The James Webb Space Telescope taxed the scientific and engineering communities
before, during, and after its launch!
However, the 10 billion dollar gamble is beginning to
pay off as the space telescope has started showing us the stuff it is capable of with
the latest image of the cosmos that it sent back
to the earth!
In fact, even at this stage, the JWST is already sending back intriguing images,
and in this video, we will show you how NASA has rapidly got to this stage where
the JWST has captured an unknown object in space!
How far did you go in your riskiest adventure?
If you ask NASA, the answer is literally about 1 million miles!
And it was at the cost of a whopping 10 billion dollars!
Basically, everything about the JWST had to be invented
to tackle the unique problems it would face at its location.
And perplexingly, the inventions added to the complexity of the
telescope!
For instance, the engineers had to develop a way to cool the telescope to
ultra-low temperatures to enable it to work without interference.
The solution was a series of five sheets of special materials
acting as a heat shield.
But then, the five sheets had to be precisely placed for them
to work!
But that was not the only problem posed by this solution!
Each of the sheets is as large as a standard tennis court, which complicated
the launch since, obviously, there is no rocket in operation that could take the heat
shields!
The solution to the problem caused by the solution to the cooling problem was
to fold the sheets during launch and unfurl them during the trip to its permanent orbit!
That was a scary proposal as the JWST quickly left the range of distance within
which humans could approach it to fix any problem!
The reflecting mirror had to be handled the same way for the same reason; it just
couldn't fit onto any launch rocket!
The solution was to break it up into 18 different hexagonal mirrors and fold it up during the
launch to orbit!
Thankfully, the uncertainty of the launch is behind us, and the task at hand for NASA
is to align and calibrate the different components
so that they can all work together and as intended!
The good news is that even though the alignment process, which involved fine-tuning
the positions and inclinations of the 18 segments with nanometer-scale precision, is not
yet complete, the JWST mission is already producing images that take the scientists'
breath away!
But how is the alignment done?
It contains some mind-blowing engineering!
There are seven small motors fixed behind each of the
JWST's 18 slightly curved hexagonal mirrors.
Their function is to move and reshape the curvature of each segment so that all
18 can act as a single large mirror.
Six of these motors are grouped in pairs, equally distanced, and located around each
mirror segment.
These are used to move the mirror.
However, the seventh motor is at the center and is connected to the mirror's
six corners with struts.
This motor can adjust the tension of the struts, which optimizes
the curvature of that mirror segment.
The motors are so sensitive that they can precisely move the mirrors to within about
one-ten thousandth of the diameter of a human hair!
This precision to within a fraction of a wavelength of light is crucial for scientists
to obtain high-quality images from the JWST!
NASA scientists used a mathematical analysis called "phase retrieval" to study how the
movement of each individual segment changed the sharpness of the final image.
With this info, there were two crucial tasks to
complete before the segments could function as
a single, monolithic mirror: coarse alignment and fine alignment.
In coarse alignment, the mirror segments were moved up and down until they aligned to
form one giant mirror.
However, there were still minute alignment errors that needed to
be corrected to obtain the best possible image.
This is where the fine alignment occurs.
In this step, instead of moving the mirror segments, the small optics inside NIRCam
moved instead.
When the telescope is pointed at a star, the light from the star first hits the primary
mirror, in which the individual segments are now aligned reasonably well.
The light then continues its path through the secondary and
tertiary mirrors inside the telescope and enters the NIRCam instrument.
During the fine alignment, the optics inside NIRCam are
very carefully adjusted until the star is completely in focus.
The coarse and fine alignment steps are both repeated until the sharpest image can be
obtained.
The image released by NASA recently shows how a star looks when these
steps are completed.
Prior to this, NASA released a "stacked" image back in February.
For this, each of the individual mirror segments was fine-tuned to create 18 sharp
images of the star, but each from a slightly different vantage point.
