Scientific american (April 2003)

86 Pages·2003·3.35 MB·English

by  Scientific American

SOLVING THE NEUTRINO MYSTERY • RECOGNIZING ANCIENT LIFE
APRIL 2003 $4.95
WWW.SCIAM.COM
James D.Watson discusses
DNA, the brain, designer babies
and more as he reflects on
Grid Computing’s
Unbounded Potential
Ginkgo Biloba Will Mount Etna
and Memory Explode Tomorrow?
Delivering Drugs
with Implanted Chips
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
contents
april 2003
features
SCIENTIFIC AMERICAN Volume 288 Number 4
ASTROPHYSICS
40
Solving the Solar Neutrino Problem
BY ARTHUR B. MCDONALD, JOSHUA R. KLEIN AND DAVID L. WARK
After 30 years, physicists fathom the mystery of the missing neutrinos:
the phantom particles change en route from the sun.
BIOTECHNOLOGY
50
Where a Pill Won’t Reach
BY ROBERT LANGER
Implanted microchips, embedded polymers and ultrasonic blasts of proteins
will deliver next-generation medicines.
66James D. Watson
VOLCANOLOGY
58
Mount Etna’s Ferocious Future
BY TOM PFEIFFER
Europe’s most active volcano grows more dangerous, but slowly.
CELEBRATING THE GENETIC JUBILEE
66
A Conversation with James D. Watson
The co-discoverer of DNA’s double helix reflects on the molecular model
that changed both science and society.
LIFE SCIENCE
70
Questioning the Oldest Signs of Life
BY SARAH SIMPSON
Researchers are reevaluating how they identify traces left by life
in ancient rocks on earth—and elsewhere in the solar system.
INFORMATION TECHNOLOGY
78
The Grid: Computing without Bounds
BY IAN FOSTER
Powerful global networks of processors and storage
may end the era of self-contained computing.
MEDICINE
86
The Lowdown on Ginkgo Biloba
BY PAUL E. GOLD, LARRY CAHILL AND GARY L. WENK
This herbal supplement may slightly improve your
memory—but so can eating a candy bar.
Also:Mark A. McDaniel, Steven F. Maier and
Gilles O. Einstein discuss other “brain boosters.”
www.sciam.com SCIENTIFIC AMERICAN 7
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
SCIENTIFIC AMERICAN Volume 288 Number 4
departments
10 SA Perspectives
Get real about abstract worries.
12 How to Contact Us
12 On the Web 28 100
16 Letters
20 50, 100 & 150 Years Ago
34 Innovations
22 News Scan
Metanomics develops a way to peek
■ Manned spaceflight after Columbia.
into plant metabolism.
■ Spilled oil off Spain’s coast proves too slippery
to predict. 37 Staking Claims
■ Bacteria thawed an ancient earth. The case for restricting patents that hinder basic
■ Suspicions about the speed of gravity. biomedical research.
■ Do gray wolves still need protection? 92 Working Knowledge
■ More proof that “clone” doesn’t mean “copy.”
Patches that deliver drugs.
■ By the Numbers: Poverty in the U.S.
94 Technicalities
■ Data Points: Invasive species.
Tablet PCs are high-tech tools for scribblers.
97 Reviews
Faster Than the Speed of Light looks provocatively
at the new cosmology.
94
columns
38 Skeptic
BY MICHAEL SHERMER
The Three Laws of Cloning.
100 Puzzling Adventures
BY DENNIS E. SHASHA
Graphing the origins of species.
102 Anti Gravity
BY STEVE MIRSKY
Burgers and joints.
103 Ask the Experts
What is the importance of the new discovery?
104 Fuzzy Logic
BY ROZ CHAST
Cover image by Mike Medicine Horse, Hybrid Medical Animation
Scientific American (ISSN 0036-8733), published monthly by Scientific American, Inc., 415 Madison Avenue, New York, N.Y. 10017-1111. Copyright © 2003 by Scientific
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Harlan, Iowa 51537. Reprints available: write Reprint Department, Scientific American, Inc., 415 Madison Avenue, New York, N.Y. 10017-1111; [phone];
fax: [phone] or send e-mail to [email protected] Subscription inquiries: U.S. and Canada [phone]; other [phone]. Printed in U.S.A.
