BBC Science Focus - 03.2020

Q&A

SACHINSHAW, VIA EMAIL

IS THERE ANYWHERE THAT’S

COMPLETELY BACTERIA-FREE?

Bacteriahave colonised the planet more thoroughly than

any other class of organism. They live 11km deep in the

Pacific Ocean, and at altitudes of 40km, near the top of the

stratosphere. There are bacteria that live in solid rock,

metabolising radioactive waste, and even some that survive

in boiling water. The incredibly dry Atacama Desert in Chile

was once thought to be lifeless, but in 2006 scientists found

bacteria there that take advantage of the minute amounts

of moisture absorbed from the air by salty rocks. In our

own environment, we can reduce the number of

bacteria but not eliminate them entirely. One

species has even evolved to survive the

rigorous sterilisation process used in NASA

clean rooms. In fact, probably the only

place on Earth that we can be

confident will always be entirely

bacteria-free is the lava

crater of an actively

erupting volcano. LV

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Planescan and have flown into space for over 50 years – though not the kind you
see at the airport. That’s because conventional planes need air for both propulsion
and lift, and space is essentially a vacuum.
The first plane to reach space was the X-15, designed in the mid-1950s for the US
National Advisory Committee for Aeronautics (NACA), forerunner of NASA. It made
its first flight in June 1959, using thin, stubby wings for generating lift and stability
while travelling at over five times the speed of sound, plus a revolutionary form of
rocket motor whose power output could be varied like a conventional aircraft
engine. In 1963, an X-15 using a propellant of oxygen and ethyl alcohol reached an
altitude of over 100km, widely recognised as the altitude at which space begins.
The lessons learned were fed into the Space Shuttle programme and today’s
commercial spaceplane ventures like Virgin Galactic.RM

JASONWEBB, TENNESSEE

WHY DOES SMELL AFFECT TASTE?

Strictly speaking, taste only occurs in the mouth, and

refers to one of the five basic sensations detected by

the taste buds – sweet, salty, sour, bitter and savoury

or ‘umami’. Your nose, however, detects aroma, which

can identify a much wider range of thousands of

volatile compounds. The sum of these two sensations

is what we perceive asflavour, and so both play an

important role in our overall experience of food.LV

DENNISROBERTSON, SHEFFIELD

WHY CAN’T WE FLY PLANES INTO SPACE?

TheX-15 was

the first plane to

reach space