Sky & Telescope - July 2024 - 21

SAMPLING INSTRUMENT: NASA / ERIKA BLUMENFELD & JOSEPH AEBERSOLD;
APOLLO SAMPLE CHAMBER: NASA / JSC
The science gained from sample-return missions has turned remote dots of light into real worlds.
I
remember my first look at the solar system as a kid. As
a child of the early 1970s, I dove into books that often
showed off blurry images of the major planets taken by
professional observatories, ones that astrophotographers
could easily top today. Finally, a short paragraph would mention
the asteroids, perhaps with a photo of a dot in a star
field, and a " ? " on a table next to mass, rotation, etc.
Fast forward to today, and these places have become real
worlds: locales of rock, mud, and rubble that we can actually
discuss in terms of their geology and chemistry - often on a
microscopic level.
A pivotal development that enabled this sea change has
been sample-return missions: the intentional retrieval of
material from planets, asteroids, comets, and the space
between them.
For sure, we've long had samples come to us accidentally
in the form of meteorites, and to date, we've identified specimens
from the Moon, Mars, and the dwarf planet 4 Vesta.
We've even found interstellar dust samples linked to ancient
supernovae, preserved in recent snowfalls in Antarctica. But
these incidental samples are contaminated the moment they
hit Earth's atmosphere.
So scientists send out spacecraft (and sometimes astronauts)
to retrieve pristine material and bring it back to Earth
for study. By doing so, they deepen our understanding of the
science and formation of the solar system.
ALIEN RUBBLE A look inside the head of the OSIRIS-REX sampling
instrument, with the lid removed and the asteroid material revealed. The
largest rocks are about 1 cm (0.4 inch) wide.
A Brief History of Sample-Return Efforts
The dream of returning pristine samples from distant worlds
to the laboratory for study goes back to the early Space Age.
The very first samples collected were the contingency samples
scooped up by astronaut Neil Armstrong immediately after
setting foot on the lunar surface. This was an assurance that,
had Apollo 11 needed to leave the lunar surface quickly, at
least some lunar samples would still make it back to Earth.
Ultimately, the Apollo program would bring back 382 kilograms
(842 pounds) of lunar samples, over the span of six
missions. Apollo 11 collected mainly basalts and breccias, but
it was the unique composition of the fragments of ancient
lunar highland crust that led scientists to conclude that the
Moon had once been a magma ocean (S&T: July 2019, p. 14).
The Soviet Union completed the first robotic sample
return, when Luna 16 retrieved 101 grams (3.56 ounces) of
lunar soil and brought it to Earth on September 24, 1970.
Over three missions, Russia returned a total of 300 grams
of lunar samples. These were initially curated at the Russian
Academy of Sciences' Vernadsky Institute in Moscow, with
small samples eventually distributed to international partners.
Small amounts were even exchanged between the U.S.
and the Soviet Union.
But later sampling attempts met with failure. One ill-fated
try was Russia's Phobos-Grunt mission, launched in late
2011, which failed to leave Earth orbit. In fact, Russia has
yet to field a successful lunar or interplanetary mission since
the breakup of the Soviet Union. Its most recent attempt,
Luna 25, succumbed to " litho-braking " in 2023 when (in the
APOLLO ERA Researchers carefully handle a Core Sample Vacuum Container from the Apollo era at NASA ARES.
sk yand tele scope .o r g * JULY 2024 21

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Sky & Telescope - July 2024

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