Page 21 - BBC Sky at Night - September 2017 UK

A PASSION FOR SPACE SEPTEMBER 21

A PASSION FOR

with Maggie Aderin-Pocock
The Sky at Night presenter hunts for space rocks

not on Antarctica, but on a roof in Sidmouth

Þ Maggie climbed onto the roof of the Norman Lockyer Observatory to search for tiny micrometeorites in the detritus collecting there
t’s classic thriller movie material: a still feels like a long shot. I am told by description of a micrometeorite but it is
comet or asteroid is heading straight my hunting guide Matt Genge not to small – just 10µm in diameter, less than
for Earth and only one person can expect much: he usually totals around the diameter of a human hair As the
Isave us. In reality, however, the 10 micrometeorites per 30kg of roof muck. micrometeorites hit our atmosphere they
majority of stuff that lands on Earth from heat and melt, forming a droplet of molten
space is really quite small and does us no Sludge science metal. As these fall through our atmosphere
harm at all. It may even have been the We collect about a dessert spoon’s worth, they cool, forming dendritic crystalline
precursor to life on the planet. so I’m not holding my breath. The sludge structures that look like feathers. The cone
Some 40,000 tonnes of space rock lands we’ve gathered is dried in a conventional is formed due to friction with the air.
on Earth every year, in a range of size oven, then a magnet is passed over it to There’s still one last check to make:
– scientists often make pilgrimages to pick up any magnetic material it might some pollution from smelting plants and
far-flung corners of the Earth to find contain. The stuff we end up with is similar processes can look like our
specimens. Antarctica is good spot: metal attached to some double sided sticky tape potential micrometeorite. So with the
meteorites that have been burnt by our and then analysed using a semi-portable microscope we do a chemical analysis, and
DENNIS KUNKEL MICROSCOPY/SCIENCE PHOTO LIBRARY sounds like an ideal place to look, so why potential candidate micrometeorite certain that this is a micrometeorite.
scanning electron microscope.
this gives us more evidence that we have
atmosphere stand out nicely against
the sheer white expanse of the ice sheets. It
Matt helps me to home in on any
found some space dust. Matt is 95 per cent
was I looking on the roof of Sidmouth’s
particles: we are looking for material with
I am still looking forward one day to
high density and a regular spherical shape.
getting out to Antarctica and looking for
Norman Lockyer Observatory instead?
meteorites there, but to have found space
We see a few objects that fit the bill and
Well it turns out that although you get
better contrast searching for meteorites in
dust just by looking on a roof in the UK,
zoom in, increasing the magnification
the snowy expanses, micrometeorites or
to me, seems quite amazing.
from 40 times to 5,000 times.
space dust falls everywhere. So looking for
At this level of magnification we can
Maggie Aderin-Pocock co-presents The
it on a large, flat undisturbed roof is
see spherical bead-like structures with a
Sky at Night and CBeebies Stargazing
actually a good place to start – though it
tapered cone at one end. This fits the
skyatnightmagazine.com 2017