(male #1)

The impact of

a 10-15 kilometer diameter



asteroid or comet

65 million years ago



would be the key event

in the cretaceous



tertiary boundary.



The event that caused

the extinction of the dinosaurs



is timing by geophysical

standards.



Either you can expect years

to decades of warning,



or it's gonna be

six or seven seconds.



(male #2)

This is an international

problem.



Who builds and executes

an operation on this?



And who gets blamed

when it doesn't work?



(male #3)

You send up a nuclear bomb

to make an inflection



of an asteroid in time

of emergency.



And then you find

it does nothing.



No matter where the next

big impact occurs,



we're all in big trouble.



(male announcer)

Planetary Defense, next.



[upbeat pop music]











(male #4)

The camera gave pictures

on all projected



at 60 times the speed

they were photographed.



1,120 kilometers to the moon.



576 kilometers to the moon.



Impact.



[boom]



(announcer)

Planetary Defense continues.



[ominous music]







Civilization is ill-prepared

for the inevitable.



It's not if an impact will

happen with the earth,



it's when.



[rumbling]



I don't know when I first

became interested in



the possibility of celestial

objects impacting on the earth.



But of course that

was the theme of



"Rendezvous with Rama."



And I'd like to read

the opening sentences.



"Sooner or later,

it was bound to happen.



"On June 30, 1908,

Moscow escaped destruction



"by three hours

and 4,000 kilometers



--a margin invisibly small by

the standards of the universe."



And I can jump forward

to the future.



"In the exceptionally beautiful

summer of the year 2077,



"most of the inhabitants

of Europe saw



a dazzling fireball appear

in the eastern sky."



And then I go on to describe

the destruction it created.



Well in "Rendezvous with Rama,"

I suggested the name



Spaceguard for an organization

to deal with this problem.



And I'm indeed happy

that when Congress



told NASA to look into this,

they published this



Spaceguard Survey.



"We call this proposed survey

the Spaceguard Survey,



"borrowing the name from the

similar projects suggested by



"science fiction author

Arthur Clarke



nearly 20 years ago

in 'Rendezvous with Rama.'"



Well it's now 30 years ago.



Of course, it's now generally

believed as a result



of the work by the late

Luis Alvarez,



with whom I was associated

during the war,



and in fact my

normal glide path



is dedicated to Luis.



Luis and his son Walter

were perhaps the first



to suggest that the dinosaurs

became extinct as a result



of a cometary impact.



And now some people think

that comets may have had



a great impact on the whole

early history of the world.



In fact, we may be here because

they wiped out the competition.



(male #5)

I think it's a,

it's significant that



a lot of people who have

thought about space



in important ways

like Carl Sagan,



Arthur C. Clarke,

many of these people.



We've had at this meeting,

Rusty Schweickart,



an Apollo 9 astronaut.



There's a number of other

astronauts, John Young,



who are very concerned

about the impact hazard.



I think the people have

a vision about space



and the earth's place

in space cannot help



but realize that we live

in this cosmic



shooting gallery

and we shouldn't be blind



to what actually had a

processes that have killed off



the species in the past.



I can't completely

fault the United Nations



with all the problems

on the 10 o'clock news,



high on the agenda.



(Moidel)

Well maybe not

high in the agenda,



but I would expect

some hype.



On the agenda.



On the agenda,

exactly.



I'm the Chairman

of the Association



of Space Explorers Committee

on Near Earth Objects



and the ASE took on the

challenge of dealing with



the international community

in trying to get



a decision process established.



So we're currently conducting

a series of international



workshops with a preeminent

group of international experts



who are, in the end,

out of those four workshops



going to draft in

the United Nations treaty



on NEO deflection.



And we're gonna be delivering

that for deliberation



to the United Nations

in the spring of 2009.



And that will be

the beginning of probably



an extended debate within

the United Nations



on how to deal with this.



But at least it will come in

in a neutral way,



not biased by any

national perspective



but from the stand point

of human protection,



protection of life

and property on the earth.



(Morrison)

The earth orbits the sun

within a swarm of asteroids.



And it is constantly subject

to a bombardment



of this cosmic material.



Over a very wide

range of sizes.



And the small impacts,

of course,



are much more frequent.



