2007 Planetary Defense Conference

GW Johnson · 2018-10-24 09:37:48

Probably the best is basing the interceptor rockets in Earth orbit, but without warheads. They should be designed to carry either the revised nukes, or the slug impactors, pre-loaded onto appropriate carrier spacecraft.

These could be payloads stored not on board the interceptor rockets. You get the warning, select which response, and go load one up and shoot it (which requires men nearby doing an EV, not time to launch a crew).

It would be more of a docking adapter than the usual payload adapter assembly. Parking this stuff adjacent to ISS gives you a ready fast-response crew, and a reason to continue having an ISS. Parking the missiles without warheads loaded gets by the weapons-in-space fear.

We're still talking about really big 4 stage solids: departure residual speed relative to Earth needs to be in the 15-17 km/s range, I believe. They need to be designed for long service life like ICBM stages (~20 years+), and must be stored inside an illuminated tent-like shelter, so as not to have a hot side and a cold side from exposure to sunlight in space. You don't want hot and cold regions of propellant, that affects burn rates and ballistics drastically.

GW

Last edited by GW Johnson (2018-10-24 09:43:38)

elderflower · 2018-10-25 04:59:31

If you don't need a nuke, you could just use the final stage as an impactor. If liquid fuelled the rocket can be switched off at the appropriate time. The unspent propellant will carry just as much impact energy and momentum as would a slug warhead. Also, as the tanks rupture, there might be a soft chemical explosion or blevy as hypergolic components react.

GW Johnson · 2018-10-25 09:28:02

I was thinking of a carrier spacecraft with storable liquid propellants capable of carrying multiple individual payloads and making fine trajectory changes autonomously. The individual payloads could be slug impactors or nukes. To effectively change the trajectory of millions of tons of asteroid, especially late in the encounter, takes multiple hits. True whether impactor or nuke.

Impactors are moderately-small "pushes" individually. Less risk of disrupting the asteroid instead of altering its trajectory. But it takes a lot of small hits to do that, and not all at once. Nukes are "big push" items. It takes fewer of them, but the risk of disruption is far, far higher, except for the very rare solid metal asteroid.

The stony ones do not seem to be single rocks, and the carbonaceous ones are certainly not monolithic items. Your "push" force has to be less than whatever (still unknown) cohesive binding force holds the rubble piles together, or else you disrupt it into a shotgun blast.

That's why I thought the two carrier spacecraft would be different: one releases dozens to a hundred or so small impactors, one after the other, carefully aimed and timed. The other releases a single handful of nuclear bombs, also carefully aimed and timed. The impactors have to hit dead center. The nukes are also aimed dead center, but must burst just above the surface in order to work right: maybe dozens to a hundred-or-so meters. Hard to achieve accuracy like that traveling at several-to-dozens of km/sec relative to the asteroid.

We don't have that kind of guidance or those kinds of carrier spacecraft, nor do we have nuke fuzes that accurate. And nobody is yet working on such things. We're not even doing that good a job putting in place detection. Proof: Chelyabinsk was a surprise, totally undetected prior to entry. Why? Its approach was from sunward of Earth, where telescopes cannot see because of the daylight.

THAT is why I think planetary protection is not yet prioritized properly. While the probabilty is quite low, the consequences are simply unacceptable at all. Normal risk accounting does not apply, you simply have to do the risk reduction. Such a defense is an excellent justification for a space program. And not just unmanned, as eventually men are going to have to go to NEO's and comets, and characterize their cohesive properties better than any robot ever could.

GW

Last edited by GW Johnson (2018-10-25 09:31:46)

elderflower · 2018-10-25 11:47:26

I think the million tonne ones will probably be spotted early and nudged using railguns or light pressure. It is the ten thousand tonne ones, which might be 20 metres across (depending on density)that are of more concern because more difficult to spot and so more likely to need drastic, last minute action. And they could still obliterate a large area of a city, or cause a localised tsunami. Fortunately most of the earth's surface is not host to a major city.

GW Johnson · 2018-10-26 12:56:41

Given an improvement in detection capabilities that address the sunward threat as well as detecting the 10-m-class objects, what you say is true. Except it can never be true of comets, notwithstanding the few we have characterized orbits for.

I agree the probability of losing a city or a region to this threat is less than the probability of other threats we face. It's just that these outcomes are so untenable, one cannot dismiss the threat just because the probability is low. Yet politicians do that all the time.

I dunno about railguns and light pressure. What's been discussed at the planetary defense conferences is impactors and gravity tractors, with a grudging admission that nukes may be necessary as a last resort. Detection is still the dominant topic, though.

GW

SpaceNut · 2018-10-26 17:02:01

Light pressure or what is the solar wind would mean going and deploying a large sail to the object with the ability to change its shape to aid in tacking the objects direction. Even a little change with the help of engines to aid in the first good shove would make it possible to redirect the objects direction....

elderflower · 2018-10-27 05:50:34

Or painting one side of it, Spacenut. Perhaps with an advert...

SpaceNut · 2018-10-27 10:41:17

Why not add a lighted display message board saying I coming your way soon....