8 SCIENTIFIC AMERICAN APRIL 2003
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SA Perspectives
Get Real
When the cloning of a human was announced last The answer from technocynics is yes. In his book last
December, political and spiritual leaders condemned year Fukuyama drew a line between medical therapy
it as an affront to the “dignity of man.” That kind of (OK) and genetic enhancement (not OK) but went on
rhetoric is popping up all over the place. Political sci- to advocate a ban on all cloning, even the therapeutic
entist Francis Fukuyama warns that genetic engineer- kind. Similarly, Joy has called for a “relinquishment”
ing and Prozac-like drugs augur “a ‘posthuman’ stage of all—all—research into robotics, nanotechnology
of history.” Bill Joy, co-founder of Sun Microsystems, and genetic engineering. Where does this absolutist
frets over robotics and nanotechnology: “On this path stand leave the rest of us? We have watched our par-
our humanity may well be lost.” ents and grandparents waste away from cancer and
Even theEconomist,a magazine Alzheimer’s disease. We have seen children die of dia-
not usually given to apocalyptic betes and friends fall to depression, malaria and HIV.
predictions, worries that neuro- If it comes down to a choice between the vague unease
science could “gut the concept of that emerging technologies conjure up or the very un-
human nature.” vague suffering they could cure, we know how we
Like their counterparts in would decide.
earlier ages, these commentators The technocynics basically want us to grin and bear
argue that technology is running it, lest our attempts at self-improvement do more harm
ahead of our ability to deal with than good. Yet if history is any guide, fears about the
ANXIETYover genetically it; although scientific progress is impact of new technologies generally wind up sound-
modified food often reflects all well and good, we have to rein ing pretty silly. Thoreau regarded trains, telegraphs,
abstract worries about science.
it in. Such views are often called newspapers and even mail delivery as dehumanizing.
neo-Luddism, but frankly, that Late Victorians predicted that industrialization and ur-
does not do justice to the Luddites. Those machine- banization would cause our species to degenerate to a
smashing textile workers were reacting to immediate prehuman state. In the 1970s critics of in vitro fertil-
threats, such as losing their jobs. Today’s concerns ization said it would create monstrous or deranged ba-
tend to be abstract, and that is their problem. bies. In all these cases, abstract worries gave way to
A science magazine is all in favor of abstract think- mundane ones. New technologies did bring new prob-
ing, but at some point abstraction needs to make con- lems, but people worked around them. Few would, in
tact with reality. And the reality of research bears little retrospect, ditch the technologies altogether.
resemblance to the technocynics’ horror stories. Will The biggest danger, then, is not that science will run
cloning, for example, open the door to “designer ba- ahead of ethics, but the opposite: that ethical hair trig-
a
bies”? Maybe one day. For now, though, researchers gers will paralyze worthy research. Striking a balance m
g
y
are struggling to develop cloning just to grow tissues that is not easy. Bioethicist Gregory Stock offers a sound s S
bi
a patient’s immune system won’t reject. Even would-be prescription: “We should deal with actual rather than or
C
baby cloners don’t purport to fiddle with the genome. imagined problems.” To stop research is to give up try- HIG
U
Are people supposed to give up the prospect of life- ing to make the world a better place. It denies human O
N T
saving therapies to avoid a distant, hypothetical threat? nature in order to save it. O
SI
THE [email protected]
10 SCIENTIFIC AMERICAN APRIL 2003
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Letters
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Established 1845
EDITOR IN CHIEF:John Rennie IF APRIL IS THE CRUELEST MONTH,December may
EXECUTIVE EDITOR:Mariette DiChristina make us feel the most reflective, as we recall the past
MANAGING EDITOR:Ricki L. Rusting
NEWS EDITOR:Philip M. Yam year’s events. So it was with the December 2002 Per-
SPECIAL PROJECTS EDITOR:Gary Stix spectives, “In Science We Trust.” The column reviewed
REVIEWSEDITOR:Michelle Press
some of the achievements—and regrettable setbacks—of
SENIOR WRITER:W. Wayt Gibbs
EDITORS:Mark Alpert, Steven Ashley, science, which the editors nonetheless praised for “its in-
Graham P. Collins, Carol Ezzell, cremental progress toward a more complete understand-
Steve Mirsky, George Musser
CONTRIBUTING EDITORS:Mark Fischetti, ing of the observable world.” The commentary resonated
Marguerite Holloway, Michael Shermer, with many, including James Edgar of Melville, Saskatch-
Sarah Simpson, Paul Wallich
ewan, who responded: “I think I’ll photocopy your editori-
EDITORIAL DIRECTOR, ONLINE:Kate Wong al and add it to my collection of wise words—a collection
ASSOCIATE EDITOR, ONLINE:Sarah Graham
WEBDESIGN MANAGER:Ryan Reid that helps me to explain my beliefs about science, astronomy, evolution and life.” Other
ART DIRECTOR:Edward Bell writers express their beliefs concerning the December issue on the following pages.
