A24 EZ RE THE WASHINGTON POST.SUNDAY, MAY 15 , 2022
BY MATTHEW CAPPUCCIThe first total lunar eclipse of
2022 is about to dye the moon
red on Sunday night. This
w eekend’s full “Flower Moon”
will be bathed in a rusty bronze
light as Earth’s shadow sweeps
across it, creating a spectacle
visible across most of North
America.
Just about everyone in the
contiguous United States will get
to enjoy the show, weather per-
mitting.
For those in California and the
Pacific Northwest, only the sec-
ond half of the eclipse will be
visible as the burgundy moon
rises during totality.
It’s the first of two total lunar
eclipses visible from the United
States this year.
The next is slated for the night
of Nov. 7, and will favor parts of
northwestern North America
missing out on Sunday night’s
show.What is a total lunar eclipse?
Eclipses of all forms occur
when one object blocks another.
In the case of a total lunar
eclipse, the Earth intercedes be-
tween the sun and the moon. You
might expect that to prevent
sunlight from reaching the
moon, making it disappear, but
that doesn’t happen. Instead,
some sunlight skims around the
periphery of Earth through our
atmosphere and is scattered
toward the moon.
For this to happen, the sun,
Earth and moon all have to be in
a line. That only happens duringa full moon.
Total solar eclipses, on the
other hand, take place during
new moons, when the moon slips
between Earth and the sun. That
extinguishes sunlight from
reaching a narrow corridor of
Earth, transforming day to night.
Solar eclipses also allow the
emergence of the sun’s milky
white corona, or atmosphere,
ordinarily outshone by blazing
sunlight.
Solar and lunar eclipses come
in pairs about two weeks apart;
the most recent partial solar
eclipse, on April 30, was visible
from South America.What will I see?
The total lunar eclipse will
begin as an unremarkable “pen-
umbral” lunar eclipse — a subtledarkening hardly perceptible to
the untrained observer. That’s
when the broadest, most diffuse
part of the Earth’s shadows be-
gins sweeping across the lunar
surface from the bottom left to
top right.
The partial phase of the
eclipse will ensue, when the edge
of the umbra, or darkest part of
the Earth’s shadow, first makes
contact with the moon.
You’ll see a veil of darkness
traverse the moon, its edge a
gentle curve representing the
shape of Earth. The shadow’s
curve will be more gentle than
that of the moon, since the Earth
is larger.
Once the shadow fully swal-
lows it, the moon will turn red.
That’s because the only light
reaching the moon is what
streams through Earth’s atmos-
phere.
Shorter wavelengths/higher
frequencies of light are scattered
away, leaving only the longer
wavelengths, colored red, able to
penetrate through the length of
the atmosphere at a low angle of
incidence. It’s the same premise
that makes sunrises and sunsets
red. Therefore, you’re seeing the
light of ever simultaneous sun-
rise and sunset projected ontothe moon.
Maximum eclipse comes when
the moon is most firmly bur-
rowed within Earth’s shadow,
immersed in nothing but eerie
red light. The color of a lunar
eclipse actually varies depending
on how polluted the atmosphere
is; astronomers rate the tonal
hues on the Danjon Scale, for
which a zero corresponds to a
hardly visible eclipse and a four
represents a coppery-rust one.
Volcanic eruptions and the pres-
ence of aerosols have been
known to reduce the vibrancy of
lunar eclipses.Timing
All times provided are in East-
ern time:
Begin penumbral eclipse:
9:32:05 p.m. Eastern time
Begin partial eclipse:
10:27:52 p.m. Eastern time
Begin totality: 11:29:03 p.m.
Eastern time
Maximum eclipse: 12:11:28
a.m. Eastern time
End totality: 12:53:55 a.m.
Eastern time
End partial eclipse: 1:55:07
a.m. Eastern time
End penumbral eclipse:
2:50:49 a.m. Eastern time
Note: For some on the WestCoast, the moon won’t rise until
totality is already underway.
Moonrise in San Francisco, for
example, is slated for 8:06 p.m.
Pacific time, just 23 minutes
before totality commences.How special are total lunar
eclipses?
Lunar eclipses aren’t nearly as
special as total solar eclipses.
Lunar eclipses can be visible
from the entire night side of
Earth, since the moon is visible
from anywhere. Most places get
one or two total lunar eclipses
per year.
Total solar eclipses, on the
other hand, are visible from a
given location only once every
375 years on average. The path of
totality may be a sliver hardly a
mile wide, and the experience is
surreal. The next that will be
seen in the United States will be
on Monday, April 8, 2024.The weather forecast
Patches of clouds will be scat-
tered intermittently across the
Eastern Seaboard, Intermoun-
tain West, Sierra Nevada and
Pacific Northwest. The center of
the country will see large expans-
es of clear skies favorable for
viewing.A total lunar eclipse tonight, visible to most of U.S., will turn the moon red
BY CHRISTIAN DAVENPORTIf it flew, and that was very
much a big if , the little helicopter
would take to the skies on Mars
five times — max — over a period
of 31 days.
