The Greening of Orbital Debris (Nicholas Johnson)

Uploaded by NASAappel on 01.09.2011

It turns out that because of my activities I deal with engineers
probably more than any other type of discipline
not only within the Agency
but within the inter-agency the U.S. government
and internationally.
And someday if my granddaughter
decides to marry an engineer,
I"ll probably give her my blessing.
Um, this will automatically go.
Prior to Sputnik I
there was only one known object
in orbit about the earth
and that of course was the moon.
Since then,
we've gotten quite a bit of man-made debris.
It turns out that throughout the past 50 years
the percent of operational objects in earth orbit
is about five percent.
It's maintained that pretty regularly
up until the last few years.
One of the challenges I do not have
is when I show this series of slides at the end
everybody agrees
there is a space pollution problem.
It's not like climate change
where there's still debate, whether you...
you think there is a legitimate debate or not
there is an actual debate
and you have to convince people.
This pretty much convinces them
all by itself.
So these are all objects
which are larger than ten centimeters
which are being tracked on a regular basis
by the U.S. Space Surveillance Network.
I do have to make a caveat:
for obvious reasons
the dots are not to scale to the earth.
[audience laughter]
And when I first started putting these
charts together about 30 years ago,
I picked the size of the spot
to be a little bit bigger than the
classic little dot you get
on a bad Xerox in the old days.
But what this does, so,
it looks like it's more congested than it really is.
Space is a big place.
And even though there
are lots of particles out there
and millions spacial density,
the number of pieces per cubic kilometer,
it's still very very low.
I mean we don't lose
operational space craft very often
with the exception of this year
to space debris, which is a good thing.
But these kind of graphics
are useful in looking at
the areas of concentration, and the
the trends that we see.
This is one of my favorite cartoons on orbital debris.
You know you've made the big time if
Frank & Ernest talk about your discipline.
The other interesting aspect is
this cartoon actually is over 25 years old.
Space debris, orbital debris,
has been in the public consciousness
for a long time.
It's obviously not something they
worry about on a daily basis,
but when certain events happen
like the satellite collision in
February of this year,
then people pop up and say
"Oh yeah, I knew something about that."
So what is orbital debris?
It's a pretty simple definition
it's anything which is not useful
and in earth orbit.
So that means derelict space craft,
it means orbital stages for launch vehicles,
and it means lots of fragmentation debris
and things which we intentionally
threw off a space craft
be it during human space flight
or be it during
robotic operations.
Some of this debris, some of the stages
are up to eight metric tons--a piece.
Some of these debris of course
are, you know, less than a gram.
So, we have to worry about that.
This is a
history of the official catalog that the
U.S. maintains of objects in Space
So this is sort of a graphical synopsis of those
pictures you saw at the very beginning
and we've broken them out into
rocket bodies, pay-loads, mission-related debris
things we threw off intentionally
and fragmentation debris.
And fragmentation debris has always been
the largest share of the overall population
we've had two major events since 2007:
The Chinese conducted an anti-satellite test
which instantaneously
contributed over 3,000 large objects
3,000 objects larger than ten centimeters
so a dramatic jump in the population
which we had been building over 50 years
and all of a sudden we have this great step function.
And then,
the accidental collision between an
Iridium spacecraft and a Cosmos spacecraft
in February of this year,
which instantaneously created about
2,000 large objects.
So just very briefly, um...
the conditions, the background for that collision:
It occurred in February of this year
and out to about 790 kilometers.
That was not an accident.
790 kilometers, 800 kilometers
is like the second highest concentration
of tracked objects, or...
objects in general in orbit about the earth.
So if you're looking for an accidental collision
you know statistically they're going to happen
where you have the most objects.
And it finally did happen.
We've actually had accidental collisions
prior to this, but never between
two large intact objects.
The accidental collisions we've had prior
were between a small object
and a large object,
and spacecraft or a rocket body
and very little debris was produced.
In this case, both of the spacecraft
were substantially destroyed
in terms of numbers of pieces.
And we're still counting.
I mean this chart says 1,700
it's getting close to 2,000
and those are just the big things.
The smallest debris, of course,
goes up exponentially.
We've already,
NASA has already had to do one
collision avoidance maneuver
with one of our robotic spacecraft
because of debris from this collision.