SENIOR ASSOCIATE ART DIRECTOR:Jana Brenning
ASSISTANT ART DIRECTORS:
Johnny Johnson, Mark Clemens
PHOTOGRAPHY EDITOR:Bridget Gerety POLLOCK’S FRACTALS
PRODUCTION EDITOR:Richard Hunt I don’t understandsome aspects of “Order in Pollock’s Chaos,” by Richard
COPY DIRECTOR:Maria-Christina Keller P. Taylor. If the computer measures squares in Jackson Pollock’s works that have
COPY CHIEF:Molly K. Frances
paint in them and those that don’t, I don’t think that the numerical ratio between
COPY AND RESEARCH:Daniel C. Schlenoff,
Rina Bander, Shea Dean, Emily Harrison the haves and the have-nots would change, no matter the scale.
EDITORIAL ADMINISTRATOR:Jacob Lasky The second thing that bothers me is the straight-line graph, when squares
SENIOR SECRETARY:Maya Harty from 10 to zero millimeters are analyzed. Paintings are not like computer frac-
ASSOCIATE PUBLISHER, PRODUCTION:William Sherman tals, in which the locations of edges can be determined at every scale. At such
MANUFACTURING MANAGER:Janet Cermak
sizes, I cannot imagine how one would know where the edge of the line is, giv-
ADVERTISING PRODUCTION MANAGER:Carl Cherebin
PREPRESS AND QUALITY MANAGER:Silvia Di Placido en that paint bleeds, runs, is absorbed by the surface and mixes with other col-
PRINT PRODUCTION MANAGER:Georgina Franco
ors. It would seem, too, that the hills and valleys of the canvas would become
PRODUCTION MANAGER:Christina Hippeli
CUSTOM PUBLISHING MANAGER:Madelyn Keyes-Milch the dominant features. Also, if a photograph of the painting was scanned into
ASSOCIATE PUBLISHER/VICE PRESIDENT, CIRCULATION: the computer, doesn’t the analysis exceed the resolution capabilities of the pho-
Lorraine Leib Terlecki tograph and the scanner?
CIRCULATION DIRECTOR:Katherine Corvino
Michael Burke
CIRCULATION PROMOTION MANAGER:Joanne Guralnick
FULFILLMENT AND DISTRIBUTION MANAGER:Rosa Davis New York City
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ASSOCIATE PUBLISHER:Gail Delott TAYLOR REPLIES:The fractal character of a pattern does in fact reveal itself through
SALES DEVELOPMENT MANAGER:David Tirpack
the way the number of filled squares changes with magnification. For something to be
SALES REPRESENTATIVES:Stephen Dudley,
Hunter Millington, Stan Schmidt, Debra Silver fractal, the number of filled squares, N, must scale with the square length, L, accord-
ASSOCIATE PUBLISHER, STRATEGIC PLANNING:Laura Salant ing to the power law relation N ∼L–D. D is the fractal dimension—it quantifies the scal-
PROMOTION MANAGER:Diane Schube ing relation among the patterns observed at different magnifications. This power law
RESEARCH MANAGER:Aida Dadurian
PROMOTION DESIGN MANAGER:Nancy Mongelli relation is true also for smooth Euclidean shapes. The distinguishing property is that
for a smooth Euclidean line D = 1, whereas for a fractal line 1 < D < 2.