Yes a dark color would make it obsorb energy and white would be more reflective but does it change the wind force direction?

Void · 2018-10-27 11:55:33

You mention the wind.

What about a magnetic field also?

Which would interact with the solar wind.

Typical asteroids perhaps have magnetic minerals in them I might think. If you got to it soon enough, then a spacecraft with a magnetic field could use the solar wind to deviate the path of the object so that its modified path misses the Earth. The magnetic character of the would be impactor would also help the device cling to the object, provided it had sufficient materials that would be attracted to the magnetic field. In some cases the spin of the object could assist, as you could throttle the magnitude of the field as the object would spin.

So two energy sources, the solar wind and the spin of the object. And the tool to manipulate this being an artificial magnetic field.

Not to say that other methods could not be used in concert with this.

Done.

elderflower · 2018-10-28 05:11:28

Good thought, Void. Putting a coil around the target asteroid, powered by solar panels or a nuclear device might allow adjustment of the existing field. Since solar system space is permeated by magnetic fields from the Sun it might be possible to influence the orbit using this method. There might be issues with solar flares.

Mars_B4_Moon · 2022-06-27 06:16:11

"Asteroid spotting: Could an asteroid wipe out human civilisation like it may have eliminated the dinosaurs?

https://www.worksinprogress.co/issue/asteroid-spotting/

Mars_B4_Moon · 2022-07-30 18:17:10

'Impresionante Meteoro avistado en Puerto Rico'

https://www.sociedadastronomia.com/blog … nteMeteoro

Mars_B4_Moon · 2022-09-25 06:32:06

Protecting Earth from asteroids is complicated and requires global cooperation
https://www.space.com/asteroid-planetar … bal-effort
Detecting, tracking and stopping asteroids is a sprawling, interconnected effort.

Mars_B4_Moon · 2022-10-04 06:45:00

When Asteroids become Comets?

We are told the difference between asteroids and comets is their composition, as in, what they are made of. Asteroids are made up of metals and rocky material, while comets are made up of ice, dust and rocky material but the lines gets blurred and murky, some Comets have stony material while some Asteroids have ices or water material, so what was Dimorphos made of?

Meteor showers and where to see a Shooting stars? Perhaps something will arrive, on 4 October 2022 Didymos will make an Earth approach of 10.6 million km (6.6 million mi). The primary body of the binary system, Didymos, orbits the Sun at a distance of 1.0–2.3 AU once every 770 days (2 years and 1 month). Didymos I Dimorphos is a minor-planet moon of the near-Earth asteroid 65803 Didymos, with which it shares a binary system.

'After Getting Slammed by DART, Asteroid Dimorphos has Grown a Tail'

https://www.universetoday.com/157939/af … wn-a-tail/

Astronomers using the NSF’s NOIRLab’s SOAR telescope in Chile captured the vast plume of dust and debris blasted from the surface of the asteroid Dimorphos by NASA’s DART spacecraft when it impacted on 26 September 2022. In this image, the more than 10,000 kilometer long dust trail — the ejecta that has been pushed away by the Sun’s radiation pressure, not unlike the tail of a comet — can be seen stretching from the center to the right-hand edge of the field of view.
More images and details keep coming in about the asteroid intentionally smashed by NASA’s Double Asteroid Redirection Test (DART) spacecraft last week, and this latest image is stunning.
A telescope in Chile called SOAR took an image of the asteroid Dimorphos two days after the impact by DART and found the asteroid is trailing a stream of debris more than 10,000 kilometers (6,000 miles) long. However, other reports indicate that the debris trail could now be as long as 50,000 km (31,000 miles), and could still be growing.

Last edited by Mars_B4_Moon (2022-10-04 06:51:49)

Mars_B4_Moon · 2023-02-20 15:54:20

Planetary radar captures detailed view of oblong asteroid

https://www.spacedaily.com/reports/Plan … d_999.html

Mars_B4_Moon · 2023-03-10 05:29:00

On the first planetary defense test mission from planet Earth, the DART spacecraft captured this close-up on 26 September 2022, three seconds before slamming into the surface of asteroid moonlet Dimorphos.

https://apod.nasa.gov/apod/ap230309.html

DART vs Dimorphos

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#51 2018-10-24 09:37:48

Re: 2007 Planetary Defense Conference

#52 2018-10-25 04:59:31

Re: 2007 Planetary Defense Conference

#53 2018-10-25 09:28:02

Re: 2007 Planetary Defense Conference

#54 2018-10-25 11:47:26

Re: 2007 Planetary Defense Conference

#55 2018-10-26 12:56:41

Re: 2007 Planetary Defense Conference

#56 2018-10-26 17:02:01

Re: 2007 Planetary Defense Conference

#57 2018-10-27 05:50:34

Re: 2007 Planetary Defense Conference

#58 2018-10-27 10:41:17

Re: 2007 Planetary Defense Conference

#59 2018-10-27 11:55:33

Re: 2007 Planetary Defense Conference

#60 2018-10-28 05:11:28

Re: 2007 Planetary Defense Conference

#61 2022-06-27 06:16:11

Re: 2007 Planetary Defense Conference

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