We can see them any night

if we go out under



clear, dark skies

and see the meteors



which are cosmic material

colliding with the earth.



All the way up to

the extremely rare events



such as the impact

65 million years ago



that produced the extinction

of the dinosaurs.



In between we can

estimate the frequency



with which these

impacts take place.



And, at least for the larger

ones, we can also estimate



what the effects

on the environment



and the ecology

of the earth would be.



Fortunately our atmosphere

protects us very effectively



from the great majority

of these impacts.



The meteors that produce

a flash of a shooting star



at night, all the way up

to giant bolides



which are occasionally viewed

passing through the atmosphere



and at night can light up

hundreds of square miles.



There are other bolides that

smash into the atmosphere



that are detected routinely 

by Department of Defense



surveillance satellites

that look down



on the atmosphere from above.



These things are happening

but because of the atmosphere,



they do us no harm whatever.



In fact, there's an atmospheric

explosion as big as



the Hiroshima nuclear bomb,

annually, on average,



maybe two or three times

a year sometimes.



We don't know about it.



We don't read about

it in the papers



because it's a very high

altitude explosion



and the energy is dissipated

at high altitude.



No shock wave

reaches the ground.



There are no bad

consequences whatever.



We simply exercise our

surveillance satellites



and observing these

in recording.



It's only when we reach

the larger objects



that the danger

becomes significant.



And, again, the nature

of the danger depends



very critically on

the size of the object.



The greatest danger,

the greatest risk



that we have today,

that the chances of it



will say on your tombstone

that you died from cause X,



is an impact by an asteroid

about two kilometers



in diameter.



Because that two kilometer

size, the impact it crosses



a threshold where the danger

is no longer local.



The damage just isn't

the blast, or the tsunami.



But the damage is done

to the earth's atmosphere



and to the environment

on a global scale.



It would be pretty,

very serious indeed, yes.



I think the way

to look at it is to say



Hiroshima was one-hundredth

of a megaton,



so the area of destruction

was a few square miles.



If you go up to a megaton

the area of destruction



is at the order of a hundred

square miles,



or something like that.



Tunguska was,

I think, 10 megatons.



So that would

have been plenty.



If it had, luckily it exploded

over forests in Siberia.



As far as we know

nobody was hurt.



(Morrison)

Since the mid '90s,

astronomers



had been searching

for these objects



in what we call

the Spaceguard Survey.



In 1998, NASA officially

accepted the challenge



of finding 90 percent

of the near earth asteroids,



bigger than one kilometer,

within ten years



that is by 2008.



And we are pretty well on track

today to achieve that.



(Worden)

There is a new generation

of ground-based optical sensors



where they'll be designed

to search the entire sky.



It turns out based on our

analyses that these systems



can be quite capable

for any old searches.



And indeed we think that much,

although certainly



not all of the things

in the scientific community



needs, could be done

in the next decade or two



with--by using these

sensors in a dual mode.



That's not to say

this will happen.



There's a lot of work

to be done between



the scientific community

and the Department of Defense



to make sure that these

agreements are in place.



(male #6)

The Torino scale was

designed to be a system



to inform the public about

newly discovered asteroids



and comets that might

come close to the earth.



And it's basically just

a simple ten point scale



where zero or one means

there's not really



very much risk at all,

it's simply an object



that we know is gonna

pass by the earth.



And ten is one as

a case where an object



is certainly going

to hit the earth



and cause immense

destruction.



There is still a bit of a,

what I call "giggle factor"



when you take this

to senior leadership.



I think we've made a lot

of progress on that



but there's still

more work to be done.



I have a lot of problems when

I go to a four star general



and say I wanna

do something here.



And he says, "When's the last

time we had an impact?"



And I say, "Well 65 million

years ago there was one."



And they tend to say that,

"Well if that's the last time



"we had one I think we can

probably postpone it



until next year's budget."



So I, again, emphasize

that it's not that we don't



need to focus on large objects,

but I think we need



to add a focus on a lot

of the smaller objects



which there is a much

more immediate concern.



(announcer)

Meet the Space Guardians when

Planetary Defense returns.











(announcer)

Planetary Defense continues.



(Worden)

I believe and I think

the growing intent



at least in the security

community, is the focus



for Planetary Defense

should be on small objects,



the sort of

10-500 meter objects



that for a variety of reasons,

I mentioned some of them,



but to add that

the most likely impact



in the next millennium

is clearly gonna be



a modest-size object.



