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Thanks.
My name is Ed Lu,
and I'm building a space telescope,
together with the B612 Foundation.
(Applause)
It's called Sentinel,
and simply put, its mission is to protect the Earth.
In 2018 we're going to launch this thing,
and it's big, by the way,
it's about the size of a FedEx delivery van.
We're going to launch into an orbit around the Sun.
So it's going to be about 500,000 times further
from the Earth than the Hubble space telescope.
And we are going to find and track
threatening asteroids before they find us.
How'd we end up on this crazy quest,
other than the fact that everybody needs a space telescope?
Right?
Our organization started out about 10 years ago.
We started it with a different goal,
we were working with a different project, related.
And then something happened about a year and a half ago.
Interesting, a guy came up and asked me a question,
and it crystallized our thinking.
What we realized is that we had to change our course,
and that we had no choice but to actually do this, instead.
And I want to tell you the story
about how we ended up there and what we're doing.
Why should you care about asteroids?
Well, if you're a scientist, they're very, very interesting,
they're parts, left over parts of the solar system
from the formation of it.
But if you're a citizen of planet Earth,
and you all are, I hope,
(Laughter)
asteroids are important because they hit the Earth.
So if you roll this video,
anybody here has ever seen an asteroid impact site?
They're all over the Earth.
These are some of the known ones on planet Earth.
An awful lot, it's kind of a surprising lot?
But there's way more than this.
They hit the Earth all the time.
Just look up at the Moon.
The Moon is covered in craters,
and actually the Earth is hit more often than the Moon.
So the reason you don't actually see them on the Earth
is because they get covered up by the ocean,
or wind and weather, and things like that get rid of them.
They sometimes actually hit the Earth,
even in modern times.
1908 Tunguska, this is the aftermath.
It looks like a bunch of telephone poles laying on its side.
This is an impact site called Tunguska.
It's thankfully in Siberia,
where an asteroid, fairly small, about 40 meters across --
so I would say that's about the size of this room --
it hit in Siberia moving at a velocity
of about 20 kilometers per second.
Anybody here whoever took High School physics knows
that the energy is one half M V squared.
When you have a big number and you square it,
you get a huge number, and that was an enormous amount of energy.
It was about a thousand times larger
than the energy in the bomb dropped on Hiroshima.
So, it wiped out a huge area.
It's about 2,500 square kilometers of total destruction.
So, for example, just to put that in perspective,
if you drew a circle between
the Golden Gate Bridge and San Jose,
it took about that size.
That's the area that was wiped out.
Again, a thousand times larger than the Hiroshima bomb.
That was only 100 years ago.
These hit the Earth about every 100 to 200 years.
So, flip a coin, that's the odds that somewhere on Earth,
during your lifetime, it's going to happen again.
Random spot, most of the world's unpopulated,
but wouldn't it be a shame if it was a populated area?
(Laughter)
About 10 years ago, we decided that we'd work
on the problem of deflecting asteroids.
There was a bunch of really bad Hollywood movies out.
Armageddon, Deep Impact,
we thought we'd be the heroes,
we're going to figure out how to deflect an asteroid.
And if you roll this little movie,
over the last 10 years, we together with a lot of other scientists,
have worked on this problem, and now we understand
that it's actually not that difficult to deflect an asteroid.
What you have to do is either run into it with a spacecraft, like this,
and boom! You actually change the velocity slightly.
It's like playing billiards.
It turns out that with sufficient notice
you only need to change the velocity of an asteroid
by about a millimeter per second
to turn a hit into a miss,
if you do it early enough.
A millimeter per second. That's about this fast.
Okay? So you don't need to change the velocity a lot,
you don't need oil miners, and Bruce Willis, and stuff.
(Laughter)
It turns out that there are actually even controllable ways of doing this.
If we take the next video here.
This is something that me and another astronaut,
named Stan Love, yes he is Doctor Love, invented.
It's called a gravity tractor.
It's very, very simple. You just hover a spacecraft nearby,
and the mutual attraction of gravity between them,
very, very tiny, adds up and if you can hover for months,
so if you run this, you'll see that you can actually tow asteroids
and give them the required fraction of a millimeter per second
needed to precisely put this where you want.
What we realized after about 10 years of working on this,
and the community has realized,
is that deflecting asteroids is actually not that hard.
We actually have the technology to do things like this.
So what's the problem?
The problem is, if you don't know where asteroids are,
there's nothing you can do about it, right?
As my friend Don Yeomans likes to say,
"The 3 rules of deflecting asteroids are:
Find them early, find them early, and find them early."
So let's look at the big picture.
What does the Solar System look like?
If you could run this...
The green circle there is the orbit of the Earth,
and then you can see the orbits of the other planets.
And these are all the known asteroids,
and these are actual real positions. (audience murmuring)
The wizards at the California Academy of Sciences
put this together, these are real orbits.
All of this is real data,
those are the locations of all the known asteroids.
So the Earth again, look at the green line.
You see all the stuff flying around.
It's a very crowded place in our Solar System.
It's a little deceptive, because you have to make them bigger
so you can see it, but very, very crowded.
That's the good -- So here's the bad news, though.
We know what tiny area of the Solar System
we've actually surveyed thus far,
we know that it's not very much.
There's a hundred times more than you see here.
And those are undiscovered right now,
and we really have no way to discover them from the ground.
So what does the real Solar System look like?
Multiply this by 100 and you get what the real Solar System looks like,
it looks like this.
This is actually the situation --
follow the green line of the Earth,
and follow all the things that go whizzing past the Earth.
