Category Astronomy

Why can’t you take Coca-Cola into space?

We have tested Coca-Cola (and Pepsi) in space. In 1985, we flew special dispensers from the manufacturers as an experiment aboard the Space Shuttle.

Soda in space is a bit problematic. In micro-gravity, the light gas bubbles won’t rush to the top of the liquid and escape. They will stay within the liquid. This means the astronaut will consume significantly more gas drinking a soda in space than one would drinking a soda on the ground. Drinking a carbonated beverage could be like drinking a foamy slurp.

That means there will be more of a need to burp, to release that gas. That would be okay, except burping in space is unpleasant, for the same reason mentioned above for the soda. On the ground, gases and liquids naturally separate in the digestive system because the lighter gases rise above the heavier liquids. But, in micro-gravity, that doesn’t happen. When one burps in space, it is often a “wet burp” which means some liquid is expelled. It’s kind of like acid reflux.

 

Credit : Quora

Picture Credit : Google

What will happen if an astronaut fires a gun from the Moon aiming at Earth?

The .220 Swift remains the fastest commercial cartridge in the world, with a published velocity of 4,665 ft/s (1,422 m/s) and the escape velocity of the MOON is 2,400 m/s so the bullet will not leave the vicinity of the Moon and will eventually return to the surface.

And to respond to the dozen’s of people who have commented below that a rifle bullet will not work in space or on the Moon , yes it will , and actually , like a rocket it will work marginally better . A bullet carries it’s own oxygen in it’s propellant powder and does not need air to ignite !

The only ballistic (Non missile) round that would leave the moon would be one coming from a rail gun which can reach a velocity of upwards 5–6000 m/s (21,600 km hr).

If aimed very accurately which would be very difficult to do it could enter the earth’s atmosphere at a speed in excess of 40,000 km/h or 11,100 m/s .

As the projectile enters the Earth’s atmosphere it will compress the air ahead of it to a temperature of 8000–10,000ºC and melt and burn up , not striking the ground but vaporizing 15 -20 kilometers above ground maybe terminating in a loud explosion.

 

Credit : Quora

Picture Credit : Google

How do space telescopes keep their lenses clean?

They don’t get dirty.

There is nothing in the vacuum of space to collect on the mirror.

Orbital debris is a potential problem, but experience with Hubble shows that it’s not too serious. But if the mirror does get hit, it’s not something you’ll be able to clean off…it’ll be a hole the size of a quarter.

Hubble’s biggest problems with debris has been impacts to its solar panels:

But Hubble is in a moderately low orbit – because that’s as high as the crappy Space Shuttle could get it.

These days, we’d put it MUCH farther from the Earth—far from the places where debris is common.

The James Webb Space telescope isn’t even going to be orbiting the Earth—it’s going to be parked in a Sun-centered orbit at the Earth/Sun L2 point.

 

Credit : Quora

Picture Credit : Google

If an astronaut fell over a 300 ft cliff on The Moon, would the low gravity save him, and would he bounce?

It’s not the fall that kills you, it’s the sudden stop at the bottom.

Bouncing doesn’t come into it. The question is, how fast are you going when you hit something. The faster you are going, the more energy you contain when you hit the ground—energy that now tries to break bones and crush organs like tomatoes on the windscreen of a passing car.

On Earth, the general rule of thumb is that you risk serious injury from any fall higher than you are. On the moon that would have to be adjusted; lunar gravity is only 1/6th as strong, but there is no air—so you will never reach a “terminal velocity” beyond which you don’t speed up any further.

If an astronaut fell 300 feet on the moon, that’s a 91.44 meter drop at 1.633 meters per second per second acceleration (we’ll do this in metric because metric isn’t a stupid, byzantine measuring system). With no air resistance at all, our hapless astronaut will hit the ground after 10.6 seconds, at a velocity of 17.2 meters per second.

How dangerous is that? Well on Earth, to hit the ground at 17.2 meters per second (ignoring air resistance), you’d have to fall from a height of 15.2 meters, or 49.8 feet, or the roof of a five story building. Onto rock or dry sand. Does that sound like a good idea?

No. Such a drop would likely break the spacesuit and would certainly break the occupant.

 

Credit : Quora

Picture Credit : Google

How do they keep the International Space Station’s inside temperature warm?

The outside of the ISS can reach temperatures as high as 250 degrees F (121°C) on the sunny side and as low as -250 degrees F (-157°C) on the shady side. Inside the ISS are plenty of things that generate heat – such as human bodies, laptop computers, pumps, and other electrical devices. It takes a lot of work and complicated thermal control systems to remove that heat from its sources and transport it outside where it can be radiated to space.

For the parts of the ISS that do need active effort to keep warm, that is accomplished using simple electrical resistance heater pads, like the one shown in the below picture. They work on a simple premise – the thin pad has a wire running back and forth and back and forth many times within it. That wire is attached to an electrical source and electricity flows through the wire. The circuit has resistance and resistance results in heat. The wire gets warm, so the pad gets warm, and so whatever surface it is adhered to will also get warm. A thermostat will measure the temperature in that vicinity and the value of that temperature will be used to turn the electrical circuit for the heater pad on and off. There are hundreds of these pads throughout the vehicle.

It is important to use these heater pads to keep the shell of the vehicle warm, because if the temperature drops below the dew point, condensation will form on that surface. Accumulations of water can cause problems with electrical equipment and can promote the growth of microorganisms.

 

Credit : Quora

Picture Credit : Google

Is it true that travel to Mars can occur only once in every two years? If so, why is that so?

It isn’t true that travel can only occur every two years, but the conditions are far more optimal at those times, essentially making other times unconsidered.

There are different types of Earth-Mars mission trajectories. They don’t all start when Mars and Earth are close. There are multiple factors involved, including whether or not the spacecraft is to come home, whether a gravity assist from Venus is available, and the capabilities of the launch vehicle. However, for the typical one-way mission to get a probe or rover to Mars, we do indeed launch when Mars and Earth are fairly close.

Mars and Earth are at their closest to each other when they are at opposition. However, we don’t actually want to launch at this point. We want to launch before this point.

We want to use a minimum energy transfer orbit in order to use the least amount of fuel. A Hohmann transfer orbit does this. Our spacecraft starts at Earth’s orbit. A Hohmann transfer orbit uses a burn at the starting point (periapsis) that increases the aphelion of the orbit such that it occurs at the orbit of Mars. This will be 180-degrees later in the orbit.

So, our goal is to time the launch such that Mars will be at that same location when the spacecraft gets there. Since Mars is in a larger orbit, it takes longer to move the same angular distance as the Earth. That means we need Mars to be ahead of Earth when we launch our spacecraft.

We calculate the period of the orbit that our spacecraft will be in. That turns out to be about 520 days. Our spacecraft is traveling half of an orbit, so our trip will be about 260 days. Mars has an orbital period of 687 days. In 260 days, Mars will travel an angular distance of 136 degrees. That means the optimal time to launch the spacecraft is when Mars is 44 degrees (180-136) ahead of Earth in its orbit, as shown below. That means we launch the spacecraft about three months before Mars and Earth are at their closest.

 

Picture Credit : Google