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NASA's Dawn mission is coming to an end
after 11 years of breakthrough in global science, bringing together
Breathtaking images, and perform unprecedented spaceship exploits
engineering.
Dawn's mission has been extended several times,
outperforming scientists' expectations in his exploration of two planets
bodies, Ceres and Vesta, which constitute 45% of the mass of the
Belt of asteroids. Now, the spacecraft is about to miss an essential fuel, hydrazine.
When that happens, probably between mid-September and mid-October, Dawn
loses its ability to communicate with the Earth. It will remain in silent orbit
around Ceres for decades.
"Although it's sad to see Dawn
departure from our mission family, we are extremely proud of its many
accomplishments, "said Lori Glaze, acting director of the Planetary Science Division at NASA headquarters in
Washington. "Not only did this spaceship unlock scientific secrets to
these two small but significant worlds, it was also the first spaceship to
visit and orbit bodies on two extraterrestrial destinations during his mission.
Dawn's scientific and technical achievements will resonate throughout history. "
NASA's Dawn spacecraft has made science fiction a scientific fact by using ion propulsion to explore the two largest bodies of the main asteroid belt, Vesta and Ceres. The mission will end this fall, when the spacecraft will run out of hydrazine, which will keep it oriented and in communication with the Earth.
When dawn is launched from Cape Canaveral Air
Force Station in Florida in September 2007, attached to a Delta II-Heavy
rocket, scientists and engineers had an idea of what Ceres and Vesta were looking at
as. Through terrestrial and space telescopes, including NASA's Hubble
The space telescope, the bodies in the asteroid belt between Mars and Jupiter were
visible – but even the best images were blurry.
From 2011 to 2012, Dawn swept Vesta,
capture images that have exceeded everyone's imagination – craters, canyons and
even mountains. Then on Ceres in 2015, Dawn showed us a cryovolcano and
mysterious bright spots, which scientists later discovered could be salt deposits
produced by the exposure of brackish liquid from the interior of Ceres. Through dawn
the eyes, these brilliant spots were particularly astonishing, brilliant as diamonds
scattered on the surface of the dwarf planet.
"The legacy of Dawn is that he has explored two of
the last unexplored worlds in the inner solar system, "said Marc Rayman of
NASA's Jet Propulsion Laboratory in Pasadena, California, which serves as Dawn's
Director of Mission and Chief Engineer. "Dawn showed us extraterrestrial worlds that
for two centuries there were only points of light in the middle of the stars. And he has
produces these intimate portraits richly detailed and revealed exotic,
Mysterious landscapes unlike anything we have ever seen. "
Engineering practices
Dawn is the only spacecraft to orbit a body in
the asteroid belt. And it's the only spacecraft to orbit two extraterrestrials
destinations. These feats were possible thanks to the ionic propulsion,
extremely effective propulsion system familiar to science fiction fans and
space lovers. Dawn pushed the
limitations of the system's capabilities and endurance, showing how useful it is
other missions aimed at visiting multiple destinations.
Driven by ionic propulsion, Dawn reaches Vesta
in 2011 and studied from surface to core for 14 months in orbit. In
In 2012, engineers maneuvered Dawn out of its orbit and guided it through the asteroid
belt for more than two years before inserting it into orbit around the dwarf
Planet Ceres, where it has been collecting data since 2015.
Window on the past
Meanwhile, scientists have gained new knowledge
in the early stages of our solar system, fulfilling Dawn's goal. the
mission was named for its purpose: to learn more about the dawn of solar
System. He targeted Ceres and Vesta because they work like time capsules,
intact survivors of the first part of our history. And the duo delivered,
give scientists an overview of the original building blocks of Solar
System.
"Vesta and Ceres each told their
story of how and where they formed and how they evolved – a fiery magmatic
the story that led to rocky Vesta and a colder, water-rich story that resulted
in the former oceanic world Ceres, "said Carol Raymond of JPL, principal
investigator of the Dawn mission. "These treasures of information
will continue to help us understand other bodies in the solar system far into
l & # 39; future. "
Ceres spectacular
There were so many things that scientists did not know
about Ceres before the arrival of Dawn. Raymond was wondering if they could find Ceres
covered with a smooth, young surface – a huge ball with a gel
crust. Instead, they found the dwarf planet carrying the chemistry of its former
ocean. "What we found was completely mind-boggling.The story of Ceres is just
whistled over its entire surface, "she said.
