93 votes

How did people know how to build the first space ship?

This is a very broad question, but I'll take a stab at it. It was understood that gravity pulled the Earth into a spherical shape, with dense solids and liquids below less-dense gases, and it was ...
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93 votes
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Why do exploration spacecraft like Voyager 1 and 2 go through the asteroid belt, and not over or below it?

First, space is absolutely gigantic; the chance of either of the Voyagers, or ay other outer-planet mission, hitting an asteroid was infinitesimal. Second, the asteroid belt itself isn't really ...
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92 votes
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Can I drive Elon Musk's Tesla after it's been in space for 100 Years?

Making a car run when it's been stored on Earth for 10 years can be a challenge. Storing it in space makes things worse. All lubricants will have evaporated. Cold welding is a possibility. The ...
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  • 121k
86 votes
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How was New Horizons able to direct data so precisely back to Earth?

The high gain antenna of New Horizon as an opening angle of its beam of about 0.6°. That means, it has to be pointed at Earth with an error margin of 0.3°. As a practical example, this is more like ...
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  • 12.8k
72 votes

Why do we not fly to space with helicopters? What are the practical altitude limits?

A 25m diameter rotor has a perimeter of around 78 meters. At that size, at 500rpm, the rotor tips would be going in excess of 1,400mph. At those kind of speeds, even though it doesn't take much power ...
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67 votes

Why can't they just drop a solar winch down from a shuttle and have planes fly up and clip things on?

Because space isn't about going high; it's about going fast! For example, in a 400 km orbit (like ISS) you need a speed of about 27,500 km/h or 7.66 km per second. So if you would extend a ...
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  • 12.2k
63 votes

How did people know how to build the first space ship?

One important note is that rocketry predates space travel - by a lot. The V-2 rocket christened "MW 18014", the very first suborbital flight, (meaning the rocket flew to space, but didn't go fast ...
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  • 551
62 votes
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Why is there a large wooden ball on Mariner 3's magnetometer?

I suspect the wooden sphere is a three-dimensional Helmholtz coil. A Helmholtz coil is a pair of circular coils, the radius of the coils should be equal to the distance of them. There is a coil pair ...
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  • 46.6k
61 votes
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Why does the ascent stage of Apollo 11's lunar module look like it's made of paper?

Like everything else, the ascent and descent stages were built to be as light as possible. But because they knew they would operate only in a vacuum, many things really didn't need to be sturdy, nor ...
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  • 20.8k
60 votes
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Why haven't more spacecraft/satellites been hit by debris?

They are hit all the time. It just hasn't been critical. So far. Looking at the outside portion of the Hubble WFPC2 camera after it was returned, I saw a huge number of large and small pits in the ...
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  • 57.6k
60 votes

Why do exploration spacecraft like Voyager 1 and 2 go through the asteroid belt, and not over or below it?

A Keplerian trajectory in the Solar system essentially needs to be in a plane defined by three points: the location of the Sun, the location you're starting from, and the point your target will be at ...
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  • 1,898
59 votes
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Assuming a spacecraft is traveling in a constant rate and our Astronaut will exit it to a space walk, will she be "left behind" by the spacecraft?

As long as neither spacecraft nor the astronaut are accelerating or decelerating, the relative speed of the spacecraft and the astronaut remains the same. So the astronaut will hover near the ...
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  • 12.2k
58 votes

Why was Venus rather than Mars targeted for the first interplanetary landings?

The reason is delta-v, which is a crucial concept in Spaceflight. It means change in velocity, and is the primary 'currency' that space mission have to expend in order to reach places in the solar ...
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57 votes

Why do we not fly to space with helicopters? What are the practical altitude limits?

At 100 km altitude, you get to the Karman line. This is the altitude where you have to fly at orbital speed to get sufficient lift. This definition is based on the lift equation, which applies to all ...
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  • 121k
54 votes
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If a spaceship ran out of fuel somewhere in space between Earth and Mars, does it slowly drift off to the Sun?