But over the past year, the
plucky little helicopter known as
Ingenuity has taken to the Mar-
tian skies 28 times, far exceeding
expectations and giving scien-
tists a new vantage point on the
Red Planet. Over the past 13
months, it has stayed aloft in
total for nearly an hour, traveling
nearly 4.3 miles, with a max
speed of 12.3 mph and reaching a
top altitude of 39 feet.
It’s traversed craters, taken
photos of regions that would be
hard to reach on the ground, and
served as a surprisingly resilient
scout that has adapted to the
changing Martian atmosphere
and survived its harsh dust
storms and frigid nights.
Now the engineers and scien-
tists at NASA’s Jet Propulsion
Laboratory are worried that their
four-pound, solar-powered drone
on Mars may be nearing the end
of its life.
Winter is setting in on Mars.
The dust is kicking up, coating
Ingenuity’s solar panels and pre-
venting it from fully charging its
six lithium-ion batteries. This
month, for the first time since it
landed on Mars more than a year
ago, Ingenuity missed a planned
communications session with
Perseverance, the Mars rover that
it relies on to send data and
receive commands from Earth.
Will a dust-coated Ingenuity
survive a Martian winter where
temperatures routinely plunge
below minus-100 degrees Fahr-
enheit? And if it doesn’t, how
should the world remember the
little helicopter that cost $80
million to develop and more than
five years to design and build?
Those closest to the project say
that as time winds down for
Ingenuity, it’s hard to overstate
its achievements.
“The helicopter has just far
exceeded those initial expecta-
tions,” Lori Glaze, the director of
NASA’s planetary science divi-
sion, told The Washington Post.
Given the thinness of the Mar-
tian atmosphere, the scientists
and engineers who worked on
the Ingenuity weren’t sure the
experiment would succeed at all.
Thomas Zurbuchen, the head of
NASA’s science mission director-
ate, said at the time it was an
endeavor that forced NASA to
find the “right line between crazy
and innovative.”
So when the first flight, on
April 19, 2021, was a success,
NASA heralded it as a Wright
Brothers moment. And as a trib-
ute, Ingenuity had a postage-size
bit of fabric from the brothers’
aircraft, known as the Flyer, at-
tached to a cable under the solar
panel.
Ingenuity flew to Mars teth-
ered to the underbelly of the
Perseverance Rover, the star of
NASA’s most recent Mars mis-
sion. After traveling some 300
million miles over seven months,
Perseverance touched down in a
dramatic landing in February
2021 under a parachute with a
secret code snuck inside that
read, “Dare Mighty Things.”The rover, the size of an SUV,
landed at an area of Mars known
as Jezero crater, which once held
water and could yield clues to the
history of the planet and whether
life existed there. The rover is
gathering rocks and soil samples
that NASA hopes will be returned
to Earth in a future mission, as
well as using its seven instru-
ments to conduct science experi-
ments and test new technologies.
Ingenuity was something of an
add-on, a technology demonstra-
tion that could prove useful for
future missions and allow the
space agency’s scientists to ex-
plore more of the Martian land-
scape than they could by land
alone.
But flying an autonomous
drone on Mars would be extreme-
ly difficult. The atmosphere there
is just 1 percent the density of
Earth’s, so to generate lift, the
helicopter’s four-feet-wide
blades would have to spin incred-
ibly fast — 2,500 rotations per
minute.
“We built it as an experiment,”
Glaze said. “So it didn’t necessari-
ly have the flight-qualified parts
that we use on the big missions
like Perseverance.” Some, such as
components from smartphones,
were even bought off-the-shelf,
so “there were chances that they
might not perform in the envi-
ronment as we expected. And so
there was a risk that it wasn’tgoing to work.”
As Ingenuity kept flying, con-
trollers on the ground started to
realize their little project could
accomplish big things. Before its
fifth flight, they wrote in a blog
post that “our helicopter is even
more robust than we had hoped.
The power system that we fretted
over for years is providing more
than enough energy to keep our
heaters going at night and to fly
during the day. The off-the-shelf
components for our guidance
and navigation systems are also
doing great, as is our rotor sys-
tem. You name it, and it’s doing
just fine or better.”
As it continued to perform, the
scientists at NASA became in-
creasingly intrigued by the idea
that maybe this helicopter could
become an integral part of the
mission.
