Author Topic: Falcon Heavy soars; SpaceX lands critical NASA double asteroid redirect launch  (Read 2711 times)

Online Chris Bergin

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Falcon Heavy soars; SpaceX lands critical NASA double asteroid redirect launch - by Chris Gebhardt

https://www.nasaspaceflight.com/2019/04/falcon-heavy-spacex-nasa-asteroid-redirect/

https://twitter.com/NASASpaceflight/status/1116766945972576256
« Last Edit: 04/12/2019 06:18 pm by Chris Bergin »

Offline Roy_H

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I really hope the Italian cubesat becomes part of the mission. The photos of the impact will be invaluable.
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Online meciel

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Doing some napkin math about that asteroid redirect, 0.5mm/s will only change its position by ~30 km in a 2 year orbit, but I might be missing something.

Online rakaydos

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Doing some napkin math about that asteroid redirect, 0.5mm/s will only change its position by ~30 km in a 2 year orbit, but I might be missing something.
Oberth. You're missing Oberth.

The .5mm/s doesnt affect much itself, but the changes it does have butterfly out of proportion. 30km closer to a planet flings it farther off course, where it interacts with things it wouldnt have interacted with, ect.

And of course if we didnt have multiplle orbits to save earth, we'd use more that a single spaceprobe to redirect the asteroid.

Offline Robotbeat

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More like "keyhole", not Oberth. Often, potentially hazardous asteroids make several trips near earth. On these passes, the gravity of Earth acts as a big lever, bending the path of the asteroid slightly so the next near-pass will actually hit. This only occurs for a narrow part of the possible positions of an asteroid, a position called a "keyhole." So even a slight push could push a potentially hazardous asteroid out of a keyhole. Keyhole paper: https://www.researchgate.net/publication/228813049_Deflecting_a_Hazardous_Near-Earth_Object_1_st_IAA_Planetary_Defense_Conference_Protecting_Earth_from_Asteroids_27-30_April_2009_Granada_Spain

Also, remember this interceptor is tiny. About 500kg. If there was a real need, we could construct one ten or maybe even 100 times bigger (something like Starship could allow one nearly 1000 times as big, expendable). That'd allow a much more powerful punch. And several interceptors could be constructed and used. A dozen 50 ton interceptors could push such an object multiple Earth radii away within 2 years.

Additionally, the napkin sketch may not take into account the possible multiplying effect of debris from the impact.
« Last Edit: 04/15/2019 04:47 am by Robotbeat »
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Online meekGee

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More like "keyhole", not Oberth. Often, potentially hazardous asteroids make several trips near earth. On these passes, the gravity of Earth acts as a big lever, bending the path of the asteroid slightly so the next near-pass will actually hit. This only occurs for a narrow part of the possible positions of an asteroid, a position called a "keyhole." So even a slight push could push a potentially hazardous asteroid out of a keyhole. Keyhole paper: https://www.researchgate.net/publication/228813049_Deflecting_a_Hazardous_Near-Earth_Object_1_st_IAA_Planetary_Defense_Conference_Protecting_Earth_from_Asteroids_27-30_April_2009_Granada_Spain

Also, remember this interceptor is tiny. About 500kg. If there was a real need, we could construct one ten or maybe even 100 times bigger (something like Starship could allow one nearly 1000 times as big, expendable). That'd allow a much more powerful punch. And several interceptors could be constructed and used. A dozen 50 ton interceptors could push such an object multiple Earth radii away within 2 years.

Additionally, the napkin sketch may not take into account the possible multiplying effect of debris from the impact.

OT, but the best plan I've hear so far is to pre-position large rocks in very high orbit - much larger masses than an interceptor, can be but much smaller than the thread asteroid.  Upon detection, move the rocks as interceptors into the path of the threat.
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Online Zed_Noir

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More like "keyhole", not Oberth. Often, potentially hazardous asteroids make several trips near earth. On these passes, the gravity of Earth acts as a big lever, bending the path of the asteroid slightly so the next near-pass will actually hit. This only occurs for a narrow part of the possible positions of an asteroid, a position called a "keyhole." So even a slight push could push a potentially hazardous asteroid out of a keyhole. Keyhole paper: https://www.researchgate.net/publication/228813049_Deflecting_a_Hazardous_Near-Earth_Object_1_st_IAA_Planetary_Defense_Conference_Protecting_Earth_from_Asteroids_27-30_April_2009_Granada_Spain

Also, remember this interceptor is tiny. About 500kg. If there was a real need, we could construct one ten or maybe even 100 times bigger (something like Starship could allow one nearly 1000 times as big, expendable). That'd allow a much more powerful punch. And several interceptors could be constructed and used. A dozen 50 ton interceptors could push such an object multiple Earth radii away within 2 years.

Additionally, the napkin sketch may not take into account the possible multiplying effect of debris from the impact.

OT, but the best plan I've hear so far is to pre-position large rocks in very high orbit - much larger masses than an interceptor, can be but much smaller than the thread asteroid.  Upon detection, move the rocks as interceptors into the path of the threat.

Of course how to get the rocks to the pre-position orbit in the first place? Also how to keep the rocks there? Never mind that moving those rock to intercept will required some sort of Space Tugs.