Actually just a couple of weeks ago,
we were preparing to maneuver the
International Space Station
away from debris from this collision
but the last few hours
before we executed that maneuver
we decided well it wasn't going to come quite so close
and did not meet our risk threshold
for actually conducting the maneuver
so we stood down.
Debris is dynamic
just like the environment itself
in that it doesn't stay in one place.
Initially what you have
when you have a collision anyway
you have two distinct clouds
it just turns out that
these two vehicles when they hit
were almost in perpendicular orbits
had a collision velocity of nearly
11 kilometers per second
which is why you have so much energy
and why you have so many pieces.
But the perturbations in orbit
spread that debris out
because of the not...
uniform nature of the gravitational field,
because they're in different orbits
different orbital periods, different energies,
and so they start to spread out and
this is just the depiction of what it's
going to look like in February of next year.
The Cosmos debris spreads out a little bit quicker
because it's in a
a lower inclination orbit
so the perturbations are greater
and the green debris is the Iridium satellite
and it takes just a little bit longer to spread out.
But what you see, basically, is a ball of twine
and so the debris is everywhere.
So it only remains concentrated
for a very short period of time.
Now how do we know what's up there?
Well as I said,
the U.S. Space Surveillance Network
tracks the large things.
We have a cooperative agreement with D.O.D.
they characterize the large debris...
Using Goldstone, we can see down
to about 2 to 3 millimeters.
Now we can't track them,
but we can detect them.
We can figure out how big they are,
we can figure out what inclination they're in,
we know what their altitude is
and that then allows us to prepare a
statistical assessment of what the population is
and by doing this every year
we get an idea of the trend,
how the population is evolving.
And then for things smaller than about a millimeter,
then we have to rely
on the examination of returned surfaces.
Whenever the shuttle comes back
we do an extensive survey
to see what kind of damage it has incurred
even though the shuttle
and the International Space Station fly at the
the very lowest parts of low-earth orbit
where the spacial density, where the debris is less.
I mean that's the pristine part of Space
where the Shuttle and the Station fly
It's much much worse at higher altitudes.
Here are some, uh, let me go back...
I also have superimposed here
you know, damage levels.
These things, collision velocities again
are on average about ten kilometers per second.
It can be a little bit more or a little bit less
so a lot of energy involved.
Small particles can inflict great damage.
We first figured out that we had a problem
on one of the early Shuttle missions
we came back and had a pit in the window.
And we analyzed that pit and found out
it got hit by a fleck of paint.
And you think about it, every space craft
and every launch vehicle upper stage
is typically painted for thermal reasons.
And you know what happens
to your house's paint after about ten years.
So there's a sea of paint particles up there.
Now fortunately, these are typically
you know, much less than a millimeter in size
and they don't pose a real serious threat
to virtually all vehicles.
The Shuttle, however, is very special.
We reuse the vehicle of course, and so
if there's an imperfection in the outer pane
of one of the [inaudible] windows
then we have to replace it before we fly again
because the launch stress is what might
propagate that imperfection.
But in general,
every spacecraft is vulnerable
particularly robotic spacecraft which is the
primary concern I think of most people in this room
are vulnerable to five millimeter particles.
We can only protect up to about
one centimeter size particles.
These are some cases of
impacts on the International Space Station.
Actually the upper-left is the
largest impact we've had on the Station.
Fortunately it hit on the area of a
Russian module that had substantial thermal blankets.
It penetrated the thermal blankets.
If it hit another part
it could have gone through a pressure wall.
But we have quite a bit of, um...
actual debris shields on the station
I'll show you about that in just a second.
This is one of the multi-purpose logistic modules
which fly to the Station only for about,
you know, ten days or up to two weeks,
during a Shuttle mission
and is brought back right away.
And during one of the flights,
one of the early flights actually,
we had a penetration.
But it's a double wall
so there was no problem in terms of the
safety of that particular module to the crew.
As I said we investigate the shuttle
after every flight.
This is one of those impacts on the window blown up.
This is a hole in the radiator.
You know the big, large, aluminum structures
inside the cargo bay doors.
