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Anyone who has ever seen aircraft in formation
flying can enjoy staying perfectly synchronized in flight. In
sponsored by The exoplanet of NASA
Program of exploration (ExEP), jet propulsion engineers
Pasadena Laboratory, California, takes flight training to a new location
extreme.
Their work marks a milestone in a larger
program to test the feasibility of a technology called starshade. Although
starshades have never flown in space, they have the potential to allow
revolutionary observations of planets beyond our solar system including
images of planets as small as the Earth.
The artist's concept of this artist shows how technology can block starlight and reveal the presence of planets. The video also shows the deployment of a starry stars model built by NASA's Jet Propulsion Laboratory at the Astro Aerospace / Northroup Grumman facility in Santa Barbara in 2013.
Credit: NASA / JPL-Caltech
A future Starshade mission would involve two spaceships.
We would be a space telescope in search of planets orbiting the stars
of our solar system. The other spacecraft would fly approximately 25,000 miles (40,000 km)
kilometers) in front of him, carrying a large shadow flat. The shadow would be
unfolds like a blooming flower – complete with "petals" – and block
the light of a star, allowing the telescope to have a better overview of any orbit
planets. But it would only work if the two spacecraft were to remain, despite the
long distance between them, aligned within 3 feet (1 meter) of each other.
Plus, and starlight would flow around the umbrella in the telescope
see and submerge the weak exoplanets.
"The distances we are talking about for the starshade
the technologies are pretty hard to imagine, "said Michael Bottom, an engineer at JPL.
"If the starshade was reduced to the size of a drinking glass, the
telescope would be the size of a pencil eraser and they would be separated by about
60 miles [100 kilometers]. Now imagine that these two objects float freely in
space. They are both facing these little tugs and elbows of gravity and
from other forces, and on that distance, we try to keep them both precisely
aligned at about 2 millimeters. "
The researchers found thousands of exoplanets
without the use of a starshade, but in most cases the scientists have
discovered these worlds indirectly. the transit
method, for example, detects the presence of a planet during its passage
in front of his parent star and causes a temporary drop in the star
brightness. Scientists have only very rarely taken direct pictures of
exoplanets.
Blocking the light of the stars is the key to a more direct performance
imagery and possibly realization in depth
studies of planetary atmospheres or find clues on the surface
characteristics of rocky worlds. Such studies are likely to reveal signs of
life beyond the Earth for the first time.
Looking for shade
The idea of using a celestial star to study
Exoplanets were proposed in the 1960s, four decades before the Discovery
first exoplanets. And while the ability to point a single
spacecraft regularly to a distant object is not new, either, keeping two spacecraft
aligned with each other to a background object represents a different type
of challenge.
Researchers are working on Starshade technology from ExEP
The development, called S5, has been entrusted to NASA with the development of starshade
technology for future space telescope missions. The S5 team is
fill three technological gaps that would have to be filled before a
The starshade mission could be ready to go in the space.
The work done by Bottom and his JPL engineer colleague, Thibault
Flinois fills one of these gaps by confirming that engineers could
realistically produce a starshade mission that met these strict
"detection and control training" requirements. Their results are
described in S5 Milestone 4
report, available on ExEP
website.
Enter the training
The specifics of a particular starshade mission –
including the exact distance between the two spacecraft and the size of the
shadow – depends on the size of the telescope. The S5 Milestone 4 report
looked primarily at a range of separation between 12,500 to 25,000 miles
(20,000 to 40,000 kilometers), with a grade of 85 feet (26 meters) in diameter.
These settings would work for a mission the size of NASA wide-field infrared survey
Telescope (WFIRST), a telescope with
A 2.4-meter diameter primary mirror is expected to be launched in the mid-2020s.
WFIRST will carry another starlight block
the technology, called a coronagraph, which is inside the telescope and offers its
own unique strengths in the study of exoplanets. This technology demonstration
will be the first high contrast stellar coronograph to go into space, allowing WFIRST
to directly image giant exoplanets similar to Neptune and Jupiter.
Starshade and Coronagraph technologies operate separately, but
Bottom has tested a technique that allows WFIRST to detect when a
starshade drifting subtly out of alignment. A small amount of starlight would
inevitably bend around the stars' shadow and form a bright, dark pattern on the
in front of the telescope. The telescope would see the pattern using a student
camera, which can image the front of the telescope from the inside – similar to
to photograph a windshield from a car.
Previous surveys of starshade had examined this
Bottom has made it a reality by building a computer program that
could recognize when the bright, dark pattern was centered on the telescope
and when he had deviated. Bottom found that the technique works
extremely well as a way to detect the movement of starshade.
"We can feel a change in the position of the stars shading
up to an inch, even on those immense distances, "Bottom said.
But detecting the misalignment of the star is a daunting task.
quite different proposal to keep it really aligned. To this end,
Flinois and his colleagues have developed a set of algorithms that use information
provided by Bottom's program to determine when star thrusters should
fire to put it back into position. The algorithms were created to
stand alone, keep the star star aligned with the telescope for days.
Combined with Bottom's work, this shows that keeping the
two aligned spacecraft is achievable with the aid of automated sensors and an automated thruster
controls. In fact, the work of Bottom and Flinois show that engineers
could reasonably meet the alignment requirements of an even larger starshade
with a larger telescope), positioned up to 46,000 miles (74,000 km)
kilometers) from the telescope.
"With such an unusually wide range of scales at stake
here it can be very counter-intuitive that this is possible at the beginning
look, "said Flinois.
A starshade project has not yet been approved for the flight,
but one could potentially join WFIRST in space in the late 2020s. Meet on
The flight training requirement is just one step forward to demonstrate that the
the project is feasible.
"This is a good example of how space technology works for me
becomes more and more extraordinary by building on past successes, "
said Phil Willems, head of Starshade's technology development activities at NASA.
"We use flight training in space whenever a capsule is docked at the
International Space Station. But Michael and Thibault went well beyond
that, and shown a way to maintain training on scales larger than the Earth
himself. "
JPL manages ExEP for From NASA
Division of Astrophysics.
Media contact
Calla Cofield
Jet Propulsion Laboratory, Pasadena, California
626-808-2469
[email protected]
2019-108
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