18 | New Scientist | 22 June 2019Solar systemSolution to snack
waste is in the bagA NEW kind of wrapping could
soon solve the problem of crisp
packet waste.
When people started posting
their packets back to crisp
manufacturer Walkers to protest
that they weren’t easily recycled,
the firm took notice and launched
collection points for them. But this
special scheme has recovered just
3 million of the 4 billion bags the
company sells annually in the UK,A regular visit to the
park is good for youCLOCKING up at least 2 hours a
week in green spaces such as
parks and woodlands is enough
to improve health and happiness.
The benefits of being out in
nature have been well-
documented, but until now no
one has quantified how much
time might be beneficial. Mathew
White at the University of Exeter,
UK, and his colleagues came up
with the 2-hour minimum by
analysing a survey of 20,000
people in England, who reported
how long they spent in natural
environments in the past week,
plus their health and well-being.
People who spent less than
2 hours in nature were no more
likely to report good health or
well-being than those who spent
no time there at all. Those who
spent more than that had
consistently higher health and
well-being levels, although aboveMental health RecyclingHOPES of one day finding living
things on Jupiter’s moon Europa
have been given a boost. Sodium
chloride, or table salt, spotted on its
surface could mean that its buried
ocean has a composition similar to
seas on Earth and so is good for life.
We have known for a long time
that Europa has salts on its surface,
but early observations suggested
they were sulphates resulting from
interactions between sulphuric
acid and other compounds.
Samantha Trumbo at the
California Institute of Technology
and her colleagues used the Hubble
Space Telescope to examine the icy
moon’s surface chemistry. They
found signs of sodium chloride
turning the surface yellow as it
was hit with radiation from space.
The strongest of these signals
came from Tara Regio, a part ofthe moon thought to be shaped
by water seeping up from the
subsurface ocean. That indicates
that the salt could be coming from
within Europa, hinting at the ocean’s
chemical composition (Science
Advances, doi.org/c677).
We have never actually detected
an ocean with primarily sulphates
for salts, says Trumbo. “If it’s
sodium chloride instead, that means
it’s more like Earth. If you licked it,
it would probably taste familiar.”
That is a good sign, in terms
of looking for life. Earth’s oceans
are the only ones in the universe
that we know to be habitable.
The subsurface ocean of Saturn’s
moon Enceladus has many of the
necessary ingredients for life, such
as complex organic molecules, and
is also full of sodium chloride.
Leah CraneEuropa’s hidden ocean may
be briny and ripe for life
and they still aren’t accepted by
household recycling schemes.
The root of the problem is
that the metallised films used
for packaging crisps and many
other foods are great for keeping
contents dry and cool, but hard
to recycle.
Now Dermot O’Hare at the
University of Oxford and his
team have come up with an
alternative. It is a thin layer, called
a nanosheet, made from amino
acids and water. This is applied to
a film of PET, the plastic used to
make most water bottles.
The nanosheet’s benign
building blocks appear to result
in a material safe for use with
food and that can be widely
recycled, says O’Hare.
Crucially for such packaging,
it is a good barrier to gases and
survives crumpling. But O’Hare
says that a long regulatory process
means it will be at least four years
before the material reaches shop
shelves (Nature Communications,
doi.org/c679). AV2 hours, the benefits seem to give
diminishing returns. No further
gain in well-being was detected
after 5 hours. This could be
because such times are clocked
up by dog walkers who have little
choice in the matter, says White.
He says spending 2 hours in
nature can be spread over a week.
This should be possible for most
people: the average person already
clocks up 94 minutes a week.
The team controlled for the fact
that the health benefits might be
a byproduct of physical activity,
not contact with nature. The
magnitude of the benefit of the
2 hours seems to be significant, on
a par with the health differences
associated between living in a
well-off area and a deprived one.
The benefits seem to apply
to everyone, regardless of age,
gender, long-term illness or
disability (Scientific Reports,
doi.org/c69k). “You don’t have
to be running around the park,
just sitting on a bench will do,”
says White. Adam VaughanNA
SA
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JACK^ SULLIVAN/ALAMYNews In brief