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HEALTH & SCIENCE
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Monday* July 18, 1994
Monday
Comet batters Jupiter
Target:
Jupiter
Diameter: 88,730 miles
Rotation: 9 hours 51 minutes
Gravity: 2.69 times that of Earth
Huge
chunks of ice, rock from SL9
begin seven-day planet barrage
Morning terminator
Surface rotates into sunlight
M '
'
f>*t* \ > \
GREENBELT, Md. (AP) — In a once-in-a-millenium
spectacular, comet Shoemaker-Levy 9 is pummeling
Jupiter with mountain-sized chunks of ice and rock,
sending up towering fireballs and leaving black scars
in the planetary clouds that may last for months.
Fragments A, B, C and D of the 21-piece comet
slammed into Jupiter Saturday and Sunday, repeated
ly exploding into fireballs that extend for 600 miles
above the cloud tops.
The impacts are all behind Jupiter as viewed from
Earth, but the bubbles of hot gases arising from each
hit poke over the horizon and can be detected by large
telescopes on Earth and by the Hubble Space Telescope.
“The fireball extends beyond the limb (visible hori
zon) of the planet,” Heidi Hammel of the Space Tele
scope Science Institute said Sunday.
She was speaking of a Hubble image taken of frag
ment A’s explosion. “This is a massive thing,” she said.
Fragment C, about the same 0.6 mile diameter as A,
smashed Jupiter about 4:45 a.m. EDT, and infrared
photos from the Keck Telescope in Hawaii showed two
glowing scars, each about the diameter of the Earth.
Fragment B is thought to have been much smaller
and less compact. No images were released of that
impact.
Fragment D views are not expected to be ready until
Monday. But more are coming.
“This is just the orchestra warming up,” said David
Levy, an amateur astronomer and a co-discoverer of
the comet.
Ahead are the largest four of the comet’s train of
21 pieces.
Fragments G and H, which astronomers predict
will hit on Monday, are both thought to be almost 2
miles across.
Fragments K, expected to collide Tuesday, and Ql,
which hits on Wednesday, are also about 2 miles in di
ameter. The last fragment, called W, is forecast to hit
on Friday.
Names of the fragments don’t neatly follow the al
phabet. Some fragments have disappeared, along
i
1
with their letter designation. Q split
apart, giving rise to two pieces with
that letter.
Scientists estimated that frag
ment A released energy equiva
lent to 10 million megatons of
TNT when it slammed Jupiter
at more than 130,000 miles
per hour. Since the energy re
lease increases geometrically,
the larger fragments could
have an explosive force of 10
times more.
Fragment A left a black
scar in the Jupiter cloud tops
that some scientists said
could last months, or perhaps
as long as a year, despite the
extreme currents that stir the
planet’s stratosphere.
The explosive force of the
comets comes from their size and
their extreme velocity.
Eugene Shoemaker, U.S. Geo
logical Survey astronomer and a co
discoverer of the comet, along with
his wife, Carolyn, and Levy, said tem
peratures at the collision can reach tens
of thousands of degrees.
Jupiter is almost all hydrogen gas, with
only a relatively small central core. But as a
high-speed comet fragment strikes, it creates
powerful shock waves in the upper atmosphere
and probably punches through a layer of am
monia clouds to a layer of dense hydrogen
miles below.
The shock waves create instant and extreme
heat. Powerful forces of deceleration crush the
comet fragments.
“Huge clouds rumble up and create a plume,”
said Levy. “That’s what we call a fireball.”
■ ^ »•
Moons
Jupiter’s 16
known
satellites orbit
the planet’s
equator, and
will not be hit
by any of the
21 major
comet
fragments.
c
0
Left to right:
Ganymede,
Callisto, to
and Europa
Limit of visibility
Left of line is not visible from Earth i
/L
Impact zone
All fragments strike on
the night side of
Jupiter, out of sight of
Shoemaker-Levy 9
Looking for ringside seats
View from Earth Jupiter
Impacts are hidden
behind planet.
Astronomers will look
anyway, to see if
anything can be
seen when impact
point rotates into
view a few minutes
later.
Hubble Space Telescope
Earth. Impact areas
rotate into view about
8 to 18 minutes later.
Site rotates into
sunlight 18 minutes
after that.
Earth
to scale
Great
Red
Spot
Giant
storm is
about
16,000
miles
across.
AP illustration by Karl Tate
The comet was drawn into orbit around
Jupiter at some time in the past (probably
around 1970-72). It was shattered into 21
pieces by Jupiter’s gravity in 1992. The train
of fragments, currently more than 2.5 million
miles long, is on course for smashing into the
planet between July 16 and 22.
Path of fragments
View from Galileo
Gets the best view of the impacts
Jupiter appears about 60 pixels
across in Galileo’s camera.
Since the probe’s
main antenna is not
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visible from Earth
working, pictures
will trickle back to
Earth over backup
antenna.
Galileo space probe
View from Voyager II
Voyager ,11 is so far out, Jupjterwould,
^ajjpear only about two pixels across
in its camera. Instead, other
‘inStrl/ntertis will be used to ‘
take measurements.
Source: Paul Chodas and David Seal, Jet Propulsion Laboratory; Dan Bruton, Texas A&M University
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Human virus may render heart disease treatment inefFective
WASHINGTON (AP) — Some blood
vessels treated with coronary angioplas
ty may become blocked again by a nat
ural reaction, a new study suggests.
The angioplasty treatment may be
neutralized by the action of a common
human virus against a gene that nor
mally prevents the formation of cancers.
