Can Jet Engines Save Earth from a Collision with an Asteroid?

[Tee1977]

Hello people,

I got a question and please do not understand it as a fake question.

In theory would it be possible that when it would come to a collision between the Earth and a big sized asteroid, huge jet engines placed on different places on Earth could bring Earth out of orbit and then after the asteroid has passed the Earth without any problems bringing Earth then back to correct orbit again ?

Thanx !

Kay

 

[Borg]

Hello people,

I got a question and please do not understand it as a fake question.

In theory would it be possible that when it would come to a collision between the Earth and a big sized asteroid, huge jet engines placed on different places on Earth could bring Earth out of orbit and then after the asteroid has passed the Earth without any problems bringing Earth then back to correct orbit again ?

Thanx !

Kay

No, that wouldn't work or even make any sense. It would be far easier to move the asteroid or blow it up.

 

[Noisy Rhysling]

Mass of the Earth exceeds any conceivable system to move it. Near Earth Objects (NEOs) would be far easier to move. Check Google for various strategies for this.

 

[Janus]

Hello people,

I got a question and please do not understand it as a fake question.

In theory would it be possible that when it would come to a collision between the Earth and a big sized asteroid, huge jet engines placed on different places on Earth could bring Earth out of orbit and then after the asteroid has passed the Earth without any problems bringing Earth then back to correct orbit again ?

Thanx !

Kay

Take a typical turbo-jet, a General electric CJ805-23B. Even if you covered every square inch of one side of the Earth with them, all their total thrust together would only be enough to move the Earth some 165 km after running them continuously for one week.
But it is worse than that. They wouldn't actually produce any net movement of the Earth at all. The jet engine throws its exhaust upwards away form the Earth, and you initially get a reaction from the Earth moving the other way. But as the exhaust climbs away from the surface, Earth's gravity pulls back on it slowing its climb. This same gravitational pull slows the Earth's movement in the opposite direction. By the time the exhaust has reached its peak height and begins to fall back to Earth, the Earth has stopped its motion and starts to return to its starting point. They both end up meeting again where they started.
The only way to produce a net thrust that moves the Earth is for the initial exhaust velocity to be fast enough that the exhaust never falls back to Earth. This equals the escape velocity from Earth or ~11 km/sec. Our best chemical rockets can't produce exhaust velocities of even half of that. So no number of jet or rocket engines mounted on the Earth could move it even an inch.

 

[Rubidium_71]

Current Earth government policy would be to ignore the possibility (and eventual probability) of such an impact, argue until it's too late to do anything about it and then go "duh" after the asteroid strikes Earth (assuming there's anyone left to say "duh" at that point.) Never underestimate human arrogance (an asteroid wouldn't dare hit our planet!), superstition (gawd will save us if we just believe in magic), laziness (let the next generation worry about that sort of thing) and (especially) the George Costanza-level cheapness inherent in most governments. Better to spend trillions on massive arsenals of weapons and save cash by cutting space exploration down to nothing. Who cares about space anyway?

 

[jackwhirl]

This episode of PBS Space Time discusses various options.

 

[Noisy Rhysling]

Current Earth government policy would be to ignore the possibility (and eventual probability) of such an impact, argue until it's too late to do anything about it and then go "duh" after the asteroid strikes Earth (assuming there's anyone left to say "duh" at that point.) Never underestimate human arrogance (an asteroid wouldn't dare hit our planet!), superstition (gawd will save us if we just believe in magic), laziness (let the next generation worry about that sort of thing) and (especially) the George Costanza-level cheapness inherent in most governments. Better to spend trillions on massive arsenals of weapons and save cash by cutting space exploration down to nothing. Who cares about space anyway?

I'm curious as to which governments have this policy.

 

[newjerseyrunner]

Current Earth government policy would be to ignore the possibility (and eventual probability) of such an impact, argue until it's too late to do anything about it and then go "duh" after the asteroid strikes Earth (assuming there's anyone left to say "duh" at that point.) Never underestimate human arrogance (an asteroid wouldn't dare hit our planet!), superstition (gawd will save us if we just believe in magic), laziness (let the next generation worry about that sort of thing) and (especially) the George Costanza-level cheapness inherent in most governments. Better to spend trillions on massive arsenals of weapons and save cash by cutting space exploration down to nothing. Who cares about space anyway?

I'm curious as to which governments have this policy.

Me too. The US government just funded a complete survey of the sky to find NEOs. After the explosion in Russia, they started creating plans to use their missiles to defend against large asteroids. Considering that there are very few countries that could actually do anything anyway, I imagine that the policy of most nations is "let the Americans and Russians deal with it."

