This episode of SciShow Space is sponsored by BetterHelp.
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Some space missions get a lot of attention
Sputnik, the moon landing, Curiosity
but not all the biggest space exploration
stories get the attention they deserve.
In the mid-1980s, the European Space Agency, or ESA,
sent a robotic craft to fly by Halley’s
comet and capture the first-ever glimpse of a comet’s icy core.
And this arguably paved the way for all major missions
to study comets in the future --
including Rosetta.
This is the story of the Giotto comet mission.
Comets, those chunks of rock and ice hurtling
through space, have long fascinated humans.
Their conspicuous tails of water and dust
spark renewed interest whenever they
grace the night sky.
One such dirty space snowball that makes the rounds
pretty regularly is Halley’s comet,
which passes within sight of Earth every 76 years,
give or take a bit.
Its most recent visit was in 1986.
Since astronomer Edmund Halley worked out
that the comet would come back on the regular,
astronomers have eagerly awaited it as
an opportunity for study every time.
And in 1986, humans finally had the technology to
actually go there.
We now understand that comets are remnants
from the solar system’s formation,
making them helpful for understanding
how our little corner of space came to be.
And so came the Giotto mission, named for
the Italian painter Giotto di Bondone of the
Late Middle Ages, on account of his
representing the Star of Bethlehem as a comet in his painting,
Adoration of the Magi.
It is believed that he was inspired
specifically by the 1301 visit of Halley’s comet
so naturally the ESA chose to name
a space probe after him.
The mission was originally intended as
a joint effort along with NASA, but budget cuts
forced the U.S. to back out.
The ESA decided to push forward anyway,
greenlighting the project in 1980,
with its launch scheduled
for 1985.
Without the assistance of their U.S. counterparts,
the pressure was on: Halley’s comet was coming,
ready or not, and would not return again until 2061.
Not an ideal deadline for building a spacecraft.
The probe itself was relatively small,
with its experiments housed in a cylinder
less than two meters by one meter.
Inside was equipment for photographing the comet,
as well as several spectrometers for
analyzing its composition,
and an array of sensors for detecting
the comet’s halo of dust.
That very dust would prove a major challenge.
The scientific equipment onboard needed to survive
Giotto and the comet moving toward
one another at a combined speed of over
240,000 kilometers per hour.
At that speed, those dust particles would punch through even heavy metal shielding.
And Giotto needed to travel into the dust to photograph the comet’s icy nucleus.
Rather than weigh the craft down with super thick metal plating, the team instead shielded
it with one layer of aluminum and one layer of kevlar spaced a few centimeters apart.
Together, the layers could theoretically stop particles as big as 1 gram.
Once Giotto was completed, it was launched on July 2nd, 1985.
Giotto orbited the Earth three times, and then fired its thrusters to head off on its
eight-month journey to intercept Halley’s comet.
On March 12th, 1986, its sensors began picking up signs of hydrogen ions being ejected from
the comet.
It was getting close.
A day later, it entered the densest part of the comet’s tail.
That’s when the photos started coming in.
For the first time, scientists were seeing real images of a comet’s nucleus up close.
Over the next two hours, Giotto experienced thousands of dust collisions as it made its
way to within 596 kilometers of Halley’s comet.
But about 8 seconds before the craft reached its closest pass, the big one hit -- a one-gram
particle of dust.
ESA scientists lost contact.
It seemed that the probe was lost.
But over the next half hour, the craft continued sending back spurts of data and images.
Giotto had survived, stabilized itself, and re-established contact with Earth.
It would record its final dust impact 49 minutes after its closest approach, bidding farewell
to Halley’s comet.
The craft was injured, but intact.
The mission was a success.
lIt was so successful, in fact, and so not-yet-out-of-fuel, that after a return pass by Earth for a gravity
assist, Giotto was sent off to study a second comet in 1992.
The Giotto mission provided groundbreaking new data for scientists eager to learn about
comets and the early conditions of our solar system.
In addition to providing the first observations and the first photos of a comet nucleus, it
was Europe’s first deep-space mission and the first craft to use Earth’s gravity
to re-direct itself in space.
Giotto provided data that informed subsequent comet missions, including Rosetta — you
know, that mission where /put a lander on a comet/.
Giotto may not be as memorable as other headline-grabbers, but it was a little probe that could.
And it laid the groundwork for amazing science still to come.
This episode of SciShow Space was sponsored by BetterHelp.
BetterHelp is an online counseling resource, available worldwide, featuring therapists
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BetterHelp isn’t a crisis line.
If you are in an emergency situation, there’s a resource for you in the description.
Monthly subscriptions to BetterHelp are available, with financial aid for those who qualify.
And if you’re not completely satisfied with your experience, BetterHelp offers full refunds.
Go to BetterHelp.com/space or click the link in the description to learn more.
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