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91

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 expected as early as the 17th century that the atmosphere would get steadily thinner with increasing altitude, giving way to vacuum. These expectations were ...


88

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 thermal environment is a variable. If the car + payload adapter tumble, the car will spend time in the shadow of the adapter, and you get thermal cycling which will ...


86

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 pointing a torch (flashlight) with a (well focused) beam at a far target than aiming with a tiny Laser spot. For comparison, 0.6° is slightly larger than the ...


69

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 to get a very light rotor going, there is still an awful lot of force involved which has to be handled by the materials to prevent them literally tearing ...


67

According to Wikipedia, Voyager 2's launch window was a once in 175 year opportunity - the planetary alignments allowing a visit to Jupiter, Saturn, Neptune and Uranus. Adding more planets to a Grand Tour alignments would make them rarer.


67

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 pole, winch or anything else into the lower parts of the atmosphere, it would also move at about 27,500 km/h (if we ignore atmospheric drag and all other ...


63

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 enough to orbit the earth, so came back down) was in 1944. This rocket was designed to launch, fly in a specific trajectory, and land in a (relatively) specific ...


59

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 spacecraft. The actual velocity is irrelevant here, it's the same principle with every spacewalk: the ISS is moving at about 27,600 km/h, yet the astronauts do not "...


58

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 did the shape of it matter. It would never have to deal with aerodynamic drag. In fact, the descent stage was designed to buckle in the right places upon landing,...


56

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 paint and underlying aluminum from debris hits. Below is an image of that surface after all of those sites were cored out for analysis. Note that the cores are ...


56

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 airfoils including that of a helicopter rotor. So in a helicopter at 100 km altitude, your blades have to travel at orbital speed (27,000 km/h or 17,000 mph) ...


53

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 system. On earth, if you want to go anywhere, you can get there at any speed, it just takes longer. Unfortunately, that is not how it works in space, because the ...


53

I suspect the wooden sphere is a three-dimensional Helmholtz coil. There are circular groves visible filled with silicone or something similar. The groves contain the Helmholtz coils, one pair for each direction. An electrical current flowing through the coils generates the magnetic field. The Helmholtz pair of coils minimizes the nonuniformity of the field ...


53

It's simply the spotlights illuminating the ship, and shining up the bore of the engines. Notice the shadows of the vertical stabilizer from the same source. When the shuttle landing direction is determined, URS Corp. air traffic controllers in the runway control tower will communicate with Bordeaux and his team on the ground. Then two of the ...


51

There are a number of reasons why spacecraft electronics typically lag what is commercially available by several years. Radiation tolerance Electronics are very susceptible to radiation phenomenon that terrestrial electronics are largely protected from by the Earth's atmosphere and magnetic field. Common radiation-based failure mechanisms are Single-Event ...


49

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 trajectory on arrival in such a way, that the departure trajectory will be exactly as desired. And due to some rather unintuitive physics caveats, you can make it so ...


47

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 relevant to the question: errors went undetected within ground-based computer models of how small thruster firings on the spacecraft were predicted and ...


43

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 all have flat bottoms that they face into the wind to do that. If you compare the Dragon capsule from your link to a Soyuz capsule, the Orion capsule, or the ...


42

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 fasted launch velocity of any spacecraft that has left Earth (relative to Earth): After three years of construction, and several delays at the launch site, New ...


39

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 millions of dollars (or more) per year on this technology. Instead, NASA is spending half a million dollars on this technology, spread out over two or three years. ...


36

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 designed to float at 54 km from the surface, in the most active layer of the Venusian cloud system. The instrument pack had enough battery power for sixty hours of ...


35

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 the 1960s, many believed that Venus contained a lush, Earth-like environment. While there was some concept that Venus was hot, and had a high pressure, the exact ...


35

It turns out that outer space is not a perfect vacuum: there are a few hydrogen atoms per cubic centimeter. (reference) For large X, non-relativistic physics, the astronaut and spacecraft will stay close enough to each other. Once X gets small, and you approach the speed of light, these hydrogen atoms could slow down your spacecraft. Therefore, to maintain ...


34

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


33

The NASA software for the Apollo Guidance Computers is released. Further, a low-level hardware emulator running the software is available; the source for the AGC is in several released manuals. Likewise, the Apollo Landing Computer has been emulated. Current software generally isn't released due to the risks to the hardware; NASA eventually has to release ...


33

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 the shape of the first satellite, with most senior OKB-1 designers preferring a conical form since it fit well with the nose cone of the rocket. At a meeting ...


33

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. Similar to pushing a train by hand. A submarine is designed to keep water out. It wouldn't be airtight enough and would leak badly. A nuclear submarine needs LOTS of ...


33

Space is really like this (XKCD What if) In theory a plane could reach most of the way to space, but it won't be able to reach orbital speeds. Bottom line, it just isn't practical. Maybe someday a helicopter could lift a rocket up high, which would help a bit, but it really just isn't practical. Also, a balloon might just be better in any case, it can go ...


33

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 chemical rocket might have a specific impulse between about 250 and 450 seconds; therefore, the exhaust velocity is about 2500-4500 m/s. In a competitive ...


33

What are the benefits of cryosleep? Don't need as much volume/mass for living space Don't need as much volume/mass/energy for life support Don't need breathable atmosphere or airtight ship Can have the ship be at much lower temperature Travel time not limited by how long food supplies last or the passengers' lifespan If cryosleep chamber also immerses ...


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