LINEAR has been fairly

significant



with the LINEAR sensor

having discovered



the majority of

the near earth objects



particularly in recent years.



(announcer)

Lincoln Laboratory's LINEAR,

near White Sands, New Mexico,



is one of several

Spaceguard surveys.



(male #7)

The detection algorithms

that we're using



for the LINEAR program

were actually developed



for the Air Force for the

satellite surveillance mission,



that's finding earth-

orbiting satellites.



Now as you can imagine,

the Air Force



is very interested in high

probability of detection



of objects and

a low false alarm rate.



And, in fact, that

requirement extends



to a very cluttered

backgrounds.



As you see on this image,

this is data we've taken.



There's a single frame

in the Milky Way



where the star density

is in fact quite high.



What we're gonna now go through

is a process of finding



some objects in that very

cluttered background.



And this is typically an area

where the competing searches



and the astronomers

don't go anywhere near.



This shows a typical data

scene from the LINEAR system.



We've gathered this

with a CCD with about



a ten second exposure.



What you see here are quite

a large number of stars,



but in fact you can't tell

the asteroids from the stars



because this is

taken over a time



where the asteroids don't

have any apparent motion



on the screen.



What we have to do

to detect asteroids



is go back to the same

area five times over



a period of

two and a half hours.



That way the stars

stay stationary



and the asteroids

show some motion.



What we're gonna do now

is we're gonna start



going through and display

the five frames



that we've collected

over a period



of two and a half hours.



Okay, now we're stepping

through the five integrations



that we've taken

spread over that time,



now the algorithm is going

through the process



identifying the stars which

have not moved over that period



and then finding those

objects that have moved



over that period.



This is the result

of the algorithm.



What it's done is it's detected

all of the moving objects.



These that are little

short streaks



are main belt objects.



They move about

.1 degrees per day



and you'll see that

they're mostly aligned



in more or less

the same direction.



This object right

here is both going



a very different direction,

but it also has much more



motion over that period.



That's about

one degree per day.



And the fact that it has

a high rate of motion



that's very different

from the main belt,



indicates it is

a near earth asteroid.



And in fact this one is

designated 1998 QP



and represents a new discovery

for the LINEAR program.



(announcer)

There's another

project called NEAT,



Near Earth Asteroid Tracking,



run out of Jet Propulsion

Laboratory in California.



There is Spacewatch in 

Tucson, Arizona.



There's one in Flagstaff

at the Lowell Observatory



called LONEOS.



And one of the more prolific

ones with searches



in both the northern and

southern hemispheres



the Catalina Sky Survey.



Now these are the principle

search teams.



They're doing the vast majority

of the discoveries.



(male #8)

I've been doing

asteroid radar since 



the late 1970s,

which is a long time.



I've been doing it since

long before anyone



was concerned about asteroids

hitting the earth.



And for a long period of time

people thought I was crazy



to do that kind of work.



Now they don't.



Radar's a very different

kind of astronomical technique



that's erratically

different in terms



of the information you get

and the nature



of the experience.



There are only two places

you can do radar



on this planet,

Arecibo in Puerto Rico



and Goldstone in California.



And our best experiments

take advantage



of the unique capabilities

of each instrument.



Arecibo is very sensitive

but it cannot see



the whole sky.



Goldstone can see the whole sky

and is not quite



as sensitive so we usually

take data at both.



It's unlikely that we'd

be able to predict



a collision of an object

with the earth



using just optical data

anywhere near as far



in advance as we could

if we actually had



radar data.



So radar cannot tell

the chemical composition



but it can tell the density

of the surface.



And we've seen objects

that are very low density.



And we've seen objects

that are such high density



that they have to be metallic

because there's nothing else



that can be as dense.



So that's another kind

of information



that we get from radar.



(Steel)

We're so ignorant

of what's out there



and this is what

mitigation's about,



the current stage,

finding them,



and secondly characterizing

them either by



sending space craft there

or additional observations



using telescopes on the ground.



We need to know,

we need to know our enemy



is the first stage

of any war.



Know your enemy.



At the current stage,

we know we've got an enemy,



but we really don't know

his or her characteristics.