Great witness plate for me
but it's a risk to the shuttle because
as you might imagine it's a radiator,
there are tubes underneath
those sheets of aluminum
and if you penetrate a tube
you have a substantial effect
on the thermal control capability of the vehicle.
Alright, NASA has pioneered
this whole area of orbital debris
and we started putting out specific
what originally were guidelines in 1995
they're now called requirements.
Actually today is the 30th anniversary of the
establishment of the NASA Orbital Debris Program Office.
Beginning of the fiscal year of 1980.
we have a system set up
as a relatively formal system
that every single project and program
with NASA that's going to fly in Space
has to prepare what's called
an Orbital Debris Assessment Report.
And it's first submitted at P.D.R.
and then again at C.D.R.
it actually now is a living document
you have to maintain it.
And then I had the privilege
of reviewing every single one of them
to gauge whether or not it's compliant
with the requirements that we have.
There are also special risk assessments
performed for the Shuttle before every mission.
There are certain requirements
maximum risk which we allow
in terms of loss of crew and vehicle
in terms of maybe having to
terminate the mission early because
the radiator got penetrated
and whenever there's a fragmentation event
because as you saw from the earlier illustration
debris goes all altitudes.
And so there could be
an explosion at 600 kilometers
that can affect the International Space Station
down at 350 kilometers.
And I've gotten many calls
at two and thee o'clock in the morning
saying, from D.O.D., saying
"We've just noticed an explosion."
and then we have to go back and
quickly, real-time do an assessment,
to make sure that that particular event
does not pose an undue risk to
human Space life or even some of our
more valuable robotic spacecraft.
And then finally, the ISS I said it
we have substantial dedicated shields on Station.
If you remember there was a chart
yesterday that said
at mission complete
the mass of the International Space Station
will be 400 metric tons
and a little bit more than that.
Five percent of that is dedicated shielding.
And you think about
how much it costs to put a kilogram in Space
look at the cost then that we've had to incur
just for orbital debris
to be able to maintain the International Space Station.
Alright, we've got very good top-level support.
There have been two inter-agency
U.S. Government inter-agency documents
on orbital debris:
a 1989 and then a 1995.
The President's national Space policy
has mentioned orbital debris mitigation
since President Reagan in 1988.
The current national Space policy
came out in August of 2006
and if you get these charts later on you can read this
or you can download it from our website.
This is verbatim what it says.
Basically it says that
you know, orbital debris poses a risk
to operations in Space
and it poses a risk to people in Space
and on the ground.
And I'll talk about the ground part
here in just a minute.
And then we developed,
as a result of the 1995
direction from the White House,
D.O.D and NASA were tasked to go out
and develop what we would call the
United States Government Orbital Debris Standard Practices.
These are the things you should be doing
and the design and operation
and disposal of your vehicles,
including spacecraft and launch vehicles.
And then the last part
which is also important, it says
"The United States shall take a
leadership role in international fora,"
and we have been doing that.
We created under the auspices of the
Office of Science and Technology Policy and the White House
a multi-year strategy for handling orbital debris.
We did this in the late nineties
and we just signed off,
completed every part of it, in 2007.
And it said
"First, get our own act together."
There were differences between NASA and D.O.D.
and the other agencies weren't even really
thinking about orbital debris.
So first we came up with these standard practices.
We then took those standard practices to the
what's called the
Inter-Agency Space Debris Coordination Committee
which is an organization of the eleven major
space-faring agencies of the world.
You have to be an agency to be a member.
NASA is the U.S. representative.
I'm the head of the NASA delegation to I.A.D.C.
but my delegation includes D.O.D.,
it includes State, it includes the [inaudible],
because they're all players in Space operations.
We went to the I.A.D.C., convinced them
and developed the first international guidelines
on orbital debris mitigation.
And then,
the last step was to go to the United Nations
and we did that and were very successful.
So what are the debris mitigation guidelines?
They're very general and straight forward.
You don't want to create debris unnecessarily.
In the past we actually had been doing that.
Like, in many cases you create
pollution sometimes without thinking
about the consequences.
Minimize debris generated by accidents.
The vast majority of debris,
which is a hazard to Space operations,
comes from accidents.
Then we will worry about safe flight profiles
and how you design your vehicle,
what altitudes you fly at,
and then what do you do with it at the end?
