77

+1 Good question! It's not actually gold, but I think this is a common misconception, so allow me to elaborate for a bit. The stuff that you see satellites covered in is not normal foil, its just the outer layer of so-called "Multi Layer Insulation" or MLI. That means that there are several layers of foil, each separated by a spacer, so that transfer ...


28

What about their design seems to make them inflate and blow off? Did they have some sort of air scoop built in? The final version did (history below). They were made of Tyvek and had a pocket/parachute built in. I can't find a great picture but this at least shows the parachute. If they didn't blow off what would the consequences be? If they ...


21

I kept wondering where this 72 km/s maximum is coming from, and I figured it out! This is the calculation: Why? Firstly, it's obvious that the Earth is traveling at 30 km/s in its orbit. But what possible directions can the asteroid hit from? The most logical approach is to hit it moving the exactly opposite direction. That means we demand an asteroid ...


17

There was a design requirement (PDF, page 30) for a "probability of no penetration" of 95% for 2 years. The Space Debris Handbook (PDF, page 137) indicates the main risk was considered to be a light leak in the aft shroud. I haven't been able to find any specifics on construction details that ensure this. Specifically, I haven't found any mention of ...


12

Main problems Would be cost-effective only for reusable craft, mostly hypersonic spaceplanes (see NASP). Active cooling may fail spectacularly => Mission loss. It is hard to achieve required number of cycles before refurbishment due to thermal stress. Too heavy! -> Cannot compete with ablative/heat sink TPS for non-reusable craft. Timeline for Active ...


12

Astronaut spacesuits use gold (thin layer) Gold coating protects eyes from harmful sunlight Gold is also used by NASA in the construction of spacesuits. Because of its excellent ability to reflect infrared light while letting in visible light, astronauts’ visors have a thin layer of gold on them to protect their eyes from unfiltered sunlight. Satellites ...


9

The Marmac 300 barge, which was modified into ASDS JRTI is made out of steel. There has been a lot of modelling and debate in the NasaSpaceflight.com forums trying to estimate how thick. Current thinking seems to come out around 25-35mm (1 inch to a bit thicker) steel. The heat load of a landing stage is not really that high. A single Merlin 1D at 70% ...


8

EVA suits need to meet the following requirements: A stable internal pressure. This can be less than earth's atmosphere, as there is usually no need for the space suit to carry nitrogen (which comprises about 78% of earth's atmosphere and is not used by the body). Lower pressure allows for greater mobility, but requires the suit occupant to breathe pure ...


6

According to the American Meteor Society, meteorites usually hit the Earth's atmosphere going around 160,000 MPH. Meteors enter the atmosphere at speeds ranging from 11 km/sec (25,000 mph), to 72 km/sec (160,000 mph!)... The 70~ish top figure is also repeated in this answers.com answer. Why such a big range, between 25k and 160k MPH? The wide range ...


4

Is radiation more dangerous to some parts of the body than to others? Yes. Health physics uses tissue weighting factors as a way of factoring in the relative sensitivity of different tissue types. Is partial shielding practical? For the most part, no. Some of the highly sensitive tissues are the bone marrow, lungs, and intestines, meaning an effective ...


2

To my knowledge the only in-space study was that on Apollo 17, when pocket mice were flown in a closed container in the command module. (Note this means that the mice never made it to the moon.) Four of the five mice survived. One cage was left empty. On their return, the courageous Mousetronauts were killed, dissected and examined for after effects. The ...


2

Radiation on Mars is an issue, Mars has no global magnetic field comparable to Earth's geomagnetic field. Combined with a thin atmosphere, this permits a significant amount of ionizing radiation to reach the Martian surface. Readings by the Curiosity rover during its first 300 days on Mars were between 200 and 250 micro-Gray per day.


1

Clearly, the answer has to be a probability distribution. The actual distribution would necessarily "encode" the past history of the galaxy, neighboring galaxies, etc. Since a fast-moving object has a longer trajectory, it has a greater probability of hitting something. Consequently, the faster-moving, longer-path objects will collide sooner and will be ...


1

My understanding from basic physics is that when you calculate the requirements for escape velocity from a body's gravitational pull, the math is also able to point out the maximum accumulated velocity possible due to the pull of that gravity toward an object. In other words, while escape velocity calculates what is necessarily to counteract the body's ...


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