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55 votes
Accepted

Why do many comets & asteroids keep moving through the solar system, but space ships need fuel to do so?

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 ...
Rory Alsop's user avatar
  • 13.6k
53 votes

Does NASA have an end-of-the-world policy?

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 ...
astrosnapper's user avatar
  • 2,506
34 votes
Accepted

Is Mars more at risk than Earth for asteroid collisions?

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 ...
Russell Borogove's user avatar
34 votes
Accepted

How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

The edge of Earth's Hill Sphere is about 929000 km, so in order to capture Apophis, it needs to decelerate from a hyperbolic orbit to an elliptical one with an apogee of at most 929000 km. In 2029, ...
WarpPrime's user avatar
  • 3,125
28 votes
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What processes create an object with an interstellar velocity?

The answer to 'how can it come blazing in with enough energy to exit again' is that if it started outside the solar system it would have been unusual for it to NOT leave again, since it would have ...
GremlinWranger's user avatar
27 votes

If an extinction-level asteroid were to be detected, could we avert it?

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 ...
CuteKItty_pleaseStopBArking's user avatar
26 votes

Could a Boring Company Excavation Tool be used to create a large circular chamber inside an asteroid?

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 ...
SF.'s user avatar
  • 55.1k
26 votes

How hard is it to fly through the tail of a comet? Has it been done?

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 ....
Organic Marble's user avatar
25 votes

Can we expect to find pure iron or only nickel-iron alloys in asteroids?

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, ...
Tom Spilker's user avatar
  • 18.3k
25 votes

Is Mars more at risk than Earth for asteroid collisions?

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, ...
Boodysaspie's user avatar
23 votes
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Is there any evidence from previous missions to asteroids that said asteroids have minable minerals?

There have been no sample return missions from M-type (metallic) asteroids. Their composition has been estimated from spectroscopic data and radar albedo. The IR spectra of these asteroids was matched ...
Woody's user avatar
  • 22.9k
18 votes
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Traveling through the asteriod belt?

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)",...
jos's user avatar
  • 1,093
18 votes

What caused the jitter in the DART video as it approached Dimorphos?

This is an extended comment to your self-answer, so I'm making it community. From your answer, As to why they weren't able to do a single, early course correction and just glide smoothly in for the ...
17 votes

Why do many comets & asteroids keep moving through the solar system, but space ships need fuel to do so?

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, ...
ikrase's user avatar
  • 8,923
16 votes
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Can an asteroid enter Earth orbit?

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 ...
Mark Adler's user avatar
  • 58.2k
15 votes

Traveling through the asteriod belt?

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 ...
uhoh's user avatar
  • 148k
15 votes

How hard is it to fly through the tail of a comet? Has it been done?

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 ...
Russell Borogove's user avatar
15 votes
Accepted

How to maintain balance and center of gravity when pushing a 100-ton piece of asteroid?

Two observations: Any reasonable way of nudging a NEO towards Earth requires doing a burn months or even years in advance. Compared to the burn time (here 1min), that means we have a lot of time to ...
SE - stop firing the good guys's user avatar
14 votes
Accepted

How can stellar images be "subtracted" from a sequence of exposures? (difference imaging)

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 ...
astrosnapper's user avatar
  • 2,506
14 votes

What asteroids have the least delta-v to reach?

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 ...
uhoh's user avatar
  • 148k
14 votes

Can we use something like RADAR to detect asteroids?

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 ...
SE - stop firing the good guys's user avatar
13 votes
Accepted

Could the Orion project pusher plate model be used for asteroid deflection?

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) ...
GremlinWranger's user avatar
13 votes

How could 99942 Apophis, in 2029, be captured and brought into a low Earth orbit?

In 2029? We can't. I doubt that that the next two closest approaches after 2029 (2036 and 2051) are within reach. We might be able to do it by 2116, or maybe even 2066. An object as large as Apophis ...
David Hammen's user avatar
  • 75.3k
13 votes

Is there an elegant method to stop an asteroid's spin?

I found at least 1 paper proposing enclosing the asteroid in a bag filled with gas. https://www.researchgate.net/publication/273913280_SHEPHERD_A_Concept_for_Gentle_Asteroid_Retrieval_with_a_Gas-...
lijat's user avatar
  • 1,778
13 votes

Is there an elegant method to stop an asteroid's spin?

Look at how satellites are commonly de-spinned, and apply it on a larger scale. A commonly done method is the Yo-yo de-spin where you have long ropes with weights, and extending them slowy from the ...
Ferrybig's user avatar
  • 231
13 votes

Is there any evidence from previous missions to asteroids that said asteroids have minable minerals?

Iron? Maybe, but... The first material being considered for mining (you may be surprised to find out) is water. The processes for mining water are generally well known and benign (ice has a very low ...
Wyck's user avatar
  • 1,593
13 votes
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Gravity assist (flyby/slingshot) from an asteroid?

Asteroids are too small to give a meaningful boost from a flyby. During an encounter, the relative entry and exit speed is equal $$ v_{in} = v_{out}$$ The only thing a mass does it bend the direction ...
SE - stop firing the good guys's user avatar
12 votes
Accepted

Would the one million people on Mars be killed by an impact equivalent to an Extinction Level Event on Earth

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 ...
Innovine's user avatar
  • 4,635
12 votes

Why is the Deep Space Industries Prospector 1 using water propellant instead of hydrazine?

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 ...
Nathan Tuggy's user avatar
  • 4,567
12 votes

How hard is it to fly through the tail of a comet? Has it been done?

The two Vega probes comes to mind, ending their implausible sounding mission of slipping balloons into the atmosphere of Venus with a flyby of Halley's comet in 1986. They took a heavy beating flying ...
SE - stop firing the good guys's user avatar

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