It turns out that is probably the most
crucial element of this whole problem.
And then in 2002 we were able to get the I.A.D.C.
to put together these guidelines.
I said there are 11 members of the I.A.D.C.
it's a consensus organization.
which means every single member
has to agree to these guidelines
before they can be developed, and that's quite a bit.
But if you really want a challenge,
work in the United Nations.
I've been the U.S. technical expert
at the U.N. for 13 years
and you're sitting in a room with 70 plus members
and it's a consensus organization
and every single country
sitting in the room has to agree with it
and the, all the major official languages of the U.N.
and every single word
is up for debate and negotiation.
But, all that being said
in 2007 the United Nations did approve
the Space Debris Mitigation Guidelines.
And they're now out to everybody in the world.
You can see them from the NASA website.
And they're almost verbatim
from what we had before but,
you know, some of the words are a little bit different.
Alright so, Green Engineering and Orbital Debris.
Green Engineering is really not a term
we use in my discipline.
In fact, my first...
connection with Green Engineering was 40 years ago
when I was an avionics technician in the Air Force
and we had a motto there that, you know,
if it moved, you safety-wired it
so it wouldn't come out during flight
and if it didn't move
you painted it green so it wouldn't rust.
And so when I was on the flight line
I had a can of spray green paint to paint things
but this is sort of a different connotation now.
Initially, of course, in the sixties, you know,
we were just happy to get into orbit, you know.
That was the challenge.
So we would throw things off intentionally.
Springs, we have explosive bolts
we didn't care where the pieces
of explosive bolts went,
we had covers for sensors,
particularly cameras and [inaudible] control sensors
we'd just throw them away
and we didn't think too much of it
and gradually as you saw from the early graph
that slowly accumulates in terms of
number of objects still in orbit.
So now most missions are
debris free by design.
It's taken a long time to convince
the aerospace engineers
developing launch vehicle spacecraft
that this really is
in their own best interest
so that we can maintain space operations.
The term that is come into vogue
even in my area is
"sustainability of space operations."
It was actually a term
coined by the Chairman of the
Technical and Scientific Subcommittee
of [inaudible] in the U.N.
Gerard Boucher from France
when he was the chairman.
And it's the theme of the
International Astronautical Congress which
convenes about ten days from now in South Korea
This is very important to the
international aerospace community.
If we see...
events which produce debris
then we now tackle them immediately.
The Delta IV launch vehicle
is relatively new.
The Japanese developed
the H-2A several years ago.
When they first started to fly,
they were producing debris
which was not expected.
And so in both cases the U.S. and Japan
immediately tackled that and said
"What's going on? We need to stop this."
And the Japanese have been successful
and the U.S. is still working on Delta IV
but I think it's getting better.
Spacecraft and orbital stages
have to be passivated at
the end of the mission.
Passivation simply means
get rid of all the stored energy.
You know, we don't always know why
a spacecraft or a launch vehicle blows up
but there have been over
200 fragmentations reported since 1961,
the vast majority
were accidental explosions
over 140 from vehicles
which had successfully completed their missions.
They were spacecraft or they were launch vehicles
that did exactly what you asked them to do
and then you left them on their own
when you turned them off
and then spontaneously, a day later,
sometimes 25 years later, they blew up
into hundreds of large pieces
and many many more smaller pieces.
The reasons of course are varied
depending upon the design.
It's not always propellants
it could be pressurants, it could be batteries,
but, we finally decided, you know,
let's just get rid of all the energy
and this can't happen.
And we basically have been
100 percent successful.
Once you passivate a vehicle it just doesn't
have the possibility of blowing up.
And this has been one of the
great success stories, actually.
And when we go to designers
of launch vehicles and spacecraft
they say, "Well oh yeah that makes sense."
And in almost all cases it's very very easy
to fix the problem.
You vent the pressurant,
you turn the engine back on
and burn off all the propellants
or you vent the propellants,
it's really not that big of a deal.
And so we get actually very good compliance
on the launch vehicle side.
A little bit more of a challenge
on the spacecraft side.
Classic, you know, cultural phenomenon:
"We've been building spacecraft
"like this for decades,
you know, why should I change?"