(male #9)

These objects,

comets and asteroids



have a nasty habit of running

into earth from time to time.



So if you find an object,

an asteroid or comet



with our name on it,

you certainly



would like to know

what it's made of,



how big it is,

how it's put together.



You'd have to know all

of these things before



you could effectively

mount a mitigation campaign



to deflect it.



(Yeomans)

The scientists feel that

the first step is to locate



the entire population,

or at least



a fair fraction of it and then

track them into the future.



And more than likely if there

is an asteroid out there



with our name on it

we'll know about it



10-20 years ahead of time.



And then that would

be enough time



to mount a mitigation campaign.



This is a problem that

really does not have



a coordinated response in

place yet, but there's time.



There's time to get

that response in place.



(Worden)

Military is, by nature,

confrontational



and it's, there's usually

two sides to every issue.



And so by putting one military

in sort of charge



that raises a very

significant issue.



Second is, you know,

I think undeserved



there's kind of a concern

in the scientific community



that military are up to some

sort of nefarious purposes.



So those are things

that need to be worked.



And this where the command

and control becomes



very important.



The who makes these decisions

and how does data flow,



that it's not gonna be turned

over to, you know,



General Worden

and Cheyenne Mountain



to make all

of these decisions.



And I think those are things

that we need to engage on.



But I clearly recognize

there is an issue there.



The first step is to get

the military,



the U.S. military

and other militaries



that have some capability here,

assigned a mission



to at least worry about it.



(male #10)

One day this is

going to happen.



It is for certain that

it will happen one day.



It might not be for another

10,000 years.



It might not be for another

100,000 years.



It could be next week.



All we know for sure is

that it is going to happen.



And I think that some,

we should be prepared



at some level

to deal with it.



(Morrison)

You know, they always say

you talk about the weather



but you can't do anything.



In this case, we cannot only

talk about the impact hazard,



it's within our capability

to do something



to really protect

the earth.



(announcer)

...when Planetary

Defense returns.











...continues.



(Morrison)

If we actually

found an asteroid



on a collision course,

we could predict the impact



decades in advance.



And we believe

we have the technology



in our space program

to deflect it,



so that the event

doesn't even happen.



I could study

earthquakes



all my life,

and I might be able



to improve my ability

to predict them,



but I could never 

develop a technology



to stop an earthquake

from happening.



In studying asteroids,

I not only have



the potential to predict

the next calamity,



but actually to avoid it.



(Harris)

To be honest, I wouldn't

be very confident



at the moment if

we were to discover



something coming at us

that was gonna collide



in twenty years' time...



I'd be very worried.



I'm not sure we could

do it with our present--



the present technology

available to us today.



(Morrison)

I would certainly admit,

as I think any scientist would



who's studying

asteroids and comets,



that we don't actually

know how to deflect one.



We don't really know

what technology we would use



to change the orbit.



All we can say is that

the orbital change acquired



is very small.



Take an asteroid

that is due to hit



a century from now

or 50 years from now,



and just change

its orbital speed



by a couple of

centimeters a second--



just the speed with which

I am moving my hand across.



That much change goes from

hitting the Earth



and producing

a terrible calamity



to missing the Earth

entirely.



And we need to study what

kind of space technology



is the best way to do it.



Is it using

nuclear explosives?



Is it something else?



(Harris)

A lot depends on

what the object is.



Is it a lump of metal?



Is it a rubble pile?



Is it a cometary nucleus?



And all of these

different things



would require

different techniques.



(Steel)

All these things are

still open questions



which we need

to answer,



and of course it comes

down to, you know, which--



what are the characteristics

of the one object



which is gonna be due

to hit you, you know.



If we had a choice, then I'd

hope that in fact it's gonna be



a solid nickel-iron object

like iron meteorites are,



because it's gonna

be strong,



and so you can deal with it

real roughly, you know.



So paradoxically,

you might say,



"Hey, I want a real

light one to hit us."



But I'd say, "No, I want

a real big dense one,



because it's gonna be easier

to deal with one of those."



The worse ones to deal with,

are going to be the things



which are rubble piles,

you know--



just accumulation

of debris in space,



which is held together

by its own gravity.



It's gonna come in 

and hit the Earth,



then it's gonna punch its way

through the atmosphere,



and it's gonna cause

as much damage as if it



were indeed solid.