 

[Rubidium_71]

I'm curious as to which governments have this policy.

No real official policy that I'm aware of, I suppose, just the general tendencies of humanity we see every day. As far as inability or unwillingness to address a problem like that, I think most governments fall into that category. We still have people that deny global climate change, the Apollo moon landings and evolution. I don't think it's a stretch to imagine human arrogance and ignorance putting a damper on a response to an impending collision until it's too late.
But that's just my pessimistic opinion.

I imagine that the policy of most nations is "let the Americans and Russians deal with it."

I agree with you. Venezuela is not going to save the world any time soon. Hopefully something as important as that could get through Congress in time... hopefully. I too heard that they were "starting plans." Let me know when they're actually finished and are ready to go. Hopefully those plans don't come under budget cuts ("no asteroid out there today, so let's save some money!") They've been whittling down space exploration even more lately.
That said, necessity is the mother of invention, so an impending impact would be likely to spur quick action. Trouble is, even with their sky survey, there's a lot of elusive objects out there. A lot of the time the first clue to their approach is when they burn through the atmosphere. In that case, the aforementioned "duh" conclusion would be more likely. While I respect your points, I think the two of you have more faith in humanity than I do.

 

[Tee1977]

Thanx for info. I like the option of Graffiti! :)
Ok let us think about of an even worse problem that now a planet sized object is on collision course to earth.
Is there any chance to prevent the impact of another planet sized object with the options mentioned in the video ?
Thanx again!

 

[Rubidium_71]

Doubtful that a planetary body could be diverted, but that depends on a lot of factors. What's the offending planet composed of? In any event, the best option in that scenario would be to flee Earth altogether and take up residence elsewhere. I think that's more credible than trying to avert a planetary collision.

 

[Noisy Rhysling]

How many people could we get to Mars right now, and how long could they live there without support from Earth?

 

[newjerseyrunner]

Hopefully something as important as that could get through Congress in time... hopefully.

I'm not sure an emergency of this scale would require the Congress. It'd be a matter of national security. I would think the president would declare a state of emergency and use the military for whatever is necessary. He needs congress to declare war, not handle natural emergencies. Even if for some reason there were legal hurdles for Obama, I doubt Putin would have the same hurdles, or would care.

 

[newjerseyrunner]

How many people could we get to Mars right now, and how long could they live there without support from Earth?

None. Humans neither have the rockets or the ships for such a mission. We don't have the capability to go to the moon right now, our current rockets just aren't powerful enough.

 

[Noisy Rhysling]

I'm not sure an emergency of this scale would require the Congress. It'd be a matter of national security. I would think the president would declare a state of emergency and use the military for whatever is necessary. He needs congress to declare war, not handle natural emergencies. Even if for some reason there were legal hurdles for Obama, I doubt Putin would have the same hurdles, or would care.

Congress would, of course, be jostling his elbow. Was ever thus.

 

[Rubidium_71]

He needs congress to declare war, not handle natural emergencies. Even if for some reason there were legal hurdles for Obama, I doubt Putin would have the same hurdles, or would care.

True. Hopefully bureaucracy could be cut out in a situation that grim. If it was detected in time by a fully funded sufficiently advanced program.

We don't have the capability to go to the moon right now, our current rockets just aren't powerful enough.

Therein lies the rub, my friend. Victory loves preparation. The current rockets won't do against an impending impactor, so something new would need to be constructed. You'd need some pretty serious lead time to successfully rush something like that into production. Hurrying in the case of space travel has not always served America or Russia very well in the past. The Apollo 1 astronauts were, in a sense, victims of a program that was going too fast and cutting corners. The Soviet Nedelin Catastrophe is a great example of how short cuts create danger in such situations. Even poor Matt Damon was screwed over by his supply rocket blowing up (although the stated reason for said fictional rocket exploding was dubious). ;)
I hope that detection and prevention are getting the attention they deserve. I hope that events like what happened in Moscow have gotten the serious attention of politicians. However, I still have very little faith in politicians and even less confidence in practical government spending. Hopefully we'll never have to find out in real life.

 

[newjerseyrunner]

Here's the thing though, in defense, you don't need to send people. We do have the rockets to send large objects into deep space, they just aren't safe enough for a human crew. With huge amounts of money, prototypes can also be completed very quickly. If the government gave Elon Musk a few billion dollars and told him to get the Falcon Heavy lift vehicle ready in a month, they'd probably be able to do it. It wouldn't be very safe, but it'd certainly be safe enough for a warhead. And in an emergency situation, if for some reason a human needed to go, the military is not above putting pilots at risk to get the job done. The odds of intercepting an asteroid in an prototype would probably be about the same as fighting the Nazi Luftwaffe for nine months.