[ wacky idea ]
It is much simpler to do kinetic strike with a kamikaze Starship Tanker with extra propellant tankage that is top up. High speed impact with a mass of about 1300+ tonnes should redirect the flight path of the incoming asteroid. Especially if the intercept happens in the "Keyhole" part of the incoming asteroid's flightpath.

Plus the bonus closeup observations of the asteroid with the Tanker's augmented sensor suite during the terminal targeting guidance phase.
[ /wacky idea ]




Online meekGee

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More like "keyhole", not Oberth. Often, potentially hazardous asteroids make several trips near earth. On these passes, the gravity of Earth acts as a big lever, bending the path of the asteroid slightly so the next near-pass will actually hit. This only occurs for a narrow part of the possible positions of an asteroid, a position called a "keyhole." So even a slight push could push a potentially hazardous asteroid out of a keyhole. Keyhole paper: https://www.researchgate.net/publication/228813049_Deflecting_a_Hazardous_Near-Earth_Object_1_st_IAA_Planetary_Defense_Conference_Protecting_Earth_from_Asteroids_27-30_April_2009_Granada_Spain

Also, remember this interceptor is tiny. About 500kg. If there was a real need, we could construct one ten or maybe even 100 times bigger (something like Starship could allow one nearly 1000 times as big, expendable). That'd allow a much more powerful punch. And several interceptors could be constructed and used. A dozen 50 ton interceptors could push such an object multiple Earth radii away within 2 years.

Additionally, the napkin sketch may not take into account the possible multiplying effect of debris from the impact.

OT, but the best plan I've hear so far is to pre-position large rocks in very high orbit - much larger masses than an interceptor, can be but much smaller than the thread asteroid.  Upon detection, move the rocks as interceptors into the path of the threat.

Of course how to get the rocks to the pre-position orbit in the first place? Also how to keep the rocks there? Never mind that moving those rock to intercept will required some sort of Space Tugs.


Of course, but the idea is that the interceptors are an 2 OOMs easier to deflect, and they don't need much dV since most of it is provided by the incoming object.   However, they are 2 OOMs heavier than your space probe.
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Offline IainMcClatchie

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OT, but the best plan I've hear so far is to pre-position large rocks in very high orbit - much larger masses than an interceptor, can be but much smaller than the thread asteroid.  Upon detection, move the rocks as interceptors into the path of the threat.

Instead of one impact, you get multiple impacts.  A 20 meter diameter rocky asteroid arriving at 40 km/s is about 2 megatons.  Any explosion that size or larger will radiate most of its energy out into space, so that the combined effect of 10 impacts each 1 megaton is much worse than a 10 megaton explosion.  Breaking up a gigaton impactor (150 meters diameter) is a horrible idea, even if only 10% of the incoming mass hits the Earth.

Each rock is in some orbital plane.  Multiple rocks might be in many different orbital planes, maybe you would have thousands of rocks in many dozens of orbital planes, something like the SpaceX StarLink constellation.  This constellation would have be to at a fairly high orbit, probably beyond the Moon, so as to give most of the deflected threat asteroid debris some time to separate from the track that previously led to Earth impact.  If you had 30 orbital planes at about the Moon distance, you'd have a maximum of 3 Earth diameter separation between the planes, and if you had 1000 rocks spread around all these planes, you'd have almost 6 Earth diameter separation between the rocks.

To achieve intercept, you'll probably have to deviate the rock by as much as 4 or 5 Earth diameters.  I suppose this would be easier than deviating the threat asteroid by 1 Earth diameter in a smaller amount of time, as it takes time to get a booster onto the threat asteroid.  But it does mean moving thousands of rocks through many km/s of delta-V to get them into position.  The potential for interactions between the shield rocks and the moon or sun leading to shield rocks crashing into one another seems large.

Offline jerwah

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[ wacky idea ]
It is much simpler to do kinetic strike with a kamikaze Starship Tanker with extra propellant tankage that is top up. High speed impact with a mass of about 1300+ tonnes should redirect the flight path of the incoming asteroid. Especially if the intercept happens in the "Keyhole" part of the incoming asteroid's flightpath.

Plus the bonus closeup observations of the asteroid with the Tanker's augmented sensor suite during the terminal targeting guidance phase.
[ /wacky idea ]

A starship tanker would probably be far more effective as a gravity tractor than as a bomb. Still get all of the close observation benefits and none of the explodey stuff.

Online Zed_Noir

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[ wacky idea ]
It is much simpler to do kinetic strike with a kamikaze Starship Tanker with extra propellant tankage that is top up. High speed impact with a mass of about 1300+ tonnes should redirect the flight path of the incoming asteroid. Especially if the intercept happens in the "Keyhole" part of the incoming asteroid's flightpath.

Plus the bonus closeup observations of the asteroid with the Tanker's augmented sensor suite during the terminal targeting guidance phase.
[ /wacky idea ]

A starship tanker would probably be far more effective as a gravity tractor than as a bomb. Still get all of the close observation benefits and none of the explodey stuff.

The force of a Starship Tanker kinetic Impact and the force from a Starship Tanker Gravity Tractor is a few magnitude difference. Presuming you can rendezvous with the incoming asteroid to begin with due to time constrain and/or physics.

Likely in the near future there will not be much warning time to attempt a gravity tractor diversion mission. Due to the sparse resources for finding Earth orbit crossing objects.


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