The problem with

those is, you know,



they're real difficult

to deal with, you know,



in our imaginations

to push them around.



But we just don't know

at this current stage.



You know, we're so ignorant

of what's out there,



and this is what

mitigation is about



at the current stage:

finding them,



and secondly,

characterizing them,



either by sending

spacecraft there



or additional observations

using telescopes on the ground.



We need to know--

"we need to know our enemy"



is the first stage

in any war--



you know,

know your enemy.



At the current stage,

we know we've got an enemy,



but we really don't know

his or her characteristics.



(Harris)

It seems that

many asteroids



in the near-Earth

natural population



might actually be

piles of rubble.



By exploding

something like



a nuclear bomb

anywhere near it,



the energy will

simply be absorbed.



This is like punching

a bag of sand



or a beanbag

or something--



the energy is just

totally absorbed,



the object doesn't move.



There's very little

energy transferred



into momentum

to move the object.



In the case of

the rubble pile,



these original

traditional techniques



of sort of firing

an impactor or...



exploding something

just near the object



are unlikely to work.



(Belton)

All of the techniques

that have been talked about



over the last decade

for doing mitigation



probably won't work.



That went out by

a factor of 10 or 15



in our ability

to apply energy



to do deflations.



So we have to understand

this problem.



I mean, you're saying that

there'll be a nuclear bomb



to make a deflection

of an asteroid



in a time of emergency,

and then you



find it does nothing?



I mean, that's basically

the message that theorists are



putting before us.



So we have to go up there

and we have to start



trying to understand

how to make measurements



across the--not only

at the surface itself,



but deep in the interior.



And we don't know how to

do that right now.



So that's something new.



(male #11)

If you were interested

in deflecting an asteroid



or a comet that was

coming towards the Earth,



there's some point

you have to understand



the physical properties

of the asteroid:



what is its inside like?



All the little pieces--

is it one piece,



or is it many pieces?



How do all those

pieces fit together?



What happens if you

blow a bomb up next to it?



Is blowing up a bomb

a good idea,



or are you better off using

some more subtle means



of moving the asteroid away?



These kinds of

questions



could only be answered

if you understand



the interiors.



(Morrison)

I don't know how

to do it now,



but I do know that we can send

spacecraft to asteroids.



And NASA sent the NEAR

Shoemaker spacecraft



to a near-Earth

asteroid,



orbited it

for a year,



and even landed

on the surface.



We had that capability,

and if we knew



that we were having

to defend planet Earth



from an impact that

was going to happen



in 50 or 100 years,

we clearly would have



a very strong motivation

to actually develop



the technology to deflect it

and to save the planet.



(Harris)

The only thing that

might work in that



case is some sort of

propulsion system,



or something called

a mass driver,



which will apply

a relatively gentle force



to the object over

a long period of time.



You might be able

to do this also,



for instance,

with a solar sail--



that's another technique

that's talked about--



in which you mount

a great big sheet



of aluminum foil

or something similar--



a very reflective foil--

and attach that to



the asteroid,

and then by virtue of



the solar radiation,

this applies



a very, very gentle--

a very small force



to the solar sail.



And that force,

it turns out,



if you apply it

for a long enough time,



is sufficient--if you have

enough warning, of course,



if you have enough

lead-in time



before this object

hits the Earth--



that would be sufficient

to gently move it



out of its present

or current orbit



into another orbit that would

then just cause it to



pass by the Earth and not

collide with the Earth.



But I think there are certain

things up there that we'd have



a really difficult job

protecting ourselves from.



(announcer)

Decades of planning

are required,



and command and control

must be established,



when Planetary Defense returns.











...continues.



(Harris)

The whole thing

is very complicated,



because asteroids spin,

and so whichever way



you do this, however you

apply the force,



you've really got to

be very careful,



and you've got to think

carefully about how to do it.



(male #12)

Mission planning for landers

or sample return missions



is very problematic.



You can't put a lander--

you cannot put a passive lander



on the surface of one

of these monolithic



fast-rotating asteroids.



If you stick it

on the surface--



or I should say over

most of the surface--



the spacecraft will

just be tossed off.



The object is spinning too fast

to hold anything, all right?