 

[Rubidium_71]

We do have the rockets to send large objects into deep space

Then why do NASA probes always have to use gravity assists to fling our probes to the outer solar system? Not trying to be difficult there, just actually curious.

With huge amounts of money, prototypes can also be completed very quickly. If the government gave Elon Musk a few billion dollars and told him to get the Falcon Heavy lift vehicle ready in a month

For that to even come close to fruition, you must first have that month. Objects like the one over Moscow were not detected while in "deep space"; people didn't know about them until they were already in the atmosphere. Most of the events of this type to date have not been detected in advance. Too late for Mr. Musk to save the day in those scenarios. Detection must be thorough and constantly funded. Budget cuts continue to plague space endeavors to this day, which makes me skeptical. Governments prefer to spend their money on weapons that kill other people, not theoretical space rocks. Planning ahead isn't necessarily a strong suit for humanity.
I still stick to my original outlook - in the space rock vs Earth government contest (at least at present) the space rock is going to hit the Earth most of the time. I guess it boils down to the old James Branch Cabell quote with me - "The optimist proclaims that we live in the best of all possible worlds; and the pessimist fears this is true." While Cabell chose neither, I am in the pessimist group.

 

[newjerseyrunner]

There is an extremely good chance that we'll see the object coming with way more than a month's warning. The object that hit Russia was a few meters across. It was dangerous, but not a threat to the country. Larger objects would be detected by IR surveys that are constantly sweeping the sky. Detection is cheap and is constantly being funded. All it takes is a big IR telescope and some computer software.

Gravity assist simply makes it easier and way faster. Our rockets are capable of throwing objects out pretty far. If we had to, we could probably send a probe to Mars in a straight shot, it's just faster to fling it around the Earth a few times.

 

[Noisy Rhysling]

I learned back in 1970 that it's the one you don't see that gets you.

 

[Janus]

There is an extremely good chance that we'll see the object coming with way more than a month's warning. The object that hit Russia was a few meters across. It was dangerous, but not a threat to the country. Larger objects would be detected by IR surveys that are constantly sweeping the sky. Detection is cheap and is constantly being funded. All it takes is a big IR telescope and some computer software.

Gravity assist simply makes it easier and way faster. Our rockets are capable of throwing objects out pretty far. If we had to, we could probably send a probe to Mars in a straight shot, it's just faster to fling it around the Earth a few times.

As examples:
The New Horizons probe left Earth with enough velocity to reach Pluto on its own, the Jupiter gravity assist was to shave time off of the trip.
The Mars Science Laboratory, which included the Curiosity rover, was launched on a direct trajectory to Mars.
The Galileo probe used gravity assists by Venus and Earth to reach Jupiter, but that was only because the originally planned booster stage that would have put it on a direct trajectory couldn't be carried by the shuttle due to new safety rules put in place after the Challenger disaster.

Also, I'm pretty sure that no mission to Mars has used a gravity assist, and if it were to, it wouldn't be to save time. Waiting for the probe to return to the Earth after launch would add time to the trip.

 

[newjerseyrunner]

The Mars Science Laboratory, which included the Curiosity rover, was launched on a direct trajectory to Mars.

Didn't it to 6 loops around the Earth first?

https://qph.is.quoracdn.net/main-qimg-921506a78b2bb8422ef9d7aa200d0b98?convert_to_webp=true

 

[Janus]

Didn't it to 6 loops around the Earth first?

https://qph.is.quoracdn.net/main-qimg-921506a78b2bb8422ef9d7aa200d0b98?convert_to_webp=true

But those weren't gravity assists in the sense of the gravity slingshot which borrows orbital velocity from the planet with no use of thrust. All those orbit raising operations were done by firing the probe's engines at perigee. It was done this way to take advantage of the fact that changes in orbital velocity are more effective when made at periapis (Oberth effect). Rather than doing one long burn, where the craft would have been some distance from perigee for much of the burn, many short burns at different perigee passes were done.

 

[Rubidium_71]

Detection is cheap and is constantly being funded.

I am curious - which current program do you think has the best chance of saving Earth from a highly damaging impact? Let's say, something large enough to lay waste to a major city and sizes above that.

There is an extremely good chance that we'll see the object coming with way more than a month's warning.

