Two views of the Hiawatha crater region:
one covered by the Greenland Ice Sheet,
the other showing the topography of
the rock beneath the ice sheet,
including the crater.
Credits: NASA/Cindy Starr
An International Team and NASA make unexpected Discovery under
An international team of researchers, including a NASA glaciologist,
has discovered a large
meteorite impact crater hiding beneath more
than a half-mile of ice in northwest Greenland.
The crater - the first of
any size found under the Greenland ice sheet - is one of the 25
largest impact craters on Earth, measuring roughly 1,000 feet deep
and more than 19 miles in diameter, an area slightly larger than
that inside Washington's Capital Beltway.
The group, led by researchers from the University of Copenhagen's
Centre for GeoGenetics at the Natural History Museum of Denmark
worked for the past three years to verify their discovery, which
they initially made in 2015 using NASA data.
Their finding (A
Large Impact Crater beneath Hiawatha Glacier in northwest Greenland) is
published in the Nov. 14 issue of the journal Science Advances.
"NASA makes the data
it collects freely available to scientists and the public all
around the world," said Joe MacGregor, a NASA glaciologist at
Goddard Space Flight Center in Greenbelt, Maryland, who became
involved in the investigation in its early stages.
"That set the stage
for our Danish colleagues', 'Eureka' moment."
international team of scientists
together to unravel the mystery
Greenland's Hiawatha crater.
This video shows
that discovery came together.
Credits: NASA/Jefferson Beck
The researchers first spotted the crater in July 2015, while they
were inspecting a new map of the topography beneath Greenland's ice
sheet that used ice-penetrating radar data primarily from NASA's
Operation IceBridge - a multi-year airborne mission to track changes
in polar ice - and earlier NASA airborne missions in Greenland.
The scientists noticed an
enormous, previously unexamined circular depression under
Glacier, sitting at the very edge of the ice sheet in northwestern
Using satellite imagery from the Moderate Resolution Imaging
Spectroradiometer instrument on NASA's
satellites, Joe MacGregor also examined the surface of the
ice in the Hiawatha Glacier region and quickly found evidence of a
circular pattern on the ice surface that matched the one observed in
the bed topography map.
To confirm their suspicions, in May 2016 the team sent a research
plane from Germany's Alfred Wegener Institute to fly over the
Hiawatha Glacier and map the crater and the overlying ice with a
state-of-the-art ice-penetrating radar provided by the University of
MacGregor, who is an
expert in radar measurements of ice, helped design the airborne
Radar data from an intensive aerial survey
Hiawatha crater in May 2016
shown here in aqua-colored curtains.
arrow points to
central peak of the crater.
Credits: NASA/Cindy Starr
measurements of Hiawatha Glacier were part of a long-term NASA
effort to map Greenland's changing ice cover," MacGregor said.
"What we really
needed to test our hypothesis was a dense and focused radar
The survey exceeded
all expectations and imaged the depression in stunning detail: a
distinctly circular rim, central uplift, disturbed and
undisturbed ice layering, and basal debris - it's all there."
The crater formed less
than 3 million years ago, according to the study, when an iron
meteorite more than half a mile wide smashed into northwest
The resulting depression
was subsequently covered by ice.
"The crater is
exceptionally well-preserved and that is surprising because
glacier ice is an incredibly efficient erosive agent that would
have quickly removed traces of the impact," said Kurt KjŠr, a
professor at the Center for GeoGenetics at the Natural History
Museum of Denmark and lead author of the study.
The Hiawatha impact crater is covered by the Greenland Ice Sheet,
which flows just beyond the crater rim, forming a semi-circular
Part of this edge (top of photo) and a tongue of ice
breaches the crater's rim are shown in this photo
taken during a NASA Operation IceBridge flight on April 17.
Credits: NASA/John Sonntag
Kurt KjŠr said that the crater's condition indicates the
impact might even have occurred
toward the end of the last ice age,
which would place the resulting crater among the youngest on the
In the summers of 2016 and 2017, the research team returned to the
Hiawatha Glacier to map tectonic structures in the rock near the
foot of the glacier and collect samples of sediments washed out from
the depression through a melt-water channel.
"Some of the quartz
sand coming from the crater had planar deformation features
indicative of a violent impact.
This is conclusive
evidence that the depression beneath the Hiawatha Glacier is a
meteorite crater," said associate professor Nicolaj Larsen of
Aarhus University in Denmark, one of the authors of the study.
Earlier studies have
shown large impacts can profoundly affect
Earth's climate, with
major consequences for life on Earth at the time.
The researchers plan to
continue their work in this area, addressing remaining questions on
when and how the meteorite impact at Hiawatha Glacier affected the