The QE2

[alter-ego]

can someone direct me to an article that explains why the Earth won't try to steal the little satelite away from the asteroid when it flies by?

The Earth pulls almost equally on QE2 and its satellite.

The L₁ Lagrangian point: is about 800 kilometers above the surface of QE2 such that the satellite would have to orbit at least that high above QE2 for the Earth to have a chance to steal it away.

What about just changing its orbit rather than stealing it?

• Maybe 400 km.

Upon reconsideration: the tidal effects by the Earth on the satellite are much less than I originally thought.

This is because tidal effects by the Earth are:

• 1) on average, perpendicular to the satellite velocity (and, hence, ineffective)
  2) of a fleeting duration much shorter than the L₁ satellite period (~4.5 years in this case).

Hence, any satellite of an Earth grazing asteroid must be many L₁ distances away to be affected.

Just to establish a reference point from the radar images, I made a crude estimate for the moons orbital radius (upper bound) and orbital period. Assuming QE2 is a sphere 2.7km in diameter with a density ≈ 3g/cm³, I get an orbital radius ≈ 22km and a period ≈ 5 days.
The radar data actually describes a projected view the orbital plane wrt Earth, i.e. it is most likely inclined from our perspective. I assumed the orbital plane is not inclined, and the moon's motion was directly toward Earth. Therefore the true orbital velocity can only be larger than what I estimate, which in turn means a smaller radius and shorter period. As I said this is very rough estimate.

As suggested earlier for a moon rotation that's locked to the orbital period (Doppler data), then the orbital period ≈ 2 days. This shorter period is well in line with expectation and my estimate's uncertainty.

[Ludo]

Is Earth possibly intelligent because it is small enough to not be pulling these errant rocks into it "as often" as larger Earths might be able to do? Would a super Earth always be attracting large destructive rocks to it so often or regularly that intelligence would have trouble developing to the math and physics teacher level.

As I see it, if you increase the scale of our planet so would you be increasing the scale of the easily deal meteors that have slight to no impact on our surface. You would also have to increase the scale of neighbouring planets for your own to be protected by them. So, having a "Super Earth" would still require a "Super Jupiter" (and others respectively) to keep super meteors and super comets at bay (but I'm just an amateur, I could be seeing it wrongly).

[neufer]

Just to establish a reference point from the radar images, I made a crude estimate for the moons orbital radius (upper bound) and orbital period. Assuming QE2 is a sphere 2.7km in diameter with a density ≈ 3g/cm³, I get an orbital radius ≈ 22km and a period ≈ 5 days.
The radar data actually describes a projected view the orbital plane wrt Earth, i.e. it is most likely inclined from our perspective. I assumed the orbital plane is not inclined, and the moon's motion was directly toward Earth. Therefore the true orbital velocity can only be larger than what I estimate, which in turn means a smaller radius and shorter period. As I said this is very rough estimate.

As suggested earlier for a moon rotation that's locked to the orbital period (Doppler data), then the orbital period ≈ 2 days. This shorter period is well in line with expectation and my estimate's uncertainty.

I concur with your calculation assuming the total duration of this sequence is ~72 minutes or ~30% of a full rotation. However, you could well have overestimated the density by a factor of ~2 or more which would reduce the orbital radius => 11km and period => 2.5 days. This seems somewhat more reasonable considering the 2-3 pixel Doppler width of the satellite.

[alter-ego]

Just to establish a reference point from the radar images, I made a crude estimate for the moons orbital radius (upper bound) and orbital period. Assuming QE2 is a sphere 2.7km in diameter with a density ≈ 3g/cm³, I get an orbital radius ≈ 22km and a period ≈ 5 days.
The radar data actually describes a projected view the orbital plane wrt Earth, i.e. it is most likely inclined from our perspective. I assumed the orbital plane is not inclined, and the moon's motion was directly toward Earth. Therefore the true orbital velocity can only be larger than what I estimate, which in turn means a smaller radius and shorter period. As I said this is very rough estimate.

As suggested earlier for a moon rotation that's locked to the orbital period (Doppler data), then the orbital period ≈ 2 days. This shorter period is well in line with expectation and my estimate's uncertainty.

I concur with your calculation assuming the total duration of this sequence is ~72 minutes or ~30% of a full rotation. However, you could well have overestimated the density by a factor of ~2 or more which would reduce the orbital radius => 11km and period => 2.5 days. This seems somewhat more reasonable considering the 2-3 pixel Doppler width of the satellite.

Yes. This calculation was meant to get a ballpark-level understanding.

The density choice I picked is for a carbonaceous chondrite-type asteroids, maybe not the right density. I'm still most suspect about what the actual velocity is. The measured orbital component ≈ 0.3 m/s, and could easily be 0.45 m/s (say 45° inclination angle) which would put it at 11km radius (without changing density). But I certainly agree with you that my chosen density is likely not correct. My bet is that all my assumed parameters are off.

The Doppler-based rotation estimate for the satellite assumes an inclination for the rotation axis also. In the extreme case (also not likely) if the rotation axis was pointed at Earth, there also would be no Doppler shift and would appear in the images as a single-pixel wide source. However, for a tidally-locked case, I guess the satellite's rotation axis would be nominally parallel to the primary's rotation axis, which is the assumed case for the Doppler width calculation.