Well, you know,
we have seat belts in cars now,
we have catalytic converters
which we never used to have
but there's a reason for them,
and eventually, we're getting there, you know?
One of the things when we first
started out we said look:
"You don't have to go back and
"retrofit series spacecraft.
"But if you have a de novo design
"here's your chance, you know
"start with a clean sheet of paper,
let's do it right,"
and we're making good progress.
Reduce the potential
for future accidental collisions
because they create debris.
So one of the ways to do it is
to get rid of these guys.
And so NASA came up with a metric
a criteria that says
when you're done with your launch vehicle
or your spacecraft in low-earth orbit
make sure that somehow
it's gone within 25 years.
Typically what you do, you know if you're
below 600 kilometers it'll happen naturally.
Mother nature will take care of you.
If you're above 600 kilometers
you need to probably bring your vehicle
back down to a lower altitude.
And then withing 25 years
mother nature, again, will take care of it.
This was a good thing...
and it does prevent the growth
of a lot of mass in orbit.
Because mass is the metric
that we're concerned about
because where there's mass,
because of collisions
there will be more debris.
The less mass,
the less future debris.
In geosynchronous orbit
obviously you can't come down
out of the environment
so you just want to get away from that
very valuable and unique resource
the [inaudible] orbit.
So we say, "Just go up like
200 kilometers and stay away."
You do have to worry about perturbations.
Make sure you don't automatically
wind up coming back after some period of time.
And it only takes like 10 kilograms
of propellant to do that at that altitude.
So this is not a real serious problem and
Spacecraft operators [inaudible] have been doing this
now since the seventies.
We have relatively good compliance internationally.
Not complete but, you know, we're
working on doing a better job.
[Inaudible] though we're encouraging operators
to get rid of their vehicles in 25 years.
Well, where are they going?
They're coming back to earth.
So what we're doing is
we're taking an on orbit risk
and we're transferring it
into an on the ground risk
because particularly, if you have a vehicle
that weighs more than a few hundred kilograms
almost always they'll be components
of those vehicles which survive reentry.
You know, this notion that everything
burns up on reentry, just is not true.
Practically any spacecraft or launch vehicle
will have components.
Some many components,
some very large components.
You saw a picture yesterday of a big tank
that came down in Georgetown, TX
just north of Austin
with a woman bending over it.
Well I took that picture [audience laughter].
That was a T.V. reporter.
What you didn't see,
because of the angle that I selected,
all you saw was a farmhouse in the far distance.
Well if I turned about 90 degrees
and took the picture,
you'd see a farmhouse was
about 100 meters away.
And this farmer's wife
went to bed that night
there was nothing in their front yard
and during the middle of the night
this thing comes crashing down.
So there is a risk
and we recognize that risk
and the bottom line here in the end is that
we have adopted in the U.S.
and is gradually taking international acceptance
a criterion that says:
"The reentry risk from any object
should be no greater than 1 in 10,000."
If it is, then you probably need
to do a controlled de-orbit.
Mentioned yesterday, logistical vehicles,
International Space Station are typically
dropped into the Pacific.
In fact, there was a
progress spacecraft just earlier this week
that was dropped into the Pacific Ocean.
When the time comes
the entire International Space Station
will be dropped into the Pacific Ocean.
Hopefully, you know, after 2020 and
however long we can maintain it.
But we, before we started bending metal
on the International Space Station
we were thinking about:
"Oh my God, how do we get rid of it?"
It's 400 metric tons.
You can't let that thing come back by itself.
You know you have to put it in the ocean
Just like the Russians did with Mir
and the previous space station.
How do you move 400 metric tons
and put it right where you want it?
Well this is a work in progress [audience laughter]
we don't really have all the answers
but we kind of know
how we might get away with it.
As you remember in May,
the Shuttle went up to
supposedly the last servicing mission
for the Hubble Space Telescope
and people would say
"Well that's the last time we're ever
going to visit the Hubble Space Telescope."
Not true.
NASA is committed to
doing a controlled de-orbit of Hubble
because it weighs so much, it has so much mass,
that its risk to people on the ground
is too great that we can't let it
come in uncontrolled anywhere in the world.
So, at some point,
probably in the end of the next decade,
we will go back and visit HST
either robotically, or with CEV or with something,
attach a de-orbit motor,
and drop it into the Pacific.