Scientists at the National Institutes
of Health report today in the journal
Science that cytomegalovirus may de
activate the cancer-defense gene and
allow an overgrowth of smooth muscle
cells inside arteries that have been
opened by angioplasty, a procedure
that uses an inserted balloon to clear
clogged arteries.
Earlier studies have identified the
gene, called p53, as one of the body’s de
fenses against cancer. Studies have
shown that the gene’s normal function
is to limit the growth of cells. Missing or
deactivated p53 has been linked to
many human cancers.
Dr. Stephen E. Epstein, an NIH re
searcher, said the study in his lab
should be considered only preliminary
and not proof that the cytomegalovirus,
or CMV, is the culprit in closing the
treated arteries.
“We aren’t there yet (with proof),”
he said, “but the evidence does suggest
this as a possible mechanism for
restenosis (the re-closing of arteries)
after angioplasty.”
However, Baylor College of Medicine
virologist Dr. Joseph Melnick called the
NIH study “fascinating” because it indi
cates a possible link between cancer
and heart disease.
Patients with blocked arteries are
treated with coronary angioplasty. In
this procedure, a tube is threaded up
an artery until it comes to a site that is
blocked by a heart disease process. A
collapsed balloon is then threaded up
the tube and positioned at the block
age. The balloon is inflated and com
presses the plaque material that
caused the blockage. This allows blood
to flow freely.
But in more than 25 percent of angio
plasty patients, a blockage reforms at
the treated site, often leading to the
need for coronary artery bypass surgery.
The NIH team reasoned that the new
blockage may be caused by an uncon
trolled growth of smooth muscle cells
like those in the artery wall. Angioplas
ty often causes a slight injury to the
artery and the vessel then heals itself
by growing new cells.
It is possible, said Epstein, that the
injury somehow activates CMV parti
cles that are present, but latent, in the
artery. This virus, he said, could at
tach to p53 and then shut down the
gene’s action.
When p53 is deactivated, said Ep
stein, smooth muscle cells repairing the
artery are allowed to grow without re
straint, forming a new blockage.
“There are a lot of theories about
what causes this restenosis and ours is
just one of them,” said Epstein.
Q Cause heat stroke, the most dangerous
of the heat-related illnesses. Symptoms
include an inability to sweat, increased body
temperature, dizziness, fainting and loss of
consciousness.
Get help immediately. Remove as much
of the victim’s clothing as possible. Sponge
the skin with cool, not cold, water. Do not
force liquid if victim is unconscious.
Health Tips
Fitness fanatics beware obsessive regimens
By Lori Kuykendall
A.P. Beutel Health Center
Qj Cause heat exhaustion, the most
common heat-related illness. Symptoms
include clammy or sweaty skin, normal or
slightly elevated temperature, rapid pulse,
nausea and thirst.
Get out of the heat and rest. Restore
fluids by drinking slowly. Gently apply wet
towels to the body. Check with doctors to
see if salt or medication is needed.
£1 Cause heat cramps, the least serious
of heat-related illnesses that
untreated can lead to more serious
problems. Heat cramps usually occur after
exercise or physical labor. Symptoms
include sweaty skin, weakness or nausea,
tingling in the arms and legs.
^ Get out of the heat and rest. Drink cool
liquids. Check with a physician
to see if salt or medication is needed.
Cooling off;
D Reduce physical activity
E When outside, stay in shade
or wear wide-brimmed hat or
use umbrella.
E Use air conditioners or fans
or go to places that have them.
E Bathe or shower in cool
water.
E Drink plenty of liquids. Avoid
alcohol, coffee and tea or other
drinks that cause fluid loss.
E Do not take salt tablets.
APAVm. J. Gastello
Many Texas A&M students are putting
much of their time and energy into getting
and maintaining the “perfect body.”
Look in any of the local gyms from about
4 p.m. until midnight or watch all the peo
ple who are making no-fat or low-fat choic
es for meals and snacks.
As a young, well-educated population,
college students are generally considered
one of the healthiest segments of our nation.
Unfortunately, many students are be
coming overly concerned about health and
body image. Their drive to be healthy goes
too far.
The result can be compulsiveness and ob
session, which in turn can lead to a dangerous
eating disorder or other emotional problems.
It is easy to gradually acquire a miscon
ception of the difference between health
and thinness.
Often a desire to become healthy be
comes a desire to be too thin.
Such a crossover from health to exces
sive eating and exercise can occur for many
reasons.
Going away to college gives students a
chance to become who they want to be and
exercise new independence. A student
wants to get a new body image and be a
new person.
People trying to lose weight
should do so moderately over
time....They should not drop
below 1200 calories a day.
It is encouraging to be able to go home
for the holidays and have people give com
pliments about losing weight or having a
new “college image.”
Another cause of an over-obsession with
body image can be perfectionism.
Often overachievers struggle with an ex
treme drive for perfection in academic areas,
outside activities, and eating and exercising.
The danger comes when the balance shifts
from being “healthy” to being overly con
cerned and discontented about body image.
Any health textbook will define health as
a balance of physical, mental, social, spiritu
al and emotional well-being.
It is important to reach and maintain a
weight that will heighten physical health,
but it is equally important to attain emotion
al well-being.
Part of being healthy is accepting nat
ural body size. Most people cannot have
extremely thin bodies.
There will always be people smaller
than, and a lot of people bigger than, some
one else.
The key to a healthy diet is moderation.
Health professionals on not recommend ex
treme dieting and starvation as a healthy
way to lose weight.
A healthy diet is low in fat and consists
of food from the five food groups in the food
guide pyramid.
People trying to lose weight should do so
moderately over time, making permanent
lifestyle changes. They should not drop be
low 1,200 calories a day.
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