GENERAL MANAGER:Michael Florek
BUSINESS MANAGER:Marie Maher Regarding the second point: as noted in the text, we examine the fractal behavior
MANAGER, ADVERTISING ACCOUNTING over a range from about a meter down to a millimeter. For the fakes, the biggest distor-
AND COORDINATION:Constance Holmes
tion away from fractal behavior occurs at the small scales. After we established the frac-
DIRECTOR, SPECIAL PROJECTS: Barth David Schwartz
tal character of Pollock’s paintings, we then went back to the film to determine the phys-
MANAGING DIRECTOR, SCIENTIFICAMERICAN.COM:
ical processes that created them. For large scales, the key was in the way that Pollock
Mina C. Lux
moved around the canvas (he actually followed motions called Levy flights). At smaller
DIRECTOR, ANCILLARY PRODUCTS:Diane McGarvey
PERMISSIONS MANAGER:Linda Hertz scales (10 centimeters and below), the fluid dynamics become important: how the paint
MANAGER OF CUSTOM PUBLISHING:Jeremy A. Abbate was launched from the brush, how it fell and how it seeped into the canvas.
CHAIRMAN EMERITUS:John J. Hanley Fractals in the real world are different from mathematical fractals: they can’t go
CHAIRMAN:Rolf Grisebach
on forever. In fact, most fractals in nature continue over a magnification range of only
PRESIDENT AND CHIEF EXECUTIVE OFFICER:
Gretchen G. Teichgraeber about 20 times. Pollock is extraordinary in this regard, because his fractals are chart-
VICE PRESIDENT AND MANAGING DIRECTOR, ed over a magnification of 1,000 times! His patterns are fractal down to the finest
INTERNATIONAL:Charles McCullagh
VICE PRESIDENT:Frances Newburg speck of paint, about one millimeter in size.
16 SCIENTIFIC AMERICAN APRIL 2003
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Letters
Finally, we use high-resolution images in 0.001 millisecond for a burst source at one act for “the good of the species”—a notion
which distortion doesn’t occur until 0.8 mil- billion light-years observed between 100 and that has long been shown to be false. If one
limeter. Also, before sending images through 300 keV; such small lags were undetectable can speak of a “goal” for individual or-
the computer, we visually inspect them for by BATSE. Also, quantum gravity predicts that ganisms, it would be to maximize their ge-
any distortions caused by bumpiness. higher-energy photons lag behind lower-ener- netic contribution to future generations.
gy ones—contrary to the effect seen by BATSE. Don Luce
LAGGING PHOTONS? The quantum gravity lags would be easi- Bell Museum of Natural History
I read with interestthe Profile of Fotini erto observe at GeV energies. We are excit- Minneapolis
Markopoulou Kalamara [“Throwing Ein- edly awaiting the 2006 launch of the Gam-
stein for a Loop”], by Amanda Gefter, and LEONARD REPLIES:I did not mean to imply
the article “The Brightest Explosions in that organisms act for the good of the spe-
the Universe,” by Neil Gehrels, Luigi Piro cies. It’s true that an individual’s motivation
and Peter J. T. Leonard. I was particular- is to maximize its own reproductive success.
ly intrigued by the following quotations. That said, from the long-term lens of evolu-
From the Profile: “One experiment could tion (and the perspective of the population),
be to track gamma-ray photons from bil- the act of individuals allocating energy to the
lions of light-years away. If spacetime is next generation is what enables species to
in fact discrete, then individual photons persist and succeed.
should travel at slightly different speeds,
depending on their wavelength.” From 3-D MEMORIES
the article: “Roughly 90 of the [gamma- Memory is plastic,as Mark Alpert demon-
ray] bursts seen by BATSE [the Burst and strates in Technicalities [“Getting Real”]
Transient Source Experiment onboard when he recalls viewing the 1983 film
the Compton Gamma Ray Observatory] Jaws 3-D through cardboard goggles
form a distinct class of their own, defined GAMMA-RAY BURSTproduces intriguing photons. with red and blue filters. He’s describing
by ultralow luminosities and long spec- the anaglyph process, which used one red
tral lags, meaning that the high- and low- ma-ray Large Area Space Telescope (GLAST), filter and one green (or blue) one for 3-D
energy gamma-ray pulses arrive several with the hope that it will detect such lags in viewing of projected monochrome images.