It's spinning much faster--

in most cases,



these objects are

spinning much faster



than the critical limit

for strengthless bodies.



So anything you stick

on their surface



will just be thrown off.



That may include

regolith--



in fact, it probably

does include regolith.



We think these

are bare rocks.



So if your sample return

mechanism, for example,



is just a little scoop

or a little piece of Velcro



or I've heard a bunch

of other ideas



for passive sample

return mechanisms--



if you're just trying to

scoop up loose material



on the surface...

there isn't any



loose material

on the surface.



So, you have to both

have an active mechanism



for holding the spacecraft

to the surface,



and you have to have

a more active mechanism



for gathering your samples.



(male #13)

What's important

is what's your speed



relative to

the center of mass



in inertia space?



We've got an asteroid

that's rotating, okay,



and if you're walking

in one direction,



your speed is adding to

the speed that you have



just by sitting on

this asteroid.



And you're giving yourself

a greater speed,



and it might be

a large enough speed



to actually give you--

if you know orbital elements--



give you an apoapsis that's

above your current radius,



and that means that

you'd fly off.



If you walk in

the other direction,



you're actually

decreasing your speed



relative to inertia space.



You're rotating like this,

and if you walk



in that direction,

you're decreasing your speed,



so it's actually

a safer environment.



Rotating like this, you walk

in the same direction...



yep, yep.



(Moidel)

I see.



So it's--it's simple,

but it took me a while



to actually understand

that that could happen.



Once you see it,

it's, "Oh yeah,



that makes sense."



But that's part of the fun

things that you can imagine,



and which are of

practical relevance,



for trying to get around

on the surface of an asteroid



if we ever get

the chance to do that.



The main thing

we can do right now



with the technology

we have,



if we find a comet

that has a danger



of hitting the Earth,

is to send a spacecraft to it,



to do a reconnaissance

mission on it,



to search it out,

to...



see how big it is,

see what its mass is,



but most important,

to drop a transponder



into the asteroid.



When that happens, we would

then know its position



not this much,

but dead on.



We would know, if there's

going to be a collision,



exactly where on the Earth

it would collide.



Oh, this is very

well-developed



in standard technology,

so the actual transponder itself



would not be

a new development.



That's off the shelf,

practically.



But what is a new development

is the ability to put it there,



the environmental problems

of keeping it there



while it's spinning

around on an asteroid,



which may be spinning

so fast that it wants to



throw it right off,

or who knows what.



So developing the ability

to actually go there,



land, and attach

a transponder is...



is the technology

that'll drive it.



(Belton)

Future technologies--

I feel very, very strongly



that in the business

of space exploration



and understanding

the scientific requirements



for mitigation,

that we're going to



have to fly missions that

have been quite different



from what we've seen

in the past.



This business of

acquiring tomography,



which is done routinely

on the Earth, you know,



in hospitals

and so forth,



is not really being

applied in space.



And that will be

a big deal,



because the data

implications as well as



the instrumental applications

are quite substantial.



The other thing is

that it's pretty clear



that the whole business

of exploring NEOs



will require some kind

of probable contact



between the experiments

and the objects.



I mean, seismology,

for example,



looks like it could be

a key element.



But we'll actually

have to take into space



some kind of grenades

or explosives and so forth,



and that's never been done

in a science program before.



I think for this decade

we need to put in place



the comprehensive

all-sky surveys



that go down

to the, you know,



eventually 22nd,

23rd magnitude.



And that would culminate,

in my opinion,



probably 15,

20 years from now



in some attempts

to move some of these--



you know, to do

demonstrations--but yes,



I'd say 20 years

before we get



a comprehensive

capability.



(Schweickart)

Okay, I'm

Rusty Schweickart,



and I'm Chairman of

B612 Foundation,



Chairman of the Board

of the B612.



We formed

the organization



in order to try

and foster



the development of

the deflection capability.



We set a goal, which was

to significantly alter



the orbit of an asteroid

in a controlled manner



by 2015.



There's no need to

de-spin the asteroid



in the case of

the gravitational tractor,



because the gravitational

tractor never touches



the asteroid.



All you have to do is

make sure that it doesn't



wipe you out as you're

hovering above it,



because it's potato shaped

or something of that kind.



So you have a challenge

in hovering over something



that is unusually shaped,

non-spherically shaped,



and rotating randomly

beneath you.