“What happened was, and this
is really key, after Ingenuity per-
formed so well on those first five
flights, the science team from
Perseverance came to us and
said, ‘You know what, we want
this helicopter to keep operating
to help us in our exploration and
achieving our science goals,’ ”
Glaze said.
So NASA decided to keep fly-
ing.
On its sixth flight, Ingenuity
ran into trouble. The helicopter
navigates with a camera that
takes 30 pictures a second of the
terrain below, each with a time-
stamp. An algorithm predicts
what the camera should have
seen at that particular moment
based on images taken moments
before. Then it calculates the
difference between the predicted
location and the actual location
of features of the ground to
correct its position, velocity and
altitude.
But on this flight the time-
stamps were off. As a result,
Ingenuity looked like it was being
flown by a drunk driver, “adjust-
ing its velocity and tilting back
and forth in an oscillating pat-
tern,” NASA said in the blog.
Still, it was able to land safely
within 16 feet of its target be-
cause of “the considerable effort
that has gone into ensuring thatthe helicopter’s flight control sys-
tem has ample ‘stability margin,’
” NASA wrote. In other words: “In
a very real sense, Ingenuity mus-
cled through the situation.”
Flight 9, in July, was also a
“nail biter,” as NASA wrote. Not
just because Ingenuity broke rec-
ords for flight duration and
cruise speed, but because it flew
over a crater, “an area called
‘Séítah’ that would be difficult to
traverse with a ground vehicle
like the Perseverance rover,”
NASA wrote in its blog.
Because Ingenuity was de-
signed as an experimental tech-
nology demonstration, engineers
designed it to fly over largely flat
terrain, more easily navigated by
its onboard camera. For this
flight, however, Ingenuity would
have to dip into the crater. That
required it to reduce its speed
and for engineers to tweak the
navigation algorithm. The flight
was a success, and Ingenuity was
able to beam back colored photos
of the region, including a location
that some think “may record
some of the deepest water envi-
ronments in old Lake Jezero,”
NASA wrote. “Given the tight
mission schedule, it’s possible
that they will not be able to visit
these rocks with the rover, so
Ingenuity may offer the only
opportunity to study these depos-
its in any detail.”
Since then, Ingenuity has sol-
diered on, overcoming obstacle
after obstacle. At one point in
September it detected an engine
problem during its preflight
checkout “and did exactly what it
was supposed to do: It canceled
the flight.”
About a month later, the prob-
lem was fixed, and it returned to
flight.
In April, it made another dis-
covery — flying over the para-
chute that slowed the rover for its
Mars landing, it spotted the ruins
of the shell that had protected the
rover as it plunged toward the
Martian surface. There was a pair
of human-made objects, sitting
on another planet, images that
“just blew my mind,” Glaze said.
In the past, NASA has been able
to spot vehicles on the surface ofMars through an orbiting space-
craft far away. But here were
pieces of hardware, close-up, in
such high-definition that the
“Dare Mighty Things” encoded
into the chute was visible
through a thin coating of red
Martian dust.
Then, 10 days later, on April 29,
it took its last flight to date,
Number 28, a quarter-of-a-mile
jaunt that lasted 2½ minutes.
Now NASA wonders if that will
be the last one.
The space agency thinks the
helicopter’s inability to fully
charge its batteries caused the
helicopter to enter a low-power
state. When it went dormant, the
helicopter’s onboard clock reset,
the way household clocks do after
a power outage. So the next day,
as the sun rose and began to
charge the batteries, the helicop-
ter was out of sync with the rover:
“Essentially, when Ingenuity
thought it was time to contact
Perseverance, the rover’s base
station wasn’t listening,” NASA
wrote.
Then NASA did something ex-
traordinary: Mission controllers
commanded Perseverance to
spend almost all of May 5 listen-
ing for the helicopter.
Finally, little Ingenuity phoned
home.
The radio link, NASA said,
“was stable,” the helicopter was
healthy, and the battery was
charging at 41 percent.
But, as NASA warned, “one
radio communications session
does not mean Ingenuity is out of
the woods. The increased (light-
reducing) dust in the air means
charging the helicopter’s batter-
ies to a level that would allow
important components (like the
clock and heaters) to remain
energized through the night pre-
sents a significant challenge.”
Maybe Ingenuity will fly again.
Maybe not.
“At this point, I can’t tell you
what’s going to happen next,”
Glaze said. “We’re still working
on trying to find a way to fly it
again. But Perseverance is the
primary mission, so that we need
to start setting our expectations
appropriately.”NASA’s little drone that could is still flying Martian skies
NASA/ASSOCIATED PRESS
Ingenuity hovers above the Mars surface o n April 22, 2 021.
Expected to fly at most five times, it has made 28 trips so far.But after exceeding
expectations, winter may
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