iSCIENCE
Gravity and
Microgravity
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Gravity
Gravity is the name Sir Isaac Newton
gave to the invisible force that keeps us
'glued' to planet Earth. It makes things fall
towards the heart of the Earth and not
float upwards. Gravity tugs on everything
with a 'mass', working a bit like a magnet.
All of the stars in the Universe, the
planets and their moons have gravity.
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MICROGravity
You would see some signs of total
weightlessness in an environment
with microgravity (written
“micro-g” or “µg”). But study
closely and the g-forces are not
actually zero, just microscopically
small, which means microgravity.
Plants In Space!
Experiments to test the effects of microgravity can be
carried out on the International Space Station, ISS. In
2004, Dutch astronaut André Kuipers grew seedlings on
board as part of the Seeds in Space project investigating
the effects of light and gravity.
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12 years later we have project “Rocket Science”. Huge
bags of rocket (lettuce) seeds were sent to the ISS ahead
of Tim Peake’s December 2015 arrival. The seeds will
spend several months in microgravity, then once back
down on Earth, thousands of UK schoolchildren will get
involved. They will plant, grow and carefully compare
any seedlings to a ‘control group’ of the same seed type
(‘cultivar’) that stayed on Earth.
(The doomed Falcon 9 rocket was carrying the first
batch of these seeds in June 2015...but don’t worry as
replacements went up on the Soyuz in September 2015.)
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