# Tag Info

55

Your assumptions are incorrect. A space ship (once it has escaped Earth) will also continue travelling - in fact it will only need fuel to change its trajectory and velocity outwith gravitational effects from other bodies. You will need sufficient fuel or power for life support, if you have a crewed ship, and a reserve of fuel to manoeuvre at your ...

53

First off, large life-ending asteroid impacts are very rare as there aren't many of them out there and we've found almost all of them: Looking at the 'continent' and 'global catastrophe' areas of shading on the right, the percentage discovered (blue line and numbers on the right hand vertical scale) is 80+%. This may not sound good, but if you look at the '...

41

The United States (along with Russia, China, Japan, India, and most other space-faring nations) did not sign (or in some cases, ratify) the Moon Treaty, and so companies that are registered in any of these countries are also not bound by it. So, that treaty is essentially pointless for anyone who actually has the ability to get to the moon in the first ...

34

There are three factors which contribute to the difference in “apparent crateredness” between Earth and Mars. By far the most significant is ongoing erosion from weather. In Mars’ thin atmosphere, a crater can last for hundreds of thousands of years if not millions. On Earth, small craters are buried or worn away relatively quickly. The second factor is ...

28

No spacecraft has been yet lost to the asteroid belt. In fact, we have the opposite example of missing an asteroid when it was even targeted, like was the case with MINERVA lander of the JAXA's Hayabusa deep space probe, missing the 25143 Itokawa asteroid. Why haven't we lost any spacecraft due to collision with asteroids in the asteroid belt is also pretty ...

27

Definitely not in current shape, as it depends on tightly packed soil/rock to provide an opposing force to resistance of the ground/rock against the drill. Asteroids, with low gravity, will be far less stable and this sort of forces could easily break apart smaller ones. Also, starting the tunnel would be a serious problem, as instead of 1g to keep the ...

27

Yes. (But it requires a bit of dishonesty.) Simply because an "extinction level" asteroid does sufficiently limit the possible nature of the object. To be extinction-level, it would need to be quite large. More than 3km in diameter. To be asteroid, it would need to be an inner-solar-system object. This pretty much limits it to being a large ...

26

Ulysses, the shuttle-launched joint NASA/ESA probe to study the sun's polar regions, ran through three comet tails, more or less by chance. Ulysses Catches Record for Catching Comets by Their Tails ...comet Hyakutake ...On May 1, 1996, while Ulysses was cruising through space studying the solar wind, its data suddenly went wild for a few hours. The once-...

25

This report shows that Mars is hit over 200 times a year by meteorites big and/or fast enough to leave a crater of typically 12.8 feet diameter. Earth strikes of this size are thankfully much rarer, so yes: Mars is more at risk. Possible reasons for this are: a) Mars is "only" 100 million km from the asteroid belt, whereas Earth is 180 million km away; b)...

24

Finding macroscopic (i.e., big enough to actually use) pure-iron meteoroids appears to be extremely low-probability. Certainly the bulk composition of the metals in Earth (good references here, here, and here) and metallic meteorites is iron plus nickel, a siderophile, and a few also-rans, like sulfur and oxygen, and other siderophile metals like cobalt. ...

22

The Voyager probes are outside the Kuiper belt now, and have a very long way to go before entering the Oort cloud. They are now in a place that is almost completely devoid of matter. Or at least I couldn't find any estimates as to how dense the solar system is there. But what about when they where still in the Kuiper belt? If Wikipedia is to be believed, ...

20

It does not have any known objects. It seems unlikely that it would happen, although it could theoretically happen for a short period of time. There are few stable orbits around the Moon, and even fewer that are likely to remain stable for any length of time. Even Lunar orbiting missions don't remain stable, and they have a better chance than a random object ...

19

With all the hype in the news this was surprisingly hard to research for specifically 2011 UW158. I never did find a source for the claim on the value, though the Slooh Community Observatory put the claim at "\$300 billion to as much as \$5.4 trillion dollars worth of precious metals and minerals". The answer basically seems to come down to: we've analyzed ...

18

The asteroid belt isn't nearly as dense as popular media makes it out to be. An answer from the Dawn Mission's FAQ, specifically "What is the average distance between individual asteroids? (6/13/10)", helps here. Asteroids are not distributed uniformly in the asteroid belt, but could be approximated to be evenly spaced in a region from 2.2 AU (1 AU ...

17

Spaceships will keep travelling in their orbits just the same as comets or asteroids, without fuel. The exception is that spacecraft in low orbit are affected by the upper fringe of the atmosphere, and need a slight boost every few months. Spaceships need fuel to change their course or to fly from the ground into space and back. Typically they only run their ...