Some of the brilliant bright dots were revealed
to be shiny salty deposits, composed mainly of sodium carbonate
its path to the surface in a frothy brine from inside or below the crust.
The results reinforce the idea that dwarf
planets, not just frozen moons like Encelade and Europa, could have hosted oceans
in the course of their history – and potentially again. Analyzes from Dawn data
suggest that it can still be liquid under the surface of Ceres and that some regions
were relatively recently geologically active, feeding on a deep reservoir.
One of Dawn's biggest revelations about Ceres lies in
the region of Ernutet crater. Organic molecules have been found in abundance.
Organic materials are among the building blocks of life, even though Dawn's data can not
to determine if the organic compounds of Ceres were formed by biological processes.
"It is becoming increasingly clear that the
the organic matter at Ernutet came from within Ceres, in which case they could have
has existed for a while in the inner first ocean, "said Julie
Castillo-Rogez, Dawn Project Scientist and Senior Research Scientist at
JPL.
Vibrant Vesta
In Vesta, Dawn's investigation into the beginning of
Solar System found a witness 4.5 billion years old that he could interrogate. Dawn
mapped the planet's craters similar to the planet and revealed that its north
the hemisphere had more impact than expected, suggesting
were larger objects in the early asteroid belt than the scientists thought.
Vesta also had other surprises. While that is
technically classified as an asteroid, this label belies the rich and varied
Dawn's ground revealed, and processes similar to the planet that Vesta has known.
Hubble had now relayed images of a mountain in the center of a huge pool
called Rheasilvia. Dawn's mapping showed that she was twice the height of the mount.
Everest, and he revealed canyons that rival the size of the Grand Canyon. Dawn too
confirmed Vesta as a source of a very common meteorite family.
Now, towards the end of Dawn's second extension
mission to Ceres, the spacecraft continued to gather high resolution
images, gamma and neutron spectra, infrared spectra and gravity data.
Almost once a day, it will fly over Ceres about 35 kilometers from
its surface – only about three times the altitude of a passenger jet –
collect valuable data until it spends the last of the hydrazine that feeds
thrusters controlling its orientation. Dawn's reaction wheels failed earlier in the mission, leaving her heavily dependent on this vital fuel.
When dawn s exhaust in the next
months or two, the spaceship is going
loses its ability to communicate with the Earth, but it must not hit Ceres.
Because Ceres has conditions of interest for
scientists who study the chemistry that leads to the development of life, NASA
follows strict protocols of planetary protection for the elimination of dawn
spatialship. Unlike Cassini, who deliberately plunged into Saturn's atmosphere
to protect the system from contamination – Dawn will stay in orbit around
Ceres, which does not have atmosphere.
Engineers designed the final orbit of Dawn for
Make sure that it will not fail for at least 20 years – and probably more decades.
Rayman, who led the team that stole Dawn
throughout the mission and in its final orbit, likes to think of the end of Dawn
this way: as "a heavenly monument inert to human creativity and
ingenuity."
More about Dawn's mission
inheritance here: https://dawn.jpl.nasa.gov/mission/toolkit/
The Dawn mission is managed by JPL for the scientific mission of NAPrSA
Direction to Washington. Dawn is a management discovery project
Program, run by NASA's Marshall Space Flight Center in Huntsville, Alabama.
JPL is responsible for the overall science of the Dawn mission. Northrop Grumman at
Dulles, Virginia, designed and built the spaceship. German Aerospace
Center, Max Planck Institute for Solar System Research, Italian Space Agency
and the Italian National Institute of Astrophysics are international partners on the
mission team.
For a complete list of mission participants, visit:
https://dawn.jpl.nasa.gov/mission
More information on Dawn is available at the following sites:
Https://dawn.jpl.nasa.gov
News Media Contact
Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, California.
818-393-6215
[email protected]
Dwayne Brown / JoAnna Wendel
NASA Headquarters, Washington
202-358-1726 / 202-358-1003
[email protected] / [email protected]
2018-210
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