seconds apart. No one knows why the gamma-ray bursts. The process used in Jaws 3-D, how-
pulses are out of sync.” ever, was different; it permitted stereo-
This may just be coincidence. I have YOU WIN SOME ... scopic projection in full color. It employs
no idea what Markopoulou Kalamara’s I really enjoyedthe “Scientific American polarizing filters at the projector and gog-
theories suggest the arrival-time differ- 50.” A once-a-year summary of major gles with polarizing filters.I also remember
ence should be for various wavelengths developments is a great way to get the big red and blue goggles from a series of 3-D
of photons, and there must be myriad picture. Don’t change it (much) next year! Batman comic books in the early 1960s,
possible explanations for the BATSE re- Mike Steiner however. Maybe the lenses Alpert re-
sults. But it struck me. via e-mail members were not from a movie at all.
Jonathan Leete Tom Flynn
Arlington, Va. As a longtime subscriber, I have never Buffalo, N.Y.
seen so much space wasted as in the “Sci-
GEHRELS AND LEONARD REPLY:The spec- entific American 50.” Surely you can find ALPERT REPLIES: You’re absolutely right.
tral lags observed in gamma-ray bursts by better articles. I hope this won’t be an an- That’s what happens when you read too many
BATSE are quite different from what is pre- nual waste. comic books.
dicted by quantum gravity. The BATSE lags Peter Tiley
observed between energies of 100 and 300 Dundas, Ontario ERRATUMIn “On Thin Ice,” by Robert A. Bind-
kilo-electron-volts (keV) ranged up to sever- schadler and Charles R. Bentley, a statement
al seconds in length, with higher-energy pho- SECRETS OF SPECIES SUCCESS about global warming should have read:
tons arriving before lower-energy ones. In “Food for Thought,”William Leonard “Around the world, temperatures have risen
CK But quantum gravity predicts an effect on states that “the goal of all organisms is the gradually since the end of the last ice age, but
LI
AR the order of about three milliseconds per same: to devote sufficient funds to repro- the trend has accelerated markedly since the
G
A. giga-electron-volt (GeV) per billion light-years duction to ensure the long-term success of mid-1900s”; we mistakenly printed “since
K
AR distance. This amounts to a lag of less than the species.” This implies that individuals the mid-1990s.”
M
www.sciam.com SCIENTIFIC AMERICAN 19
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50, 100 & 150 Years Ago
FROM SCIENTIFIC AMERICAN
The Wily Flu Frozen Continent Fishy Aviation
■ ■
APRIL 1953 A MASSIVE SEARCH—“The elementary ber 2 two sledge parties were sent out.
INFLUENZA VS. IMMUNITY—“The sero- particle corresponding to the gravita- The best record made was that of Capt.
logical character of the A virus has tional field has been named the graviton. Robert F. Scott, Dr. Edward Wilson, and
changed seven or eight times since 1933, There can be little doubt that in a formal Lieut. Ernest Shackleton. These intrepid
and each change in character has within mathematical sense the graviton exists. explorers traveled 94 miles to the south,
a year been evident all over the earth. However, nobody has ever observed an reaching land in latitude 80 deg. 7 min.
Soon after influenza A2 was found in the individual graviton. Because of the ex- This is the most southerly point yet at-
U.S., it appeared in Australia and En- treme weakness of the gravitation inter- tained. The expedition proved a most se-
gland as well. After it had taken hold, no action, in practice only large masses pro- vere test of the endurance of both men
A1 strains were found anywhere. And so duce observable gravitational effects. In and animals. All the dogs perished, so
for each successive change. It is a parasite the case of large masses, the number of that several men had to drag the sledges
back. Lieut. Shackleton almost died from
exposure.”
EASIER RIDER—“The increasing interest
in motor bicycles manifested of late
among cyclists is directly attributable to
the numerous improvements which have
brought various makes of these machines
up to a high standard of excellence. The
‘Indian’ motocycle is one type of machine
which has become quite popular in the
cycling world. Great care has been exer-
cised in the construction of the motor
used in this machine, and by thorough
testing under all conditions, it has been
brought up to a high state of efficiency.”
