[Music throughout] The solar system is full of rocks,
but not all of them are large.
Dust-size particles shed from comets
and asteroids, and smaller than a single grain of sand, traverse the
solar system at speeds reaching 40,000 miles an hour.
Our best knowledge of these tiniest meteoroids comes from measurements made near Earth.
But a clever use of data from the LISA Pathfinder mission has
tallied these particles nearly a million miles away.
Launched in 2015 and retired in 2017, LISA
Pathfinder is an ESA-led mission that demonstrated the technology needed
to built a future space-based gravitational wave observatory – a tool
for detecting ripples in space-time produced by, among other
things, merging black holes.
LISA Pathfinder was a resounding success, demonstrating it could keep its
instruments steadier than any mission previously flown.
It reduced unwanted forces on its instruments to less than a millionth of a billionth
of the gravity felt on Earth. To do this,
LISA Pathfinder had to isolate its instruments from environmental disturbances,
including occasional micrometeoroid impacts.
Each strike moved the spacecraft slightly, and it reacted immediately
by firing small thrusters. The science team found
and characterized 54 impacts over the mission’s duration, shown
here as yellow dots. LISA Pathfinder
did its work while orbiting Earth-Sun L1, a gravitational
balance point about a million miles toward the Sun. This is
essentially unexplored territory for understanding the solar system’s dust distribution.
The science team was able to use data in between
various other tests to search for dust impacts on the spacecraft,
seen here as purple regions.
The findings were broadly consistent with existing ideas of what generates
micrometeoroids found near Earth. These models predominantly favor nearby
Jupiter-family comets – like 9P/Tempel 1,
103P/Hartley, and 67P/Churyumov-Gerasimenko –
as the main dust makers, with additional contributions
from comets with longer periods, like Halley’s Comet.
Improving our dust knowledge will help future missions assess
potential hazards for spacecraft operating in the inner solar system.
It will also help us better understand the dust environments around other stars,
which can complicate searching for planets around them. And the same
technique can be used on other precision-measurement missions.
We’ll learn a bit more about the solar system each time one of these spacecraft is
struck by a microscopic crumb.
[Additional animations courtesy of ESA, Max Planck Institute for Gravitational Physics and Milde Marketing]
[Explore: solar system & beyond]
[NASA]