Define good. So far we've detected and intercepted zero threatening objects in recorded human history. Of course, it's a good thing the opportunity doesn't come up too often. Once we've got even one successful early detection/intervention under our belt, I might feel more confident in our planet's abilities.

An interesting article from a few years ago...some excerpts I think have a little relevance here:

A newfound asteroid gave Earth a close shave early today, zipping between our planet and the moon just two days after astronomers first spotted it.

The near-Earth asteroid 2012 XE54, which was discovered Sunday (Dec. 9), came within 140,000 miles (230,000 kilometers) of our planet at about 5 a.m. EST (1000 GMT) Tuesday (Dec. 11), researchers said. For comparison, the moon orbits Earth at an average distance of 240,000 miles or so (386,000 km).

Astronomers estimate that 2012 XE54 is about 120 feet (36 meters) wide — big enough to cause substantial damage if it slams into Earth someday. An object of similar size flattened 800 square miles (2,000 square km) of forest when it exploded above Siberia's Podkamennaya Tunguska River in 1908.

Now, the Tunguska object certainly wasn't an extinction-sized body, but in my opinion it was a potential city-killer. I think we can all agree Mr. Musk will need more than two days to save a city from such devastation - or the world. I would also suggest that protecting cities is something an early detection and prevention system is going to have to consider in addition to looking for extinction type impactors.

Scientists have discovered about 9,000 near-Earth asteroids to date, but perhaps a million or more such space rocks are thought to exist. So far, researchers have spotted less than 30 percent of these large space rocks, which could obliterate an area the size of a state if they slammed into Earth.

I'm sure there have been amazing innovations since this was written in 2012, but claiming that we've got a complete handle on this problem today is dubious in my opinion. We would've had to catalogue most of the extra 70% of these objects in just 4 years. Also, the million or so additional objects they refer to are not necessarily on fixed courses, they interact with other forces and bodies as they travel. They can be very unpredictable when it comes to their possible future behavior.

Earth is speeding down a highway at night at 67,000 mph without brakes or steering and it's path is littered with ever-changing random unmarked intersections. I think there is still a gap in early detection and rapid prevention that needs to be covered. I still don't have a lot of confidence in governments. Humanity better get crackin' if it intends to boast total knowledge and power over these objects in the future.

For the full article...
http://www.space.com/18854-newfound-asteroid-close-flyby-earth.html

 

[newjerseyrunner]

NEO or ATLAS., they're the most thorough asteroid surveys.

Where did you get the data that scientists think they've only found 30% of NEOs? We've found 95% of civilization destroyers, and are on track to find 90% of city killers by 2020. Based on the rate at which we find them, and assuming a bell curve, we can figure out what ratio we've found even if we don't know how many there are.

 

[Rubidium_71]

NEO or ATLAS., they're the most thorough asteroid surveys.

I'm thinking you're referencing The Asteroid Terrestrial-impact Last Alert System when you site ATLAS. From what I've read they were still in proof of concept as recently as last year. They do have a grant, but that only takes them through the design phase and into the first couple of years of operation. It sounded like after 2 years they would need to find additional funds beyond this one grant. They're also operating under some limitations, projecting only a one week warning for objects 150 feet in diameter and a three week warning for a 390 foot object. This is provided that the object in question is not too close to the Sun to be detected.

I see NEO is where you get the 90% statistic from. Of course, if one believes that 90% estimate to be accurate, that leaves a bunch of random objects out there in that dark 10%. All it takes is one. Good thing NEO is part of NASA, they've never had their budget cut. ;)

Where did you get the data that scientists think they've only found 30% of NEOs?

From the 2012 article I quoted. The link was at the bottom of the post, but here it is again:
http://www.space.com/18854-newfound-asteroid-close-flyby-earth.html
Beyond that, you'd have to ask Space.com where they got their numbers from.

assuming a bell curve, we can figure out what ratio we've found even if we don't know how many there are.

We certainly can try to estimate a ratio. Rough calculations like that can possibly be misleading, though. After all, we have things like the Fermi paradox contradicting the Drake equation, showing how fuzzy speculation and probability math can be. Even our own Solar System is awfully big to be making assumptions.
That said, it's still good to see early detection programs like ATLAS and NEO in motion but from what I can tell we're a far cry from swatting these objects away at a comfortable distance from Earth. The notion of a last minute desperate effort isn't really appealing either. I don't see any reason to change my original position. I think that there needs to be better detection/early interception capability before folks can dismiss the idea of a catastrophic impact to avoid the "duh" scenario I speculated about early on.