16

Our Moon makes this possible. An asteroid with a low $V_\infty$ with respect to Earth making a close flyby of the Moon in the right direction could get into a distant orbit around the Earth. That object would likely continue to encounter the Moon, and could be ejected again. It is important to realize that things cannot just drift into orbit without ...

15

The asteroid belt is roughly 6 Astronomical Units wide, and so when it is drawn only 600 pixels wide with each asteroid a handful of pixels wide, you end up with each asteroid being five times bigger than the Sun! I've borrowed a small piece of the image used in @jos' excellent answer to show what I mean. As pointed out in this answer, Wikipedia says: ...

15

Rosetta collected dust from 67P/Churyumov-Gerasimenko and analyzed it under an atomic force microscope, without landing on the cometary body itself; depending on your definitions this would seem to imply having flown through its tail. Navigation isn't much of an issue; you simply navigate close to the cometary body and hang out on the sunny side -- though I ...

14

It would take vastly more $\Delta V$ to get it to a low-Earth orbit. The targets selected are close enough to Earth's orbit about the Sun that it only takes around $200\,\mathrm{m/s}$ to get it into a distant retrograde orbit about the Moon. To get the thing to a low Earth orbit would be around $3\,\mathrm{km/s}$. The tyranny of the rocket equation makes ...

14

The principles of Difference Image Analysis (DIA) or Difference Imaging, which is very common in modern astronomy for finding new transient sources (e.g. asteroids, variable stars, including microlensing events, and supernovae), is simple in principle but complicated by a lot of practical details caused by real-world observations. The basis, which is set ...

13

Yes. Planetary Differentiation is the key here. When enough smaller asteroids smash together and form a big enough body, the heavy stuff sinks to the bottom (iron and other metals), middle layers tend to be formed of silicates (i.e. sand and rocks), and the lighter stuff floats on top (water, methane). (Mind you, the examples here are based on the ...

13

At this point in time it seems doubtful that we could intercept and deflect an asteroid large enough to justify being deflected. This is simply a matter of momentum, a large asteroid has a great deal of momentum and the puny little spaceships we can presently intercept an asteroid with can impart only very little momentum. The only way we can substantially ...

13

The challenge here is getting the pusher plate into position. The potential impactor is not generally traveling on an orbit that can be reached with low DV. So the only way with current(ish) technology to get 100-1000 tons of pusher plate alongside and stationary to an asteroid is if it uses an Orion drive. And if you have a fully working Orion then you can ...

13

note: This is a historical answer, and explains how to find tiny asteroids close by. The OP has clarified they want a profitably mineable-sized asteroid so there is room for more answers. Previous wording: ...specific asteroids and/or their asteroid orbit type... As discussed in Have there been any documented mini-moons since 2006 RH120?, "mini-moons&...

13

Yes, radar is one of the useful tools for detecting and observing asteroids. It is however most effective at closer ranges, like near-earth asteroid, since sending out a radio wave and bouncing it back scales with the inverse fourth power of distance. The most capable telescope for radar observation of asteroids was the Arecibo telescope, until it collapsed ...

12

Both questions are really hard to answer. You can only estimate how often this happens. There is no monitoring system, which constantly observes the entire sky. There is an unknown number of asteroids and comets in the solar system. Right now, the rate of newly discovered objects increases exponentially (due to better and better technology). Today's number ...

12

Let's break your question into separate tasks: Autonomous orbit determination (autonomous because the DSN won't be there to help you when you need it) Autonomous attitude determination Situational awareness for formation flying (relative positions, velocities, attitudes and attitude rates), most efficiently done in a cooperative manner Cooperative collision ...

12

It depends on the size of the asteroid. According to this article, if the asteroid's diameter is more than 8 km, you can walk on it without the fist step sending you flying off. When the asteroid is smaller, the article proposes to loop a cable loosely around the asteroid. Astronauts can tether themselves to this cable and walk around. Of course this limits ...

12

Unlike chemical rockets such as hydrazine (a monopropellant, which doesn't require separate oxidizer and fuel to burn), water is just the reaction mass — not the energy source. The Comet-1 thruster that the DSi Prospector series is using is electrothermal, so it requires a substantial electrical power supply in order to energize the water (presumably ...

12

I would guess no. What makes the extinction level events so dangerous for us isn't the impact or the shockwave. A shockwave on Mars won't do much damage since the atmosphere is very thin anyway, and it's likely that colonists are mostly living underground (using the ground as radiation shielding). What makes the big impact strikes so dangerous on Earth is ...

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