Page 66 - All About Space 68 - 2017 UK

Life but not as we know itife but not as we know it
L

tRAppiSt-1 SyStEM

Life that’s

transferred in

collisions

In February of this year, the astronomical community
rejoiced at an announcement stating that a planetary
system of seven potentially habitable planets had been
discovered 39 light years away. Of these seven planets,
three of them have potential to hold liquid water, so
astronomers worldwide began working hard to uncover the
secrets of the TRAPPIST-1 system.
Since the discovery, research has shown that these seven
planets are closely packed together, with the outer planet
orbiting the host star at a distance of 0.06 Astronomical
Units (AU). An astronomical unit is the distance between
our Sun and the Earth, so to be at 0.06 AU makes it even
closer to its host star than Mercury is to the Sun. As the
TRAPPIST-1 star is a M-type dwarf, its size and intensity is a
fraction of our Sun's. This leads to the habitable zone – the
distance from a star where water can exist as a liquid –
being extremely close to the star.
This led to a group of astronomers at the University of
Chicago proposing that space debris, coated with bacteria
and single-celled organisms, could be transferred to the
other planets in the planetary system.
“Frequent material exchange between adjacent planets in
the tightly packed TRAPPIST-1 system appears likely,” says
Sebastian Krijt, an astronomer at the University of Chicago.
“If any of those materials contained life, it’s possible they
could inoculate another planet with life.”
So, if a meteor were to crash into one of the TRAPPIST-1
planets harbouring bacterial life, the space debris would
be consequently launched into space with remnants
of this bacteria. Before long, this debris would be at its
neighbouring planet, passing life on a whole new world.

© ESO/M. Kornmesser

66
66