NASA’s new space observatory, the James Webb Telescope, has several objectives in
mind for its trip into space.
It will not only be used to deepen our understanding of the Milky Way, but it will also peer at
faraway exoplanets and celestial bodies, and search for evidence of dark matter.
The James Webb Space Telescope is setting its eyes towards the Big Dipper.
Despite reaching its final orbit on January 24, the $10 billion spacecraft is still months
away from making its first official scientific observations, as it must cool down and undergo
weeks of calibration work to ensure the 18 segments of the primary mirror operate as
one.
After reaching the second Lagrange point (L2), an area of balance between the Earth’s and
the Sun’s gravitational forces, NASA revealed its first target.
The Webb Telescope will soon be focused on one exceptionally bright star known as HD
84406.
It's a sun-like star about 260 light-years away, located in the constellation Ursa Major,
which means “Big Bear” in Latin.
This constellation includes the Big Dipper, which is the tail of this fuzzy beast.
HD 84406 star has a visual magnitude of 6.9, which is too dim to see with the naked eye.
You’ll need a telescope or high-power binoculars to see the star.
Now that the Webb Telescope has arrived at its ultimate destination in space, the mission
crew is preparing it for observations.
According to NASA, a bright star, like HD 84406, serves as a helpful target for the
team to align the Webb’s honeycomb-shaped mirrors and begin capturing engineering data.
Although this star will be useful for this specific purpose, the observatory will not
study it once it begins its science missions.
Once the telescope comes into focus, the star will be too bright to study with Webb.
However, for the time being, it is the ideal target for researchers to begin the search
for photons, a search that will bring them to the furthest reaches of the universe.
Engineers will use each of the mirrors to take 18 different out-of-focus images of HD
84406, from which a computer will determine how each must be positioned to bring the telescope
into focus.
The engineers may adjust the direction of each mirror in the slightest of increments,
each one equal to a ten-thousandth of the width of a human hair.
According to astrophysicist Eric Mamajek, from NASA’s Jet Propulsion Laboratory, the
star in question is somewhat cooler but much larger and more luminous than the Sun.
It has a surface temperature of roughly 5,000 Kelvins (8,540 degrees Fahrenheit), compared
to the Sun’s 5,778 Kelvins (9,940 degrees Fahrenheit).
Data from the ESA Gaia telescope shows that it is around 4.4 times the size of the Sun
and 11 times more luminous, and it may be part of a binary pair.
If it is a binary system, then the smaller star is most likely a red dwarf, approximately
half the size of the Sun, with the main star roughly 3 billion years old, which is younger
than the Sun.
The first calibration target was announced when the Webb Telescope approached its final
orbit, and NASA confirmed that its large High-Gain Antenna had been turned on.
This High-Gain Antenna was required before the calibration could begin, as it allows
the telescope to relay photos and data back to Earth.
It can now downlink observations via the Deep Space Network’s Ka radio band, a channel
that provides a substantially higher data rate for astronomers to download science photos
and data that they can analyze.
One of the telescope’s objectives is surveying potentially habitable exoplanets and some
of the most distant and oldest objects in the observable cosmos.
Webb will allow for unprecedentedly detailed observations of alien worlds.
As a result, scientists will be able to understand the nature of their atmospheres, as well as
learn more about how atmospheres work in general.
All of this requires Webb to send data back to Earth so that astronomers may examine the
observations and determine what exactly the telescope has observed.