NEWS | IN DEPTH568 6 MAY 2022 • VOL 376 ISSUE 6593 science.org SCIENCElease animals for killing with the click of
a mouse, but now the software requires
the user to consider other options, such
as transferring animals to different labs
or using them for teaching purposes. Some
German scientists have even wanted to of-
fer unused genetically modified animals to
zoos to feed their creatures, although regu-
lations may prevent that.
Better matching the supply of research
animals to the demand could also reduce
cullings. CRISPR or other gene editors can
be used to create modified animals in a
single generation, without breeding sev-
eral generations of surplus animals. And
labs can substantially reduce the number
of animals killed by thawing frozen sperm
or embryos as needed, for example, rather
than creating populations of surplus ani-
mals to keep modified lines going.
Ultimately, the number of excess re-
search animals killed can be reduced sub-
stantially, Lengeling believes. “Maybe we
can halve it.”
Some institutions have reported prog-
ress. Goethe University Frankfurt says
that since 2017 the number of lab animals
not used for research decreased by almost
30%. Other German institutions contacted
by Science stress that they are trying to re-
duce those numbers as well.
It’s not clear whether the animal welfare
groups’ tactic will move beyond Germany,
as other countries have less strict animal
protection regulations and often less trans-
parency. In the United States, not even the
number of animals used for research is
known; estimates vary from 10 million to
more than 100 million annually. As a re-
sult, U.S. labs “can kill excess animals with
no need to justify (or count) numbers to
anyone other than the in-house ethics com-
mittee,” says veterinarian Larry Carbone,
a visiting fellow at the Animal Law & Pol-
icy Program of Harvard Law School.
In a few U.S. states, he notes, institutions
must try to find new homes for healthy lab
dogs and cats. For millions of genetically
modified mice and zebrafish, that’s hardly
an option, though.
Meanwhile Tuckermann, Lengeling, and
others are wondering what the criminal
complaints mean for the future of animal
research in Germany. They are calling on
German politicians to clarify the animal
protection regulations so they know when—
and whether—any culling is acceptable.
“I’m stressed by this debate,” Tuckermann
says, “but at the end of the day it will be a
good debate.” jHinnerk Feldwisch-Drentrup is a journalist based in
Berlin who also writes for Die Zeit, which is publishing
its own version of this investigation.Balloon detects first signs of
‘sound tunnel’ in the sky
Atmospheric analog to ocean’s acoustic channel could
be used to monitor eruptions and bombs
ATMOSPHERIC SCIENCEA
bout 1 kilometer under the sea lies
a sound tunnel that carries the cries
of whales and the clamor of subma-
rines across great distances. Ever
since scientists discovered this Sound
Fixing and Ranging (SOFAR) channel,
they’ve suspected a similar conduit exists in
the atmosphere.
Now, by listening to distant rocket
launches with solar-powered balloons, re-
searchers say they have finally detected hints
of one, although it does not seem to function
as simply or reliably as the ocean SOFAR. If
confirmed, an atmospheric SOFAR could help
researchers use aerial re-
ceivers to detect remote
explosions from volca-
noes, bombs, and other
sources that emit infra-
sound—acoustic waves
below the frequency of
human hearing.
“It would help enor-
mously to have those
[detectors] up there,” says William Wilcock,
a marine seismologist at the University of
Washington, Seattle. Although seismic sen-
sors in the ground pick up most of the plan-
et’s biggest bangs, “some areas of the Earth
are covered very well and others aren’t.”
In the ocean, the SOFAR channel is
bounded by layers of water that trap and
guide sound waves like bumpers in a bowling
lane. After geophysicist Maurice Ewing dis-
covered it in 1944, he set out to find an analo-
gous layer in the tropopause, a layer between
10 and 20 kilometers up in the atmosphere.
Like the marine SOFAR, the tropopause rep-
resents a cold region, where sound waves
should travel slower and farther. An acous-
tic waveguide in the atmosphere, Ewing
reasoned, would allow the U.S. Air Force to
listen for nuclear weapon tests detonated by
the Soviet Union. He instigated a top-secret
experiment, code-named Project Mogul, that
sent up hot air balloons equipped with infra-
sound microphones.
The instruments often malfunctioned
in the high winds, and in 1947, debris from
one balloon crashed outside of Roswell, NewMexico, sparking a famous UFO conspiracy
theory. Soon after, the military disbanded the
project, but it wasn’t declassified for nearly
50 years. By then, research in atmospheric
infrasound had all but died out, says Stephen
McNutt, a volcanic seismologist at the Uni-
versity of South Florida. “All of a sudden, the
rug got pulled out,” he says.
But Sarah Albert, a geophysicist at Sandia
National Laboratories in New Mexico, never
gave up on the idea. On 14 April 2021, she and
her colleagues launched a balloon at sunrise
from an airport near Albuquerque. They
timed the flight to coincide with the launch of
Blue Origin’s New Shepard rocket, which was
taking off more than 400 kilometers away in
Van Horn, Texas. Floating
at an altitude of about
20 kilometers, the bal-
loon picked up three clear
signals from the rocket—
one when it launched,
and two more when it
ascended and descended
through the tropopause,
the researchers revealed
last month at the annual meeting of the
Seismological Society of America. The ob-
servation marks the first verified infrasound
detection of a distant airborne source with an
airborne receiver, Albert says.
However, the team repeated the experi-
ment with another rocket launch in Califor-
nia on 27 September 2021 and saw no signal
at all. Although this new launch was three
times farther away than the one in Texas,
they still expected the channel to carry the
sound waves, Albert says. “I do believe that
there’s an atmo-SOFAR channel that exists,”
she says. “But I’m not as confident it ex-
ists all of the time, and that it can channel
sound as far as we had previously thought.”
Winds and temperature variations make
the tropopause much less stable than the
ocean channel, she adds.
Going forward, the researchers plan to
listen to launches with multiple balloons
staggered at different altitudes to figure out
where the channel’s effects are strongest. jZack Savitsky is a science journalist and graduate
student at the University of California, Santa Cruz.By Zack Savitsky“It would help
enormously to have those
[detectors] up there.”
William Wilcock,
University of Washington, Seattle0506NewsInDepth_15558970.indd 568 5/3/22 5:45 PM