Every time you hear in the news
that an asteroid has whizzed past the Earth
you should think, "So what, it's happening all the time,
99 out of 100 we don't know about."
So that's what the situation looks like in the Solar System,
and that's what we want to change.
Because if you know where every single one of these is,
we can tell you where it's going.
Because we understand something called "Orbital Mechanics".
It turns out that if you tell me the velocity
and the location of each one of these things,
I'll tell you where it is any point out in the future.
Okay, that's how we send probes to Mars, for instance.
We ended up in a situation where
we know how to deflect asteroids,
but we're not looking for them.
We're driving around the Solar System with our eyes closed, essentially.
And that seems kind of crazy, right?
Because these things do hit the Earth,
as evidenced by this guy here.
As you all know, an asteroid impact is what wiped out the dinosaurs
and we don't want to be like him.
I saw a T-shirt the other day that said,
"Asteroids are nature's way of saying,
'How's that space program coming?'"
(Laughter)
So --
(Applause)
I was giving a talk about this very subject,
down in Mountain View at a large company
that rhymes with "Oogle".
(Laughter)
I was basically telling this whole sad story saying
we know how to deflect asteroids,
but basically nobody's funding,
the government has no plans, the government's broke anyhow,
and we're not looking for asteroids.
So the next large asteroid that hits the Earth
is in all likelihood just going to hit us and that will be what happens,
we'll take what we get,
but isn't it kind of crazy
that we actually know how to do this,
know how to deflect it, but we're not doing it?
And something interesting happened.
After the talk, a guy came up to me and he said --
I described that we actually knew how to
actually find all these asteroids too,
so you actually can't find them from the Earth.
You need to put a space telescope out,
orbiting around the Sun and so on.
And he said to me,
"How much does a space telescope like that cost?"
I said, "Well, they're expensive,
the government's not doing this,
it's $300 million, blah, blah, blah."
The guy looked at me and he said,
"So why don't you do it yourself?"
And I was taken aback.
"What do you mean, how can we do this?"
He goes,
"Well, I just donated money to
a museum in San Francisco,
the Museum of Modern Art.
We're building a new wing, we're supporting that.
We're raising more money than that.
We're going to build the wing of an art museum.
The people of San Francisco have come together.
In about 5 or 6 years,
we're going to do it, nobody has any doubt.
So if we can do that,
if we can build the wing of an art museum, for less money,
could you raise it and do it yourself?"
And I think the answer's yes.
So, we -- (Applause)
have gone out, we've been raising the money
and we've hired people and we're doing just that.
(Audience member) Thanks!
(Laughter)
You're welcome!
(Applause)
We just had our first major design review,
things are moving along.
And if you could run this video...
This is the spacecraft, it's called Sentinel.
Again, it's large, it weighs 2,630 pounds,
and it is going to orbit the Sun,
and it is going to view the Solar System in infrared.
Infrared is basically heat, where asteroids are bright,
and it is going to find these moving objects.
This is the view from Sentinel,
and it will see these moving objects and it will track them.
And it is going to discover each and every month,
over 10,000 asteroids.
Now all other telescopes combined throughout history
have sum total discovered about 10,000 asteroids.
So we're going to surpass that in month 1.
So what are we going to find?
We're going to find about a half a million asteroids when we're done,
and we're going to know where they all are,
where they're going, which ones are coming near Earth,
and which ones may actually threaten the Earth.
And that's plenty of time
to go out there and deflect them.
This is our plan.
So let me show you a little bit about why it has to be orbiting the Sun.
If you think about it,
you don't want to be on the Earth because you can't look --
half the time those things flying past the Earth
were between the Earth and the Sun,
and telescopes don't work very well pointing at the Sun.
So if you look at that white pie slice,
that is the view from the area that can be seen by Sentinel.
And you see that as it goes around the Sun,
it sweeps out an area
and it's sometimes on the opposite side of the Sun as the Earth,
and that is the trick to finding all these asteroids.
So again, 2018 is our launch date.
We've put together a team of folks,
and we're going to buy a rocket from SpaceX.
And we're going to put this thing out there,
and we're going to find all these asteroids.
So --
(Applause)
What's the big picture here?
I mean, to me the really cool part about this is,
that we're living in a really special time.
I mean civilization's about, what 10,000 years old, right?
10,000 years ago, people learned how to grow things,
agriculture and so on.
And here we are, 10,000 years later,
we have figured out the laws of orbital mechanics,
we've figured out rocketry, astronomy, mathematics, and so on,
and what's all that for, if it's not to protect the Earth, right,
if it's not to protect ourselves?
We actually know how --
we believe we know how to go out there
and measure our environment,
find out what's out there,
amongst all the stuff orbiting the Sun,
and protect our own planet,
and when something is on its way to hitting the Earth
to actually change the evolution of the Solar System.
So think about that, that's actually fairly, fairly amazing, right.
I mean --
hairless monkeys from the 3rd planet have figured out a way
to keep their planet from being struck again.
Okay, and we've only just reached this point,
and even more amazing to me
is that we've reached the point where --
because of advances in rocketry, and computing power,
and infrared detectors, and so on --
that we're actually at the point where
a private organization can just go do it.
Like that guy asked me, "Why don't you just go do it?"
The answer is, there's no reason why we shouldn't just go do it.
So here we are.
Thank you very much.
(Applause) (Cheering)
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【TEDx】Dr. Ed Lu :改變太陽能系統的過程 (Changing the course of the solar system: Dr. Ed Lu at TEDxMarin)

1537 分類 收藏
richardwang 發佈於 2014 年 3 月 24 日
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