ARS

How does space telescope clean the mirror and maintained? Is there any maintenance schedule for it? Since Space Shuttle is already retired and it's unlikely Soyuz is equipped for such task

What's the highest possible altitude of hydrogen-filled zeppelin (not operational altitude, the highest altitude attainable) if we rig the zeppelin with every possible method to ascend (weight reduction, blow the ballast, remove any non essential subsystems even if it only left the zeppelin with just gas envelope filled with hydrogen and minimal control suite). Is it possible to reach the edge of atmosphere? (Assuming the thing could survive the trip through the atmospheric layers)

Human embryos have a tail that measures about one-sixth of the size of the embryo itself. As the embryo develops into a fetus, the tail is absorbed by the growing body. Infrequently, a child is born with a "soft tail", which contains no vertebrae, but only blood vessels, muscles, and nerves, but this is regarded as an abnormality rather than a vestigial true tail, even when such an appendage is located where the tail would be expected. Fewer than 40 cases have been reported of infants with "true tails" containing the caudal vertebrae, a result of atavism. Humans have a "tail bone" (the coccyx) attached to the pelvis; it comprises fused vertebrae, usually four, at the bottom of the vertebral column. It does not normally protrude externally - humans are an acaudal species. Also, the term "prehensile tail" is only used exclusively for monkeys and any other tree-climber mammals that uses their tail explicitly to grasp tree branches to aid mobility. Different animals have different function of tails, some are significant for themselves (ex. Birds uses their tail like elevator for flight controls, cats for balance, fishes for locomotion), others are less important individually but benefit more for groups (ex. Deer uses their tail for signaling others). If one goes for tailed humanoid in their fiction, it's either: 1. Different species than humans, but live like humans, though their culture adapted for their physiology 2. Biological experiment gone wrong 3. Evolved from corresponding animal, with their tail merely a vestigial organ 4. Aliens (this last one tend to have tails that's strong enough to rip humans apart)

If humanoids have tails, their culture and lifestyle is obviously already different than normal humans. Their day-to-day affair is already adapted for their physiology. An example of this could be seen on Utawarerumono series, where your ordinary human ends up in a world full of humanoids with animal traits. When he attempted to use common sense (including pulling tails out of curiosity), it backfired on him because the culture, tradition, manners and even the clothing is different than our world Also:

That's awfully close to what we have now, with the exception of: 1. Hot air balloon as a personal flying device. We commonly use cars now 2. Electric clothes concept exists, but not for changing colors but for heating (although it does change color, if you see it from thermal imaging camera) 3. LCD is actually starting to get replaced with LED (but still, pretty close approximation of what 20th century tech looks like) 4. We still use money, and it's still driving the economy

Is there any reason why submarines almost always colored black? (Or at least the portion that'll be visible when it surfaces since the bottom portion that's underwater will also almost always red) If there's no particular reason, especially that impacts it's combat performance or stealth (as long as it stays underwater), does it mean it's fine to paint the submarine with dazzle camo or for the extreme, garish color like pink?

Is it possible to reduce the G-force during reentry by making the reentry capsule outfitted with liquid breathing immersion module? So the crew is immersed in liquid to dampen the G-force, while still allowing them to breathe

Planet: Triptych: An ocean planet with little to no landmasses, save for sparse island on it's surface. The main feature is the large area of shallow waters around it's islands, and deep ocean and deep sea surface features such as underwater mountains, cracks, trenches, volcanoes, etc. The atmosphere is full of thick, surface-obscuring clouds making visual observation of planetary features from orbit difficult. In addition, thick fog perpetually blanket the sea, making an attempt to find the island difficult. Kerbol shines dimly on this planet

Well you find it out, huh? Yeah, I'm writing a submarine science fiction

What's the advantage and disadvantage between SLBM missile tubes behind the conning tower versus in front of conning tower on submarines?

Firing bullet underwater makes the bullet travel less due to underwater drag and significantly reduces its effective range. If say, there are 2 people swimming underwater, and they are at sufficient distance, is it possible for people to A fire a (non-underwater designed) bullet into person B, in such a distance that the bullet simply slows to a crawl just inches away from people B's face that the people B can clearly see the bullet before it drops down and sink underwater?

Probably the F-15 STOL/MTD project, which eventually produces the IFCS system

Could you fly an aircraft with twin-tail twin-engine design (such as F-15 or Su-35) using only one tail (with the other one ripped off) and compensating by using rolling+pitching in place of yawing while disabling the remaining vertical stabilizer?

On MAZ-based transporter-erector launcher vehicles, what's the purpose of the that secondary cabin separated from the driver's cabin? Does it serve any functional purpose or just for passengers? What about it's civillian version?

No, not the snorkeling equipment. The wooden log that's usually carried on the back of the tank that traced back as far as the British Mark series'

On tanks (particularly Soviet tanks of WW-2 era), why they're carrying log on the back of the tank? What's it's purpose?

Could nuclear explosion irradiate the ever-changing snowfield? For example, if we drop a nuclear bomb (several if need be) into a snowfield with a constant blizzard, after the resulting explosions, does the ground zero is still irradiated and dangerous after several years, even after the blizzard has buried the irradiated ice layer deep beneath several meters of ice? (Ignoring the radiation that's spread by blizzard)

You can ignite the upper stage after liftoff. The idea of ELV is staging anyway

Could we launch a payload to orbit using V2 rockets arranged in ELV stack? Imagine a V2 rocket, now strap several of them for the 1st stage, then make smaller 2nd stage from the same rocket, then the smaller 3rd stage, and so on... Assuming the payload's mass is around current-day range of space payload, is this possible?

During Space Shuttle Columbia disaster, some of the debris that's found is secured behind police line, and some of these debris site has a biohazard and/or ionizing radiation warnings. Is there a part of Columbia (or space shuttle) that does have biological or ionizing radiation hazard? Because when a space shuttle lands on the runway, the recovery crew and people flocks to it like there's no problem. Is it possible that those hazardous material was released when Columbia was destroyed during reentry?

Small fireworks rockets are basically solid fuel rockets, like a drastically downscaled version of Space Shuttle's SRBs (Only much less sophisticated). If a civillian pick Space Shuttle's SRBs as reference and try to upscale the size of regular fireworks rocket into SRB size, at which point the size of upsized firework rocket becomes illegal to own by civillian and no longer classified as fireworks and start to classified as actual rockets? (Because when it comes to firework rockets, the tiny ones that fits into your hand and the one attached to external tank is basically similar in operating principle: burn all propellant until there's nothing left)

Thanks! now that clears something up. I just getting some school project that involves measuring absolute air humidity, which makes me confused since I'm not familiar with this matter before before

No, I just want to know what the numbers represents

So... I had a few questions. I found this formula for converting the relative humidity into absolute humidity. The problem is, it only shows the T (temperature), and rh (relative humidity). What's the number represents for? Is it constants? Can anyone explain? source: https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/

Weather condition plays a vital role in aviation where it determines the flight of aircraft, whether it's safe to fly or not. What about spaceflight? Does the weather plays a vital role too? Especially during the ascent phase (even if it's brief). What's the weather parameters that must be checked before declaring it's safe for launch? I am particularly interested with space shuttles, since it's arrangement and assembly is different than regular rockets (being a plane strapped to giant fuel tanks with strap-on boosters instead of towers of stacked fuel tanks and engines of regular rockets)