is a real priority for national security,"
astronaut and alumna Sally Ride told a packed
audience April 10 during the annual Drell Lecture,
sponsored by the Center for International Security
and Cooperation (CISAC). Space has been used for
military purposes for decades, she said, although so
far no weapons have been deployed in space and no
ground weapons have attacked satellites.

That may
change if the Bush administration succeeds in its
hotly debated plan to develop space-based missile
defense systems. As the Drell Lecture promotes
examination of issues in international policy, Ride
took the opportunity to explore technical issues that
might arise if weapons were put into orbit.

policy questions going forward might be sort of
simplistically stated as: Does it make sense for us
to put weapons into space? Does it make sense to
develop anti-satellite weapons, or A-SATs?"

would be "disastrous," she said, because
the space debris they would create could damage the
many satellites traveling in low-Earth orbit ­ 150
to 400 miles above the Earth. "It’s a very, very
typical orbit," Ride said. It is where the space
shuttle, the space station, photoreconnaissance
satellites and some navigation satellites circle.
"Anything in low-Earth orbit is traveling
really, really, really fast," she said.
"The space shuttle travels 17,500 miles per
hour, and anything in that same orbit has to, Newton
says, travel at that same speed."

asked: "What if anti-satellite testing proceeds
and we start testing rockets that clobber satellites
and explode them in space? What if enough of that
goes on that there’s the equivalent to a test range
up in low-Earth orbit?" Each explosion would
create billions of pieces of space debris orbiting at
5 miles per second just waiting to run into a

recalled a run-in with space debris on her first
shuttle flight. "About halfway through the
flight there was a small pit in the window of the
space shuttle and we didn’t know what it was. An
awful lot of analysis was done while we were in orbit
to make sure that the strength of the window would
sustain reentry. It did. We were all fine. But the
analysis afterward showed that our window had been
hit by an orbiting fleck of paint, and the relative
velocities were enough that the paint actually made a
small but visible gouge in the window. Well, a fleck
of paint is not the same as a small piece of metal
traveling at that same speed. So, as soon as you
start increasing the amount of junk in a low-Earth
orbit, you have an unintended byproduct that starts
putting some of your own quite valuable satellites at
possible risk."

satellites provide communication, reconnaissance,
navigation and monitoring. Intelligence agencies and
the military currently use about 100 satellites as
part of our national security, Ride said. They
capture images during the day in visible light, at
night in infrared light or through clouds using
radar. They monitor global hotspots, pinpoint missile
launch points for early warning, communicate enemy
activity and allied actions. A satellite that in
peacetime uses a global positioning system for
navigation may in wartime target bombs or remotely
piloted vehicles.

current landscape is that the United States has an
absolutely huge advantage over every other country in
space capabilities," Ride said. "It’s hard
getting to space. It’s hard developing things that
work in space, and it’s really, really hard to get
things to work reliably over long periods of time in

On the
25 other hand, many countries have sophisticated rockets
that can launch objects into space. Many operate
satellites. And China expects to launch a person into
space within the next year.

attended Stanford, where she received bachelor’s
degrees in physics and in English in 1973, and
master’s and doctoral degrees in physics in 1975 and
1978, respectively. She flew aboard the space shuttle
Challenger in 1983 and 1984, and served on the
presidential commission investigating its subsequent
explosion in 1986. During the lecture, she gave a
quick overview of the space race, shared her space
photos and addressed the capabilities and limitations
of satellites and other space assets used for
national security.

photos unflinchingly looked down the eye of a typhoon
in the Indian Ocean, chronicled massive erosion in
Madagascar and showed dramatic differences in water
reclamation at the Egyptian-Israeli border. But one
photo, of the Earth’s horizon, was striking because
it revealed stakes that transcend the security of any
one nation.

you take a look at where the blackness of space ends
and Earth begins," Ride pointed out,
"you’ll see a very, very, very thin royal blue
line. That thin royal blue line is Earth’s
atmosphere. That’s all there is of it. That’s all
that separates everything we know on our planet from
the vacuum of space. And it’s a very, very striking
sight to every astronaut the first time he or she
looks off toward the horizon because it just drives
home that we live on a planet, and our planet is very

Drell Lecture is named for physicist and arms control
expert Sidney Drell, with whom Ride worked as a CISAC
Science Fellow when she left NASA in the late 1980s
to reenter academia.

currently is a physics professor at the University of
California-San Diego, director of the University of
California’s Space Institute, and president and chief
executive officer of Imaginary Lines, a company she
founded to support girls’ natural interests in
science and technology.


thin blue line during the Cold War

the thin blue line is where the military has cast its
eyes ever since 1957, when the Soviets launched the
Space Age with the first satellite, Sputnik, a
celestial basketball containing little more than a
radio transmitter. It beeped incessantly as it
circled the Earth every 100 minutes or so ­ a
constant reminder to Cold War America that the
archenemy it considered technologically inferior was

had a huge psychological impact on the United States,
Ride said. "It had enormous consequences for the
course of the country and also for the course of our
national security."

was launched by a powerful and sophisticated rocket,
and once a country developed such a rocket, it had
the makings of an intercontinental ballistic missile.
"When you lift something with a rocket and push
it into orbit, all you need to do is give it a little
bit lower push. Instead of going into orbit, it’ll
land on your adversary half the world away. That fact
was not lost on anyone in the United States."

to their vulnerability, Americans responded with an
urgent call for science education reform, the
creation of NASA and new space-oriented military

became the measure of a superpower, Ride said, and
the Russians continued to pull off a few consecutive
firsts: Sputnik II quickly followed the first Sputnik
with the launch of a dog. Meanwhile, Americans
suffered "a series of reasonably spectacular and
very public failures," Ride said. Before a
television audience, rockets blew up sensationally on
the launch pad.

first U.S. satellite finally went into orbit in 1958;
it discovered Earth’s radiation belts. But that
achievement was quickly eclipsed when Soviets
launched the first person, Yuri Gagarin, into space
on April 12, 1961. When Americans launched Alan
Shepard into space a month later, the Soviets were
quick to point out that Shepard’s journey was only a
suborbital flight, as the rocket that launched him
wasn’t powerful enough to put him into orbit.

Kennedy responded by announcing a bold plan for
leapfrogging the Soviet Union: America was going to
send a man to the moon and return him safely before
the decade was out. He made that announcement before
America had ever put a single person into orbit.

was really a point in time where space was taking
center stage," Ride said. "You definitely
had the national security and military overtones
around the whole experience."

In the
early 1960s, reconnaissance satellites reassured
America that a "missile gap" did not exist
between it and the Soviet Union. Surveillance
satellites looked for signs of nuclear explosions, as
atmospheric testing had caused communications
blackouts that lasted for hours and paralyzed
satellites. Anti-ballistic missile defenses were
proposed to use nuclear-tipped rockets to intercept
incoming missiles in outer space. Programs were
established for military pilots ("space
bombers"), military astronauts and a military
space station. "The astronauts were
selected," Ride said. "They were trained
for a few years. There was actually hardware built,
but of course it was never launched."

blue line probably appeared thinner than ever, but
thankfully the rule of law prevailed. In 1963,
international treaty banned nuclear testing in the
atmosphere and in space, and in 1967 outlawed weapons
of mass destruction in space. Military bases on the
moon were banned. Other treaties prohibited
interfering with "national technical means"
­ spy satellites that were considered stabilizing by
both sides.