 

[newjerseyrunner]

The rate at which we discover asteroids is not at all like the Fermi Paradox. There are literally variables in the Drake equation that we don't know, we also have no way of knowing how a more advanced civilization would look and how to see it. Asteroids are just rocks, they glow in IR and if we're seeing new ones at an ever decreasing rate, it's indicative of the fact that we found most of them. We'll asymptotically approach zero and how close we get tells us what percentage are left. While we need more power to find them all, the likelihood is dropping. You'll never get a likelihood of zero, the goal is just to get as close to it as possible. I'd rather have 10% of asteroids unaccounted for than 50%.

Either way, both the US and Russia do have the capability to shoot a nuclear weapon at an asteroid. The bomb would be detonated near the surface, which would cause the surface to vaporize and eject away, acting as thrust and changing it's trajectory. Reliability is another matter.

 

[Daymare]

Then why do NASA probes always have to use gravity assists to fling our probes to the outer solar system? Not trying to be difficult there, just actually curious.

The main reason is its much easier to accelerate spacecraft by gravity thrust than by burning up fuel.Moreover just imagine the amount of fuel it would take if the voyager was propelled by fuel!Not very cost effective or practical either.

 

[EnumaElish]

A planet-sized body can be destroyed by any of the methods described here: https://qntm.org/destroy
Not all are achivable with present technology, and others may require more time than we may actually have between detection and collision.

Changing Earth's orbit could itself cause great harm, perhaps exceeding that from the impact if we just let it happen. As long as it's smaller than the moon.*

But - here goes: https://qntm.org/moving

See also http://boards.straightdope.com/sdmb/showthread.php?t=238847

IMO humanity's best course would be two-pronged: (1) get as many people on space station(s) and hope they survive the blast, and (2) hunker down like never before and keep fingers crossed that not all will perish.
————————————
*quoting from the first link:

Falling at the minimal impact velocity of 11 kilometres per second and assuming zero energy loss to heat and other energy forms, the cue ball would have to have roughly 60% of the mass of the Earth. Mars, the next planet out, "weighs" in at about 11% of Earth's mass

which implies that even a head-on impact with a Mars-sized object will doubtlessly devastate, but not necessarily pulverize the earth.

 

[Noisy Rhysling]

How many chunks flying off in what directions in those scenarios? Seem like if we blew a planet up we'd have more problems than with a single body.

 

[EnumaElish]

Humanity permitted to make simplifying assumptions.

 

[Noisy Rhysling]

Humanity permitted to make simplifying assumptions.

That kind of thing nearly got me killed a few times. I'm a fan of accuracy.

 

[Stephanus]

...For that to even come close to fruition, you must first have that month. Objects like the one over Moscow were not detected while in "deep space"; people didn't know about them until they were already in the atmosphere.

Yeah, I didn't know about the object either until it was already in the newspaper.

 

[newjerseyrunner]

How many chunks flying off in what directions in those scenarios? Seem like if we blew a planet up we'd have more problems than with a single body.

The nuclear deflection concept doesn't produce chunks, it produces vapor. The bomb itself doesn't actually push the asteroid much, but it vaporizes the surface on one side, which acts like a rocket.

 

[Rubidium_71]

The rate at which we discover asteroids is not at all like the Fermi Paradox.

The thing is, both the larger Universe and our own Solar System still have unknowns, despite our best efforts to analyze and quantify.

we're seeing new ones at an ever decreasing rate, it's indicative of the fact that we found most of them.

The NEO chart below seems to show a fairly steady rate of discovery, but it's not anywhere near zero yet. Lots of work to do yet, I think. I am skeptical of the 90% stat. Even when we've detected most of them the problem isn't solved. Just because it's detected doesn't mean it's on a leash. These objects can have their orbit influenced by a few different factors and it can be difficult for a project like ATLAS to detect an object if their radiant is not too close to the Sun.

Either way, both the US and Russia do have the capability to shoot a nuclear weapon at an asteroid.

I am not aware of a nuclear anti-impact facility being constructed or having been constructed. All of the nuclear weapons currently held are designed to strike targets on Earth (and some of those haven't been upgraded in decades). Since the nuclear weapon is often considered the magic bullet of object deflection, maybe they should set aside and maintain a specially designed group of them for striking the far more distant targets presented by asteroids.
Hurrying to assemble such a device at the last minute doesn't give me a whole lot of confidence. Time pressure and recklessness are not very compatible with nuclear innovation, just ask Harry Daghlian, Louis Slotin or the folks from the Chernobyl control room.
Progress in this area is being made, but it's got a ways to go.