Correction: In the last sentence, I meant to say that the satellite's rotation axis would nominally be perpendicular to the orbital plane.

[Czerno 1]

Yes...but don't forget that math and physics teachers wouldn't be here if an asteroid hadn't wiped out the dinosaurs.

After some hundred mega-years, possibly dinosaurs would have spawned math and physics teachers. Including one dino called Newton, or one Einstein. Who can tell ?

Cheers, Artie pal !

--
Czernosaur

[rstevenson]

After some hundred mega-years, possibly dinosaurs would have spawned math and physics teachers. Including one dino called Newton, or one Einstein. Who can tell ?

The dinosaurs lived for about 165 million years. They've been gone for about 65 million years. So "we" have had 100 million fewer years to develop, and still we managed a Newton and an Einstein. Seems to me they had their chance to see how thinking would work out, and they chose other paths.

However, I've often wondered if they did in fact travel some way along the path towards thinking, and were just knocked down at the wrong moment by whatever killed them. They could have come all the way to early forms of agriculture without leaving any evidence that would survive for 65 million years.

Rob

[Chris Peterson]

The dinosaurs lived for about 165 million years. They've been gone for about 65 million years. So "we" have had 100 million fewer years to develop, and still we managed a Newton and an Einstein. Seems to me they had their chance to see how thinking would work out, and they chose other paths.

Simple observation of the world demonstrates that "thinking" isn't a particularly useful skill, and far more species have done much better without it than we have with it.

[rstevenson]

Simple observation of the world demonstrates that "thinking" isn't a particularly useful skill, and far more species have done much better without it than we have with it.

Depending, I think, on your definitions of "useful skill" and "better".

I'm an odd combination of cynic and optimist. I'm cynical about the short-term behaviour of small groups of humans, but optimistic about our long-term prospects as a race. And for those long-term prospects, thinking is not only useful, it's vital. We're just not as good at it, yet, as we need to be. (Note that I'm talking about long-term prospects. Getting there will require surviving some risky times, for sure, and there's no guarantee we'll manage it.)

Rob

[mjimih]

http://dinosaurs.about.com/od/dinosaurb ... smarts.htm
How Smart Were Dinosaurs?

Could Dinosaurs Have Evolved Intelligence?

It's easy, from our present-day perspective, to poke fun at walnut-brained dinosaurs that lived tens of million of years ago. However, you should bear in mind that the proto-humans of 5 or 6 million years ago weren't exactly Einsteins, either--though, as stated above, they were significantly smarter than the other creatures in their ecosystems.

This raises the question: what if at least some dinosaur species had survived the K/T extinction 65 million years ago? Dale Russell, the curator of vertebrate fossils at the National Museum of Canada, has caused a stir with his speculation that Troodon--a human-sized theropod dinosaur about as smart as an opossum--might eventually have evolved a human-sized brain if it had been left to evolve for another few million years.

This is just amusing speculation, of course; for one thing, the whole question of brain size also depends crucially on metabolism. If the dinosaurs were indeed cold-blooded, there's no question that they would have had to evolve a warm-blooded metabolism to proceed on the march to intelligence--and even if they were already warm-blooded, their low EQs meant they had a lot of catching up to do.

Click to play embedded YouTube video.

[mjimih]

I'm an odd combination of cynic and optimist. I'm cynical about the short-term behaviour of small groups of humans, but optimistic about our long-term prospects as a race. And for those long-term prospects, thinking is not only useful, it's vital. We're just not as good at it, yet, as we need to be. (Note that I'm talking about long-term prospects. Getting there will require surviving some risky times, for sure, and there's no guarantee we'll manage it.)

Rob

The QE2 has definitely brought out the smart in this thread. From how an asteroid satellite behaves near Earth to how smart dinosaurs might have been. Unfortunately unless compassion and facts rule the political world and not ideology n greed, and we all learn to vote for reason not money, we might as well wait for a "dumb" rock to come by and scare us into reasoning together for the common good, to discover survival techniques in an over crowded world, like we should, so we can successfully fight off the inevitable bad days ahead.

Mark

[neufer]

---

The dinosaurs lived for about 165 million years. They've been gone for about 65 million years. So "we" have had 100 million fewer years to develop, and still we managed a Newton and an Einstein. Seems to me they had their chance to see how thinking would work out, and they chose other paths.

Simple observation of the world demonstrates that "thinking" isn't a particularly useful skill, and far more species have done much better without it than we have with it.

"Communicating" is always a useful skill,
however, even for bees, ants & slime mold.

[geckzilla]

But communication doesn't necessarily involve thinking. If thinking helped us successfully procreate, then I guess we'd see more and more Einsteins. Instead, the opposite seems to happen.

[BMAONE23]

After some hundred mega-years, possibly dinosaurs would have spawned math and physics teachers. Including one dino called Newton, or one Einstein. Who can tell ?