[Editors’ note: Before World War I, the
Indian Motocycle Company was the larg-
est manufacturer of motorcycles in the
world.]
THE INDIANmotor bicycle, 1903
APRIL 1853
whose only natural host is man. To sur- gravitons involved in the interaction is FLIES LIKE A FISH—“Theodore Poesche
vive, it must pass continually from one very large, and the field behaves like a has presented a plan for navigating the
human being to another—it is inhaled classical field. Consequently, many physi- atmosphere with a car propelled by a
and lodges in the respiratory tract. But it cists believe that the individual graviton steam engine without employing a bal-
soon finds itself in the position epidemi- never will be observed. Whether the loon. His plan is to build a long, narrow,
ologists call ‘exhaustion of susceptible graviton has a real existence is one of the and light wooden vessel, with wings of
hosts.’ In other words, almost the entire most important open questions in phys- canvas, and propel it by a screw propeller
population becomes immune. This high- ics. —Freeman J. Dyson” driven by steam power. ‘My ship,’ he
ly transmissible virus meets the situation says, ‘most nearly resembles the flying
by a transformation of character—a mu- APRIL 1903 fish, which progresses by the spiral action
tation that enables it to overcome its BRAVING ANTARCTICA—“Reports say the of the tail, while its extended fins support
host’s immunity. —Sir Macfarlane Bur- ‘Discovery’ entered the ice pack Decem- it in the air.’ The screw propeller was
net” [Editors’ note: Burnet was a co-win- ber 23, 1901, in latitude 67. On March proposed long ago to drive aerial ships
ner of the 1960 Nobel Prize for Physiol- 24 the ship was frozen in, but the expe- with balloons, but could not do it then,
ogy or Medicine “for discovery of ac- dition passed a comfortable winter near and to do so now without a balloon is an
quired immunological tolerance.”] Mounts Erebus and Terror. On Septem- impossibility.”
20 SCIENTIFIC AMERICAN APRIL 2003
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news
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Rethinking the Shuttle
IN FUTURE MANNED FLIGHTS, SMALLER WILL BE SAFER BY MARK ALPERT
A
s NASA investigates why Columbia repairing damage while in orbit. But if the ac-
broke up during its reentry into the at- cident’s cause cannot be pinpointed or if a
mosphere on February 1, killing all major redesign of the three remaining shut-
seven astronauts onboard, the space agency tles is required, NASAmay have to accelerate
faces some difficult choices. For more than a its development of a smaller, more reliable
decade, aerospace experts had warned about spacecraft.
the vulnerability of the aging, 100-ton space Previous efforts to replace the shuttle fleet
shuttles to the superheated gases that envel- have been expensive failures [see “Has the
op the craft as they descend to Earth. If in- Space Age Stalled?” by Mark Alpert; Scien-
vestigators determine that a breach in Co- tific American, April 2002]. Last Novem-
REENTRY TRAGEDY: lumbia’s heat shield or aluminum skin ber the agency committed $2.4 billion to pro-
Fallen debris from the space
doomed the mission, NASA might require ducing a design for an orbital space plane
shuttle Columbia leans against
shuttle crews to inspect the craft’s exterior be- (OSP) that could ferry a crew of at least four
a fence near Douglass, Tex.
fore reentry and perhaps devise a strategy for astronauts to the International Space Station.
(With the shuttles grounded, NASAlost access
to the station; only the Russian Soyuzand
Progressspacecraft can ferry crews and sup-
plies to the orbital outpost.) NASA’s plans,
however, are still vague; the agency has not
yet decided whether the OSP will be a winged
vehicle like the shuttle, a lifting body (a squat
craft shaped to maximize aerodynamic lift),
or a capsule like Soyuz. And even if Congress
approved an additional $10 billion to build the
space plane, it would not be ready to carry
crews into orbit until 2012. Dennis E. Smith,
o
manager of the OSP program, is looking for hot
P
ways to speed up the schedule, but he cautions, AP
M
“I don’t think we can save a lot of time.” LIA
L
The orbital space plane promises to be WI
MC
much safer than the shuttle. The OSP would A
N
hold only astronauts, not heavy cargo, so it ON
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22 SCIENTIFIC AMERICAN APRIL 2003
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
news
is that it could not perform all the shuttle’s SCAN
tasks. NASAwould have to develop an un-
manned launch and docking system to send
heavy payloads to the space station. And the
OSP would have its own risks, of course. The
safety record of even the most successful rock-
ets is not perfect—the Delta 2, for example,
has carried payloads into orbit 104 times
since1989 but did explode once, in 1997.