We, because of this...
we at NASA,and particularly at Goddard,
give them credit,
have a program called
"Design to Demise."
And it kind of...what it says.
What you like to do is
build your spacecraft out of materials
which don't survive re-entry.
Which means you don't want to use
high melting temperature materials
like titanium, beryllium, stainless steel,
materials that actually
we've been using in spacecraft
and launch vehicles for many many years.
And we chose them for convenience
and sometimes we chose them because
they had specific material properties
which we felt were essential,
particularly in the payloads.
Payloads sometimes are the hardest ones to retrofit
because...the unique properties,
you need coefficient of expansion and everything,
that you have to worry about.
But what we're trying to do is replace
those high melting temperature materials
with lower melting temperature materials
like aluminum.
I'm sure you remember
in January and February of last year,
the United States Department of Defense
had a spacecraft called U.S.A 193
which had malfunctioned
contained hundred of kilograms of hydrazine
and was about to reenter
in an uncontrolled manner
because they had lost control right after launch.
The problem we had was that
all that hydrazine was in a
very large titanium tank,
and titanium tanks typically
reenter very very well and in one piece [audience laughter]
We actually in my office,
we do reentry analysis for every NASA vehicle
but we always look at them
as if they were empty because
the earlier guideline says
you've got to passivate the vehicle so
you've already gotten rid of all the propellants.
We had actually never worried about
a failure scenario
in which we had a full hydrazine tank
and D.O.D. hadn't either.
And so I was the NASA representative
on an inter-agency group
that the President charged with
trying to neutralize this threat.
and as you well know
we were able to negate that threat
by blowing the thing up just before it reentered.
But that's not an action
that we normally want to take.
And as it turns out,
not very well known,
certainly not to the public,
a few months after that activity
to negate that particular threat
NASA launched the GLAST satelite
that contained several hundred
kilograms of hydrazine
in a titanium tank.
And if GLAST had or,
actually, if it were to fail today,
we would have a very similar problem.
We would have tank with frozen hydrazine
which would be eventually coming back to Earth
because it's at a relatively low altitude.
So we're now looking at ways to prevent that
and Goddard has already done this.
They've now designed a tank
for hydrazine which is not titanium.
And it will demise.
So the trick here is
to come up with better materials.
In this case better is lower melting temperature.
But it's a, again, culture change
for the aerospace industry
and you really have to work very hard
to convince them that this
is something that really is necessary.
It costs a little bit to design this
but now that you designed it,
you know, that cost is gone
and it's just as easy to build an aluminum tank
than it is a titanium tank.
Alright, what's the long term?
We have known for actually 30 years plus,
that the real long-term problems are
objects running into each other
just like we saw on February.
We knew that was going to happen.
Can't tell you when it was going to happen,
I'm not Gene Dickson, I can't foresee the future.
But, we knew that was--
I mean statistically it's inevitable.
And so a colleague and I had an article in Science
in January of 2006, that basically
we're just taking a new look at the problem.
We said: Beginning of 2006
nobody in the world ever launches
another object into Space.
All we have is what's up there.
What's going to happen to...debris population?
Well, you initially have decay of fragments,
decay of intact objects
but, you know, low-hanging fruit,
you know, it's exponential in terms of
longevity once you go to higher altitudes
so after you get rid of the
low altitude stuff below 600 kilometers
everything else is up there for many many decades
and hundreds of thousands of years
and so what happens is
you start having these random collisions
and within about 40 or 50 years
you actually start having
a net increase in population just because
you're creating debris quicker than it's
falling out of the environment.
Well, that was optimistic for many reasons
one is:
we assumed nobody was doing any launches,
nobody was doing anti-satellite tests,
there were no more accidents going on.
So here's a chart we put together
just actually a few weeks ago.
Brand new, off the press.
Hasn't been shown by--seen by anybody.
The biggest problem is
when we did the earlier study
we were down here
but already we have the problem that
we have a lot more debris up there
than we did three years ago
because of the Chinese test and the accident
in February of this year.
And then we go through a bunch of scenarios
that say "What if you did absolutely nothing at all?"
And of course that's the worse case
and that's the top line.