The dinosaurs lived for about 165 million years. They've been gone for about 65 million years. So "we" have had 100 million fewer years to develop, and still we managed a Newton and an Einstein. Seems to me they had their chance to see how thinking would work out, and they chose other paths.

However, I've often wondered if they did in fact travel some way along the path towards thinking, and were just knocked down at the wrong moment by whatever killed them. They could have come all the way to early forms of agriculture without leaving any evidence that would survive for 65 million years.

Rob

Click to play embedded YouTube video.

Click to play embedded YouTube video.

[stephen63]

But communication doesn't necessarily involve thinking. If thinking helped us successfully procreate, then I guess we'd see more and more Einsteins. Instead, the opposite seems to happen.

Our advanced state of social evolution?

[Rhysy]

Well, this one doesn't have any dinosaurs in it at all, but it does have 1998QE2, its moon, and a space station.

http://zoom.it/l3ue

[geckzilla]

We drop all the bad Asteriskians at QE2 and make them run laps around it until they feel sorry. Then we let them back. It's probably hard to run around the moon without jumping off it.

[bystander]

junk.jpg

Well, I don't know who the person is on the right, but I don't know all the people on the left, either. Who is top right next to Carl Sagan?

[Chris Peterson]

junk.jpg

Well, I don't know who the person is on the right, but I don't know all the people on the left, either. Who is top right next to Carl Sagan?

That's Ayaan Hirsi Ali, an anti-Islamic atheist activist. Top to bottom, left to right:
Hawking, Curie, Tesla
Einstein, Freud
Ali, Paine, Hitchins
Sagan, Darwin.

A who's who of modern thinkers (and atheists- I guess the left side might have come from an atheist site).

And on the right, someone called Snooki (I semi-guessed that one... thought it might be a Kardassian). Someone famous for nothing more than being famous.

[geckzilla]

An atheist site would have included a nice, big photo of Dawkins. And Darwin was firmly agnostic iirc.

[stephen63]

After careful consideration, I had to bump Christopher Hitchens

[Chris Peterson]

An atheist site would have included a nice, big photo of Dawkins. And Darwin was firmly agnostic iirc.

I don't consider there to be any practical difference. In a philosophy classroom, agnostics could either be theists or atheists.

As far as Darwin is concerned, he went from Christian earlier in his life to pretty much what most would call atheism by the end. The other special cases might be Curie, whose specific religious views I've not read about, but who avoided religious ceremony, and Paine, who was deist (a good case can be made equating Age of Enlightenment deism to modern atheism). In any case, this is a collection of faces I wouldn't be surprised to find on an atheism oriented site. With Hitchins up there, they might not have felt it necessary to include Dawkins. As it is, the group is quite diverse.

[geckzilla]

True, I think Darwin saw it that way. Still, I don't think he would have liked being paraded around as one of the poster children for atheism but that doesn't mean that they don't do it. Also, try to tell someone who's agnostic that they are atheist and they will most likely take exception to it. Anyone I've ever asked why they are agnostic and not atheist has always seen a big difference in the two.

Shutting up now because I am precariously close to breaking one of the forum rules. Sorry, bystander!

[neufer]

We drop all the bad Asteriskians at QE2 and make them run laps around it until they feel sorry.

Then we let them back. It's probably hard to run around the moon without jumping off it.

The general rule of thumb is: If you can run around the object in 2 hours you are essentially in orbit and you could easily sprint into space if you so desired. QE2 is 5.3 miles in circumference.

[mjimih]

you might need a pair of these 6% off while supplies last

http://www.ebay.com/itm/Nasa-Space-Shut ... 1020565884

[alter-ego]

Just to establish a reference point from the radar images, I made a crude estimate for the moons orbital radius (upper bound) and orbital period. Assuming QE2 is a sphere 2.7km in diameter with a density ≈ 3g/cm³, I get an orbital radius ≈ 22km and a period ≈ 5 days.
The radar data actually describes a projected view the orbital plane wrt Earth, i.e. it is most likely inclined from our perspective. I assumed the orbital plane is not inclined, and the moon's motion was directly toward Earth. Therefore the true orbital velocity can only be larger than what I estimate, which in turn means a smaller radius and shorter period. As I said this is very rough estimate.

As suggested earlier for a moon rotation that's locked to the orbital period (Doppler data), then the orbital period ≈ 2 days. This shorter period is well in line with expectation and my estimate's uncertainty.

I concur with your calculation assuming the total duration of this sequence is ~72 minutes or ~30% of a full rotation. However, you could well have overestimated the density by a factor of ~2 or more which would reduce the orbital radius => 11km and period => 2.5 days. This seems somewhat more reasonable considering the 2-3 pixel Doppler width of the satellite.

Well the new results are in after more radar measurements, and your inclination towards a lower density was correct, but surprisingly, still ~2x too high!
The orbital period and "maximum" radius are listed as 32hr and 6.4km respectively, which sets QE2's density ≤ 1gm/cm³. A fluffy asteroid indeed! I was expecting both a lower density and faster orbital velocity than my original calculations, but it turns out the new velocity is about the same (only 9% faster) which means the density is much lower. If this density is correct, it must be a record holder. (Mathilde density = 1.3gm/cm³)