(Worden)

Command and control.



This is probably

something most of you



aren't familiar with.



And most of the discussions

of mitigation are in the--



are in the mode of

what kind of weapon



that we're gonna use,

or means to divert



an object

or to mitigate it.



I would like to submit

that as the community



becomes very serious

about this,



both nationally

and internationally,



you're gonna need to focus

as much if not more attention



on command and control.



A lot of issues here--

you know,



who's responsible for

identifying the threat?



You know, who assesses

whether it's real, and why?



You know, who tells whom

about this threat--



who's the one that--

in power to do this?



And who decides

what to do?



And then who builds

and executes



an operation on this?



Maybe most important,

who pays for it?



And who coordinates...



with all of

the affected parties,



and who tests

this thing?



I mean, you're not gonna do

something without testing it.



And also very important,

who gets blamed



when it doesn't work?



(Steel)

We've gotta think about

the whole of the planet.



No matter where

the next big impact occurs,



we're all in big trouble.



(announcer)

...when Planetary

Defense returns.











...continues.



(Ostro)

With comets, all bets for

comfortable warning are off.



And we can't imagine

how we would be able



to defend ourselves

from a comet--



a long-period

comet impact.



(male #14)

The real distribution

of comets at



the small perihelion

distances--



ones that could potentially

be hazardous--



is very poorly known.



The size distribution is also

almost totally unknown,



because there are so few

nuclei for which we have



been able to measure

a reliable size--



it's largely because

the nucleus is hidden



in the coma of

dust and gas.



(Worden)

Also point out that

there are classes of objects,



particularly comets,

that you're probably



not gonna detect--

surprise objects.



They're hard,

and they're likely



to be more of

the rubble pile



or difficult objects

to move.



(Ostro)

So to protect ourselves

from the long-period



comet component

of impact hazard,



we need a warning system

that's way out of the orbit



of Neptune, at least.



Probably maybe even

beyond that--



something with super-sensitive

infrared detectors



that can observe

these comets



years before they get close

to the inner solar system.



So we need a reconnaissance

system that's way beyond



anything we're likely to have

in this century, I believe.



And then we need

a mitigation system



that is way off at

the deep end of scenarios



for protecting ourselves

from incoming objects.



Very scary, so that's

the dread of one part of



asteroid/comet

impact hazard.



And the possibility

of us being done in



by such an object is down

orders of magnitude



from the asteroid

threat itself.



So this is

highly unlikely,



but it's also inevitable.



(Moidel)

It seems very troubling.



I mean, you look at

a long-period comet hazard,



and you say it's probably

one of the most dangerous.



It's hardest to spot.



They're comin' in fast.



They're big...



And you can't do

anything about them.



They're

least likely...



They're least likely.



But you said earlier

they're inevitable.



They're inevitable over

a very long time scale.



Now the question is...

you know, does that



such a--is that

time scale so long,



and the probability of

having to do anything--



having to worry

about them really so low,



that we shouldn't

worry about them at all?



And maybe the answer

is yes,



we should not worry

about them at all.



The chances of having

an impact of the sort



that wiped out

the dinosaurs



happening--

I mean, it's remote.



But it's not impossible.



Comet Hale-Bopp,

that came by a few years ago



in the sky,

came out of



the far-away darkness

of the outer solar system



and passed inside

the Earth's orbit--



happened to be on the other

side of the Sun,



but the comet was still

pretty bright in the sky.



It was a big comet.



It was enormous.



It was certainly larger

than the impact that



wiped out the dinosaurs--

and it came without warning.



(Ostro)

The long-period comets

may be the limiting factor



to the longevity

of human civilization,



which is highly ironic

and interesting because



the long-period comets--

the comets, of course,



are partially responsible

for the origin of life itself,



and it's these

mass extinctions



over history that

have punctuated



the evolutionary process

that led to the existence



of intelligent life

on this planet.



So some of us who have

thought this through



and have blurred

the line between



science and futuristic thinking

and science fiction



have concluded that...



these long-period comets,

the impact hazard itself--



which is partially

responsible for



our origin

and our evolution--



will also provide

the pressure for us



to evolve into

a space-faring entity.



And really,

ultimately,



either intelligent

civilizations become extinct,



or they become

space-faring.