NASAwould need to extensively test and up-
FOUR DESIGNS for the orbital space plane (clockwise
from top left): lifting body; winged vehicle with sharp grade the boosters chosen to launch the OSP.
leading edges; shuttlelike vehicle; and capsule, which To minimize the dangers of atmospheric
may be the safest for reentry. reentry, the best design choice for the OSP A NEW VEHICLE
FOR ASTRONAUTS
may be a capsule shape. According to Theo-
would be compact and light enough to be dore A. Postol, a space systems expert at the
Boeing, Lockheed Martin, and a
launched by a single-use commercial rocket Massachusetts Institute of Technology, a
team consisting of Orbital Sciences
such as the Delta 4. The shuttle, in contrast, blunt capsule falling through the atmosphere
and Northrop Grumman have
requires three rocket engines built into the ve- heats up much less than a winged vehicle already begun work on preliminary
hicle, an external tank of liquid hydrogen and does. And by eliminating wings, wheels and designs for the orbital space plane.
oxygen to feed those engines, and a pair of control surfaces, engineers could devote more The design proposed by Orbital
Sciences is based on the HL-20
solid-fuel boosters. of the craft’s mass to the all-important ther-
Lifting Body, a vehicle concept that
The immense strain of a shuttle launch in- mal shield. After descending to the lower at-
NASA studied in the early 1990s.
vites hazards: a leak in a solid-fuel booster mosphere, the capsule could float on para- The space plane would be about 37
caused the loss of the shuttle Challengerin chutes to an ocean landing, just as the Apol- feet long (compared with 122 feet
1986, and a piece of foam insulation falling lomodules did in the 1960s. “Given all those for the shuttle) and have a
wingspan of about 35 feet
from the external tank may have damaged benefits, is it really worth landing on a run-
(compared with 78 feet for the
Columbia’s left wing shortly after its launch way?” Postol asks.
shuttle). It could carry a crew of
on January 16. The smaller size of the OSP NASAofficials, though, do not seem en- five astronauts to and from the
would also reduce the chance of a collision thusiastic about the capsule design. Smith, the International Space Station (the
with micrometeoroids and man-made debris OSP manager, expresses concern about the shuttle typically carries seven).
Also, one of the space planes could
while the craft is in orbit. (Such debris could reliability of parachute mechanisms and
be continuously docked to the
have struck Columbia during its final mis- the cost of retrieving the spacecraft from the
EPT sion.) And the OSP’s heat shield could be ocean. Postol thinks a different factor may setmaetirogne ninc yca esvea citu iast nioene.ded for
C
ON fashioned from newly developed metallic explain the agency’s reluctance: “I expect that
A ARTIST C ptlaen’se plsa, tmchawkionrgk i to mf coerrea rmesiicl iteinlets t.han the shut- rNeAasSoAnws. iTllh ree saissttr othnea uctasp wsualnet ftoo rfl eym thoet ivoenhai-l Aowndwd ewsd. saitcgoiara’ismn sc.cot omCmoml,u eumnntbdaiearry at ahpbepoeuatr sth aet
AS The main disadvantage of the space plane cle.” Even if that makes for a riskier reentry. “Explore” link.
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R Oiling Up Spain
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A SUNKEN TANKER COULD TARNISH SPAIN FOR DECADES BY LUIS MIGUEL ARIZA
T
housands of tonsof heavy fuel remain toxic fuel have oozed from 20 cracks in the
in the bow and stern sections of the hulls as semisolid black strings, like tooth-
Prestige, the oil tanker that split in half paste being squeezed from a tube, and have
off the northwestern coast of Spain on No- drifted toward the sea surface. It has become
vember 19, 2002. It sank to the seabed, more Spain’s worst ecological disaster ever, halting
than 3,500 meters deep in the Atlantic Ocean coastal fishing and polluting beaches. The
some 200 kilometers from Galicia. Tons of ship has already spilled at least 30,000 tons
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