21 September 2019 | New Scientist | 17TechnologyAstronomy RoboticsTwo new species of
electric eel foundIt was thought that there
was only one species of
electric eel. Now two more
have been discovered, one
of which (Electrophorus
voltai, pictured) delivers a
record jolt. All three species
are found in South America
and can produce between
650 and 860 volts
(Nature Communications,
doi.org/dbdr).Ancient kangaroos
had crushing bitesGiant ice age kangaroos
had “absurdly huge
cheekbones”, which
helped them munch tough
branches. The finding
came from creating a
digital model of a skull
of Simosthenurus
occidentalis, an extinct
kangaroo that lived until
around 42,000 years ago
(PLoS One, doi.org/dbdq).To w e r i s m a d e o f
self-shaping woodA method for producing
bent wooden panels could
make it easier to create
curvy buildings. The
technique involves the
use of wooden sheets
designed to bend as they
dry and has been applied
for the first time to build
a 14-metre-tall twisting
tower in Germany (Science
Advances, doi.org/dbh9).Free energy even
when the sun setsA DEVICE that makes electricity
at night using heat rising from the
ground could be used to power
lights and phones in remote spots.
More than 1 billion people
globally, chiefly in poor, rural
communities, still lack an
electricity supply. Cheap solar cells
are increasingly used to power
lights, mobile phones and home
appliances in these communities,
but they work only during the day.
Now, Aaswath Raman at theTHE centre of our galaxy has blown
some bubbles. Astronomers using
the MeerKAT telescope in South
Africa have found a pair of vast
balloons of high-energy particles
above and below the Milky Way’s
central supermassive black hole.
MeerKAT can detect synchrotron
radiation that is caused by charged
particles like electrons moving near
the speed of light. Farhad Zadeh at
Northwestern University in Illinois
and his colleagues used it to map
the area near our galaxy’s core.
They found two huge bubbles
protruding from the area around
the supermassive black hole at the
centre of the galaxy, perpendicularto the galactic disk (Nature,
doi.org/dbgn). They are just visible
as smoky smudges above and below
the bright central line of the galaxy
in the picture above.
The particles in them must have
been accelerated by a powerful
event at the middle of the Milky Way,
perhaps the black hole gobbling lots
of material and causing a big flare.
The bubbles may be related
to another cosmic mystery. More
than 100 filaments of magnetised
particles were discovered about
35 years ago, and we don’t know
how they formed or why they
emit radio waves. These strands
are within the bubbles. LCUniversity of California, Los
Angeles, and his colleagues have
invented a $30 device that makes
electricity at night using the
thermoelectric effect – in which
temperature differences can be
converted to electricity.
Raman and his team created
a temperature difference using
a mechanism called radiative sky
cooling, which causes sky-facing
surfaces to become colder than
the surrounding air as they
naturally radiate heat into the
sky. They constructed a box with
a black disc on the outside facing
upwards and an aluminium blockIs it a bird? Is it a fish?
No, a leaping waterbotLIKE a flying fish gliding above
the waves, a robot can propel itself
out of water into flight.
Mirko Kovac and his colleagues
at Imperial College London have
developed a robot that can lift
itself out of water and travel
through the air for up to 26 metres.
It weighs 160 grams and could be
used for monitoring the ocean,
taking samples by jumping in
and out of the water in cluttered
environments, avoiding obstacles
such as ice in cold regions or
floating objects after a flood.
The robot consists of a small
tank that refills with water from
its aquatic surroundings. It is
powered by calcium carbide, a
chemical powder that reacts with
water to produce combustible
acetylene gas. When the gas is
ignited by a spark, it expands,
pushing a jet of water out that
propels the robot into the air.
It can jump multiple times
after refilling with water, which
could allow it to take several
samples per trip.
The team tested the creation
in a lab, lake and wave tank. The
next stage is to see whether it
could be used to monitor the
oceans around coral reefs and
offshore energy platforms (Science
Robotics, doi.org/dbgk). Donna Luon the inside. The black disc was
designed to cool by losing heat
to the sky, while the aluminium
block was designed to warm up
by absorbing heat from the night
air. A thermoelectric generator
then converted the temperature
difference to electricity.
It produced 25 milliwatts of
power per square metre when
tested on a roof in California on a
clear night, enough to switch on
an LED light (Joule, doi.org/dbgm).
The output would probably be
20 times better in hotter climates,
says Raman. However, cloud and
rain may hinder it. AKGiant space bubbles found
near heart of the Milky Way
LEANDRO SOUSA
SOUTH AFRICAN RADIO ASTRONOMY OBSERVATORYReally brief
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