The 18 images were then stacked to produce a single image
When the mirror alignment process started in early January, the ground team trained
the telescope on HD 84406, a star that the scientists described as very boring in our
Milky Way galaxy.
The star, 100 times fainter than what can be seen with the naked
eye, was chosen not for its scientific significance but purely for its brightness and
location.
The star is located about 2,000 light-years away.
At the beginning of the alignment process, the telescope was delivering 18 individual
images of the star, with each of the primary mirror segments acting as a telescope on its
own.
However, the image released recently shows a bright-shining amber-colored star
emanating streams of light across the universe.
Even more interesting than the star itself, however, is its background, revealing
dozens of specks and dots — each a distant galaxy that was previously out of reach!
These distant galaxies make Webb's first image a so-called deep field.
Such photographs, focusing on small sections of
the sky, aim to capture the most distant objects in the universe.
Deep fields are a specialty of the Hubble Space Telescope,
Webb's predecessor.
Webb, however, will handily beat Hubble in its ability to peer into
the depths!
Showing its superiority, where Hubble requires weeks to obtain some of its best deep
field images, the JWST will accomplish the same results within hours!
But of course, the two observatories don't image the universe
in the same wavelengths; Hubble is an expert at visible and ultraviolet radiation,
and JWST uses infrared.
The Webb telescope was designed to be up to 100 times more sensitive than Hubble,
and that goal has not just been accomplished but exceeded!
Lee Feinberg, Webb optical telescope element manager at the NASA Goddard Space
Flight Center, said in the last fall, NASA said it would know that the telescope is working
correctly when it has an image of a star that looks like, well, a star.
Now, the JWST has produced such an image!
He was excited that the optical performance of the telescope
was absolutely phenomenal!
The performance was as good if not better than NASA's
most optimistic prediction!
The mirror alignment was done with the help of the Near Infrared Camera, or NIRCam,
one of JWST's four scientific instruments.
The remaining three are still waiting to be activated.
They include the Near-Infrared Spectrograph, which will examine the light
spectra from distant objects to learn more about their physical properties, such as their
temperature and chemical composition; the Mid-Infrared Instrument, which is both a
camera and a spectrograph that captures images in wavelengths the eye can't see; and
the Near-Infrared Imager and Slitless Spectrograph, a very precise instrument that will
look for and investigate exoplanets.
The next stage will take about six weeks and will be followed by a final alignment stage
in which the JWST team will adjust any residual positioning errors in the mirror
segments.
The team is on track to conclude all aspects of Optical Telescope Element
alignment by early May, if not sooner, before moving on to approximately two months of
science instrument preparations.
Webb's first full-resolution imagery and science data
will be released in the summer.
In addition to aligning the mirror, the scientists had to wait for the instruments to cool
down to extremely cold temperatures close to absolute zero.
Since Webb is an infrared telescope, and infrared light is essentially
heat, any warmth emitted by the telescope and its instruments would dazzle the detectors
and make it impossible to see the most distant objects in the universe.
Many of the features also have redundancies built into them, which means if a system
should fail, there will be another way to achieve the same objective.
The JWST is a collaboration among NASA, the European Space Agency, and the
Canadian Space Agency.
It is named after former NASA Administrator James E. Webb,
who led the agency during the Mercury, Gemini, and much of the Apollo space
programs.
What will the JWST picture first when it is certified as ready?
Except you have the topmost clearance at NASA, you could only
guess, for now!
Jane Rigby, the James Webb Space Telescope operations project scientist
at NASA Goddard Space Flight Center in Maryland, said the targets had been
selected, but they remain a super-secret!
However, many other early targets for the observatory are public knowledge.
During a news conference, Rigby confirmed that JWST's
first year of science observations is already finalized.
She revealed NASA received more than a thousand research
proposals from astronomers worldwide and selected "the best ones," including those
looking for light from the first stars and galaxies that emerged in the universe only
a few hundred million years after the Big Bang.
Let's hear what you think of the early images of the universe captured by the JWST in
the comment section below!