to empty the tank. The 65 volts blasting the 28 volt thermostat welded it closed loop and the resulting temps cracked some wire insulation on the heaters. An incredible chain of accident events… and I believe the astronaut that signed off on the heater evacuation process was Lovell himself. This same hardware had flown on 5 successful manned flights. The odds of all this happening is astronomical, yet it did. The design was sound for the acceptable risks. The errors were clerical, procedural and the acceptance of the unknown risks of an alternate non standard procedural fix. Then again, it was 1968 and we had a goal to land on the moon in 1.5 years.
Just read a really cool article in Nature about AT2022cmc, a tidal disruption event in which a supermassive black hole swallowed a star 8.5 billion light years away and the resulting relativistic jet of energy was pointed close enough to Earth that it could be studied by multiple telescopes, including Hubble. So much information in the article, but the thing that really caught my eye was something called Doppler boosting. It would be great if Scott talked about this in a future video.
Another reason the Buran program was cancelled was because the US never built a 'Star Wars' orbital missile defence system put in place by the shuttle; Buran was built, in part, to answer the proposed US "Space Shield" Star Wars system which would have relied on the shuttle to build it. If the Soviets wanted a "Star Warski" system, in answer to the US system, they, too, needed a shuttle. When it proved impractical for the US to build huge orbital laser battle stations, one of the prime drivers of the Buran program vanished.