[meteorite-list] Protecting the Planet: SPACE.com Q&A with Asteroid Hunter David Morrison

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:00:04 2004
Message-ID: <200207021610.JAA14231_at_zagami.jpl.nasa.gov>

http://www.space.com/scienceastronomy/astronomy/morrison_interview_020702-1.html

Protecting the Planet: SPACE.com Q&A with Asteroid Hunter David Morrison
By Robert Roy Britt
space.com
02 July 2002

David Morrison figures his long effort to keep the world safe
from asteroids has been very successful. "In 11 years of protecting the
planet, not a single human has been killed," he pointed out to me recently.

-----------------------------------------------
           THE ODDS
 Odds are you'll die somehow.
 For U.S. residents, here are
 some ways, and some odds the
 experts have applied to
 them:

 Car Crash: 1-in-100

 Electrocution: 1-in-5,000

 Asteroid Impact: 1-in-20,000

 Plane Crash: 1-in-20,000

 Tornado: 1-in-60,000

 Bite or Sting: 1-in-100,000

 SOURCE: Chapman & Morrison,
 Nature, 1994
-----------------------------------------------

Morrison is of course not the only person working to save Earth from
potentially deadly space rocks. But the sometimes outspoken, always affable
space scientist at NASA's Ames Research Center was one of the first people
involved.

In the early 1990s, he chaired a committee that generated the Spaceguard
Survey Report, which advised NASA and Congress to search for and determine
the paths of all Near Earth Objects (NEOs), asteroids and comets larger than
1 kilometer (0.62 miles) that roam the region of space also occupied by
Earth.

Morrison is a moderating voice in a field whose most vocal members are
sometimes accused of attempting to frighten the public. That doesn't mean he
thinks we're entirely safe.

"The impact hazard is real, and it is of a magnitude at least as great as
many other natural hazards," Morrison testified before Congress in 1993.
"Over long time spans, impact catastrophes are inevitable. What happened to
the dinosaurs can happen to us."

What happened to the dinosaurs, and many other species of their time, was
that they were annihilated by the global effects of an impact by an asteroid
the size of a city. Sixty-five million years later, the Spaceguard
recommendations were adopted, and today a worldwide effort funded partly by
NASA and involving several institutions has found about half of the roughly
1,000 large NEOs thought to exist.

Today, Morrison chairs the working group on NEOs in the International
Astronomical Union, a volunteer position. He also maintains a comprehensive
Web page on the subject.

He typifies the pieced-together nature of the overall effort to guard the
planet, one dominated by part-time contributors, arguably underfunded
programs and a league of amateurs who do much of the grunt work -- follow-up
observations that help determine if a recently discovered NEO is on course
to one day hit Earth.

At a recent gathering of astrobiologists, where Morrison wore the hat he
gets paid for as Senior Scientist at the NASA Astrobiology Institute, he
told me he views his asteroid watch as a hobby. I sat down with the Harvard
Ph.D. to discuss the often controversial state of his part-time industry,
the search for NEOs and the question of what to do if we find one with our
name on it.

-------------------------------------------------------------------------

SPACE.com: Why are asteroid impacts a hobby for you?

David Morrison: Several of us who have been interested for 10 years or so in
the question of whether Earth is at hazard from asteroids and what's the
right way to handle this issue have, for the most part, not received any
direct funding from NASA to do it. It is not our primary job.

But I think it's fascinating science and an important policy issue, so I put
some time into it.

SPACE.com: In the search for potentially threatening asteroids, what are we
doing right?

DM: We are efficiently finding the NEOs 1 kilometer [0.62 miles] or larger
in size, which is a range that includes anything that is a global threat;
that is, that could produce a global environmental catastrophe. We're more
than halfway there. In fact, we have reduced the risk from an unexpected
asteroid strike by about a factor of two.

We reduced this risk without actually having to move anything.

We do not expect any of the remaining [undiscovered] objects to be on a
collision course with Earth. It would be bad luck if they were. On the other
hand, if one is on a collision course, we want to know it. I think probably
by 2008, when we have 90 percent of the larger NEOs catalogued, we will have
concluded that none of them is a risk.

But the possibility that we're unlucky, that an impact might create a truly
global catastrophe and kill hundreds of millions of people, motivates us to
carry out the search and be concerned about this issue even though it's a
low probability risk.

We deal with such things in ordinary life. For instance, when you buy fire
insurance on your house, you actually don't expect your house to burn down.
Most people go through their entire lives without having a major fire in
their house. But you still buy the insurance.

SPACE.com: We always hear that eventually, Earth will be hit again,
statistically speaking. When?

DM: A large impact is not something we expect to happen in our lifetime, in
our childrens' lifetime, or even our grandchildrens' lifetime. It would be
very bad luck if it did happen. But it could happen at any time.

Ultimately, the reason we can deal with this scientifically is that it's not
a statistical random chance. Somebody doesn't throw the die every year and
decide if we're going to be hit that year. If there's an object out there
that's going to hit us, say, in the next thousand years, it is already on a
collision course. So it can be found, its course can be determined.
Asteroids don't change orbits capriciously, as is often depicted by
Hollywood.

SPACE.com: Scientists and journalist constantly spout statistics about the
asteroid threat. But in some sense the statistics are meaningless and may
fuel some apathy among the general public.

DM: That's right. The issue is not one of refining the statistics. It's not
whether it's a 1-in-a-million or a 1-in-2-million chance that it will happen
this year. It's an absolute thing. Will it or won't it happen?