And then what if you kind of
ignore what you're doing today
but you make a commitment to start
pulling big things out of orbit?
How will that affect the environment?
And that's what these three curves are right here.
And then what we really want to do
is continue to be compliant
with the guidelines that are out there today,
both nationally and internationally.
And in addition to that,
that alone won't prevent
the growth of the Space debris environment.
So we have to start thinking about actively
removing large objects from earth orbit.
That is the long-term problem.
Now we do have an advantage that,
you know, the climate-
change community doesn't have.
You know there's a perception,
perhaps reality,
that climate change is something
which is coming very quickly in a relative sense.
This problem is much much longer.
I mean it's still exponential
like so many things are in nature
but it's got a long time constant.
This is a hundred year scenario.
And the worst case scenario if I did nothing;
worse case, you know, what
the environment doubles in a hundred years.
Well, this is not
what you typically read in the paper
or the science fiction magazines
where all of a sudden
you can no longer use earth orbit,
you can't fly a weather satellite
or a navigation satellite
or a human piloted satellite
because it's too dangerous.
That would happen...
but we're not talking eons down the road.
So we do have time to do this.
We don't have to worry about doing it
over the next five or ten or even fifteen years.
Now finally, I do have what I think
are some worthwhile lessons learned
and perhaps have application
in your individual areas
where you're more concerned about
terrestrial pollution.
Again, obviously in the long term we
we have to worry about
Green engineering in Space.
The United States and the international community
have already been very proactive.
This is one of those
relatively rare areas of pollution
where we recognized the issue
before it was a problem.
We knew this was going to eventually happen
and we're tackling it early. So...
actually the last 20 years
when we're going out and preaching the gospel
of Space debris mitigation,
we have not worried so much
about the longer term
we're trying to educate people
saying "There are some simple things
"you can do right now
"which will have a dramatic impact,
a positive impact on the future environment"
and that's what we've been pushing.
How we did that
and why we were successful
is NASA put in a lot of resources,
and Louis can attest to this,
to make sure we understood the problem.
And then we took that message out
to the technical community because
those are the people that have to respond to it.
And then we also had to develop
effective and acceptable policies and guidelines.
You know, if I say, you know,
you can't ever use titanium
again in a spacecraft, well,
you know, you just sort of turn me off.
You know, so we work with
the aerospace engineers
to find solutions.
You know, if I tell you you have to de-orbit
from geosynchronous orbit, you know,
that's a non-starter as well.
So you have to find things that work and
at least we've been fortunate in our community
there are some very helpful activities
and design processes that will do that.
The other thing we did
we also worked very closely with the
international community. This is not a...
U.S. only problem, you know?
We can't fix it
and we're not responsible for all of it.
Now, you know, we have our share of
responsibility in terms of debris up there
but the Russians and the Chinese
are about equal with us right now.
But it's an international issue
so what we want to do is make sure
that when we put in place these guidelines
they are accepted internationally
so that our industry is not
put at an economic disadvantage.
And so ESA certainly has been on board with this
from the very early days.
In fact, the very first organization
that NASA went to to discuss this
on a bilateral level was with ESA
and got a very very good reaction.
The long term remediation of the environment
is really what we need to do.
And that's a term that we
actually have not been using much
until the last several years.
Again, we don't think it's urgent
but clearly since the February event
a lot of people are talking about remediation.
The problem is...
we don't know how to do it.
It's either technically impossible,
depending upon your concept, your technique,
or we can't afford it.
And so you have to find something that will
meet both of those criteria
and I've been thinking about this
for a long, long, time
and still haven't found anything.
And since February
we've been getting a lot of unsolicited suggestions
of how to clean up the environment
and in December DARPA and NASA
are cosponsoring an international conference
in the Washington area
on orbital debris removal.
If we knew how to do it
we wouldn't have a conference
we wouldn't ask people to come in
and give us good ideas.
I've seen a lot of good ideas
from some smart people and
some lay public people.
But we're still struggling.
We can't find anything which is good
either for the small debris environment
or for the large debris environment.
but, you know, as time goes on
as technology improves,
if the economics of Space transportation
ever come down and improve,
you know some of these things may now
look a little bit more attractive
than they do before.
So if there are any other questions left,
we're back on schedule.
[audience applause]