What you're missing is some combination of the following: objects launched from Earth orbit are still in orbit around the Sun, objects in orbit don't need fuel to stay in orbit. All the planets ...
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  • 1,754
50 votes
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How does a space probe maintain its trajectory while passing through the extreme gravitational field of the gas giants of our solar system?

The trajectory was not only "unhindered" - it was enhanced! Knowing mass of the planet you can calculate very precisely how the trajectory of a probe flying by will be affected. You modify the ...
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  • 52.6k
49 votes

Why wasn't the Mars Climate Orbiter's fatal error caught prior to launch?

NASA formed a board to investigate the loss of the spacecraft and reached some high level conclusions. The board cited a number of contributing factors, which I have filtered to include the ones most ...
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  • 18.9k
47 votes
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When will we send floating probes to Venus?

When will we send? We already did. In 1985 and 1986 the Soviet Union sent two Vega probes to Venus. Both included a robotic balloon (usually called aerobots). The two balloon aerobots were ...
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  • 920
46 votes

What are the chances that a spacecraft is hit by space junk?

Heh. So it turns out, figuring out the answer to this is precisely what I do for a living. The glib answer: it depends. It depends on how big an object you are worried about hitting. Are you worried ...
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  • 16.8k
44 votes
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Why are spaceship capsules frustum shaped?

The capsules designed to reenter the atmosphere have to slow down from about 8 km/s to zero by the time they get to the ground. They actually don't use the part that looks like a cone to do that. They ...
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  • 20.8k
43 votes
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What is the fastest speed ever reached in space travel as measured from the point in space from which it was launched to its current/final position?

Velocity relative to what? There's no central universal point to measure velocity at, so your answer is likely going to change based on your frame of reference. New Horizons did indeed have the ...
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  • 8,717
41 votes

If the Earth spun clockwise, how would that affect Space Exploration?

Primarily, locations of spaceports would change. California, not Florida would host the NASA's main launch site. Russia would be in slightly better position, able to send rockets over the Black Sea, ...
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  • 52.6k
40 votes
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Could a complex system of reaction wheels be used to propel a spacecraft?

Previously posted comments are correct: in free space (assumed free of any other bodies' gravity fields) there is no way to convert the reaction wheels' angular motion to translational motion. There ...
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  • 17.9k
39 votes
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Why were early Soviet spacecraft spherical?

From this pdf (Reconsidering Sputnik: Forty Years Since the Soviet Satellite) at NASA.gov referring to Sergei Korolev, the lead rocket engineer for the Sputnik project: There were many debates on ...
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  • 7,084
39 votes
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Puzzler - which spacecraft(s) incorporated real wood structural elements?

Rangers 3, 4, and 5 each had a seismometer encased in balsa wood to limit the impact loads.
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  • 57.6k
37 votes

Why was Venus rather than Mars targeted for the first interplanetary landings?

We didn't know how hostile Venus's surface was, until we had landed there. The atmosphere of Venus makes it easier to land there than Mars. From Wikipedia, we learn: Before radio observations in ...
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  • 118k
37 votes
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Repurposing a nuclear submarine for space travel

NO A rocket can lift a few tons. A submarine weight thousands of tons. Propel itself in space: if you add an rocket or ion engine it could. But it's WAAAAY too heavy for any of theses to work. ...
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  • 12.2k
37 votes

What are the benefits of cryosleep?

NASA is working on a so-called 'Cryosleep Chamber', but why do they need it so badly? NASA does not "need it so badly". If it did "need it so badly", NASA would be spending tens to hundreds of ...
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  • 64.6k
37 votes

Is there any way that real stars would move like they do in the classic Windows 3.x screensaver if traveling through space at extreme speed?

I do disagree with the other answers, not on the result, but on the reason. You don't need to go faster than the speed of light to pass through multiple stars in a few seconds. Putting aside the ...
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  • 471
36 votes
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Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?

The main engineering challenge in implementing your proposal is that in order to be competitive with a chemical rocket engine, the grinding wheel must rotate at an extremely high velocity. A typical ...
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