So as not to leave

all your eggs

in one basket?



Yes.



So it all depends just how

dispersed they are.



If you have all your

eggs in one basket,



then you'll have to worry.



So basically,

either something's



coming at us and we

don't know about it



and it'll be over

in seven seconds,



or we have a lot

of time to prepare.



Exactly.



The situation

really divides



depending on the level

of our knowledge.



For those we have

not discovered,



we'll have no

warning at all,



or five seconds' warning.



The first thing you'll know

is when the sky lights up.



If you do discover,

if it does come out



of one of these surveys,

then you can predict



its orbit precisely

for many decades,



and you will have

very long warning.



Either you will have

plenty of warning



so that you can develop

a mitigation strategy,



or else you'll be taken unawares

just like the dinosaurs.



(Clarke)

There's--a meteorite did

fall here in Sri Lanka



a few weeks ago,

and one about this big...



even though it

didn't do any harm,



and most of them,

of course, don't.



But one day, a big one

will go into some



inhabited neighborhood

and there's no saying



what damage it may do.



I'd like to end

by a quotation



which I'm always using;

I think one of



my fellow science fiction

writers made it.



"The dinosaurs

became extinct



because they didn't

have a space program."



Thank you--

this is Arthur Clarke



saying goodbye

from Colombo.



[clock ticking]







(radio)

Okay.



People should be aware

that there is a new



or a revised

Spaceguard Survey goal.



In 1998, the Congress

set up a goal



which was to discover

90 percent of all



the near-Earth objects

larger than one kilometer



over a period of ten years.



However, in December

of 2005,



the authorization bill for

NASA passed by the Congress



included a revised goal,

and so now NASA



is charged with discovering

90 percent of the NEOs



140 meters and larger

over the next 15 years--



in other words,

by 2020.



(Yeomans)

Certainly for

the larger objects,



the most cost-effective

way to find them



is to use Earth-based

telescopes.



At some point, when you start

asking the question



how do you best discover

the 100 meter sized objects,



the 200 meter

sized objects...



at some point it might

make sense to go to



a space-based system

that is located



interior to the Earth's orbit

so that it's looking out



at objects that can get

close to Earth.



(Steel)

It's no way to, you know,

defend the planet,



is having a group of people,

a very loose group,



who are doing it

out of goodwill



spread around the world.



It really needs a major

international program.



It's just not happening.



(male #9)

The military has only recently

awakened to this notion.



For a while, it received

a few giggles in the corridors



of the Pentagon,

but now it's being received



far more seriously,

and I suspect they'll



have a plan in place

before too long.



(Worden)

The majority of the data

that has been taken



and will be taken

in the future on NEOs



is very likely to be taken

by national security sensors.



The key here is to have

this mission assigned to



the Department of Defense;

that has not been done,



and that's a fairly long

and complicated process.



We also need to work this

very closely with NASA



to ensure that the interfaces

maximize the benefit,



not only for our

warning concerns,



but also for

the scientific community



to have access

to the data.



We expect by the end of this

decade to have a series of--



it could be as many

as six satellites



that'll be designed

to survey, from space,



the entire sky.



These will not go very deep

in terms of brightness,



but they do offer

the ability, potentially,



to survey every few hours

all of space.



When you're particularly

looking at very small objects



that could come in

very quickly,



in the tens of meters class,

this type of system



could be very, very useful.



And I wanna note this is

not just the United States;



the Canadian Department

of National Defense



is also building something

called Sapphire,



which is a space-based

space surveillance system.



So I'd like to note that

the community needs to--



to look very carefully

at how we might use



these space-based systems.



(Yeomans)

What do we need to do

to understand



comets and asteroids

so that if one is on



an Earth-threatening

trajectory,



we have

the knowledge to...



and the technology

to deflect it.



(Ostro)

To get to the point

where someone could say,



"Well, long-period

comet impact,



"we don't need any

new technology,



"we don't need any

new science,



"we'll have enough warning,

we just have to



make the commitment"--

we will not get



to that point

in this century.



(Harris)

To be honest, I wouldn't be

very confident at the moment



if we were to discover

something coming at us



that was gonna collide

in twenty years' time...



I'd be very worried.



I'm not sure we could

do it with our present--



the present technology

available to us today.



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