SPACE.com: What are we doing wrong in the NEO search?

DM: We have not yet seriously considered what the next step should be. In
2008, when we have found 90 percent of these larger NEOs, do we just keep
going to get 95 percent or 99 percent? [The final few will be the toughest
to track down, experts say.] Do we try to segue into larger telescopes so we
can find fainter [and thus smaller] objects, those a few hundred meters in
size that could produce a tsunami and wipe out the coast around an ocean
basin?

We have been so focused on the immediate, higher-priority problem that there
hasn't been much thought given yet to the next level.

One group that has considered the next level is in the United Kingdom. The
UK NEO Task Force recommended two years ago that we set another goal, that
we raise the bar and focus on [smaller and thus dimmer] 300-meter [roughly
equal to three football fields] objects, which requires a new generation of
search telescopes.

In the United States, we haven't done anything either to build such
telescopes or even to plan for it.

SPACE.com: Is this just because the plate is full?

DM: It's partly because the plate is full. It depends on whether you think
of the asteroid search funds as a fixed sum of money. If we are level-funded
at $3.5 million a year, which is what NASA is now investing, then that
pretty well all goes to the current search.

On the other hand, the National Research Council has recommended that the
U.S. build a Large-aperture Synoptic Survey Telescope (LSST), a new
instrument that could in fact do the survey down to 300 meters, by itself,
as well as a lot of other good astronomy. Astronomers at the National
Science Foundation are looking at that.

SPACE.com: If I promised you a billion dollars a year, where would you put
it?

DM: I would not know how to spend a billion dollars a year on asteroids.

SPACE.com: But we keep hearing that it will be very expensive to find
smaller asteroids.

DM: The smaller you go, the more expensive it is. This LSST has been
estimated at about $180 million to build plus roughly $20 million per year
to operate. So if you found that kind of money you could build such a
telescope.

SPACE.com: So if I gave you a billion, you wouldn't put it all into NEO
research?

DM: That's right. I wouldn't. Because I don't think it could be justified.

But there is another perspective that has to be seriously thought about. We
always say that if we found an NEO on a collision course, we have the
technology -- in principle -- to deflect it. But of course we've never
actually done it. We've never done any experiments.

The alternate perspective says we should develop and test such deflection
technology, that we should take an innocent asteroid that's not on a
collision course and try sending a spacecraft to deflect it.

SPACE.com: A billion might come in handy for that.

DM: Yeah, it would [laughs].

The space program doesn't normally operate this way, but you could set out a
challenge, some sort of international prize for the first group that changes
the velocity of an asteroid by 2 centimeters per second [0.04 mph]. They
could do it with an explosion, nuclear or non-nuclear, by putting a solar
sail on it, or whatever.

[A minor velocity change would induce a change in trajectory as an asteroid
interacted gravitationally with the Sun, planets and other objects, putting
it on an entirely new course.]

SPACE.com: Some vocal members of the NEO community are going to read this
and say, "Here's the NASA voice again saying we're on track, we just have to
worry about the big ones. But it's the small sucker punches we need to worry
about, and we need to worry about them now." What do you say to those
people?

DM: I'm not sure what point they're trying to make, because they speak as
though with a small one we're likely to have less warning. I don't
understand that argument.

Right now we catch any 1-kilometer or larger object that comes within a big
volume of space -- within about 100 million kilometers [62 million miles] of
Earth. To carry out a complete survey of 300-kilometer objects, you need to
look at the same volume of space but detect fainter objects. The survey
procedures and warning times are about the same.

SPACE.com: But it's easier for a small asteroid to escape detection, and
there are more of them. So the chances are greater we'll get surprised by
one, at least until they have been catalogued.

DM: That's right. But in that case you'll really be surprised. The first
you'll know of it is when you see the sky light up as it enters the
atmosphere.

If we haven't started building new telescopes within the next year or two,
they won't be ready to take over in 2008. So now is the time to go on to the
next step. But I think the search philosophy remains the same. Whether it's
big ones or little ones, you carry out a survey, make a catalogue, calculate
orbits, and predict future encounters with the Earth.

We can predict the impact of a 100-meter or 50-meter object just as far in
advance as a kilometer object, once we find it.

SPACE.com: Aside from this conversation, you're wearing your astrobiology
hat today. In your mind, is there any connection between asteroids and
astrobiology?

DM: Yes, certainly. Astrobiology is more than just a search for life.
Astrobiology is an effort to understand life as a planetary or astronomical
phenomenon. We look at the long-term interaction of life, the environment,
and the planet.

In that context, asteroid impacts are very important. We don't know how
important, but it's at least possible that on Earth, impacts have been a
major driver in evolution, because by producing mass extinctions, you
essentially open up a huge number of ecological niches. After a mass
extinction the rate of speciation is huge, a very quick radiation of new
species. Impacts and their environmental effects, both past and future, are
one of the elements of astrobiology.

To me, realizing that the end-Cretaceous extinction [dinosaurs, et al.] is
due to an impact is illustrative of how fragile the biosphere is. That's a
tiny impact compared to the planet as a whole. It's not enough to change
orbit, or rotation, or magnetic fields or anything, yet it produced an
ecological catastrophe, redirecting the course of biological evolution on
our planet.

It is trite but true: Without the end-Cretaceous impact, humans would not be
here.
Received on Tue 02 Jul 2002 12:10:21 PM PDT