One of the rules for building a spaceship is to have as few moving parts as possible, says Andy Bunker, an Oxford University astrophysicist.
One of the four instruments on the James Webb Space Telescope is getting ready to open their eyes to the universe. He is one of seven European scientists that have shaped the design of NIRSpec, and is eagerly awaiting the moment when the instrument starts delivering data.
Bunker told Space.com that he has always been interested in pushing the limit for the most distant known object. It is about understanding the early stages of the universe. We are trying to chase this.
The scientific mysteries no other observatory could uncover is related to James Webb Space Telescope.
The oldest and most distant galaxies that emerged in the young universe from dust and gas after the Big Bang were studied by the giant mirror in the center of the room. It will be possible to see it by observing the heat-carrying part of the spectrum. The light from the earliest stars shifted into the part of the spectrum known as the redshift because they were so far away.
The rule-breaking quarter of a million microshutters of NIRSpec will give the capabilities a boost. The instrument flown on the Hubble Space Telescope is considered to be the predecessor of NIRSPec, which will be more than one hundred times better.
The instrument that will produce the most eye-catching images is not NIRSPec. The cameras will have to do that.
Hundreds and thousands of others will be given an unprecedented amount of information by NIRSpec.
NIRSpec doesn't take images. The light spectrum is divided into individual components. The spectrum reflects the light-absorbing properties of the objects and thus their chemical composition. Every chemical element in the body absorbs light in a certain way, which shows a line in the captured spectrum. Researchers can determine what chemical compounds are present by capturing an object's spectrum.
There is a lot of information in the spectrum. We can chart how chemical elements build up in the universe, but also determine the distance and properties of the universe, such as the rate at which they turn their gas into stars.
To take the fingerprints of these objects accurately, spectrographs need to block all other light from their field of view. Those on Hubble use a slit, a narrow opening in a metal plate, to target only the studied object.
Bunker said that the slit allows you to get as sensitive as you can. If you look at some of the deep fields where you have high densities of potentially interesting objects, it is very ineffective.
The telescope will have to stare at the objects for hundreds of hours to collect enough light to see them, and it's obvious that the approach isn't practical.
This is where NIRSPec has their microshutters. Astronomers will be able to observe and measure a hundred or more galaxies at the same time, thanks to the flexibility of the micro-shutters.
NIRSpec is the first spectrograph of its kind to be flown in space. The four rectangular sections of the array are arranged by the number of microshutters.
The back of the array has a magnet. The ground control teams determine which shutters open and which remain shut by applying an electrical current to every single microshutter. Engineers cannot open microshutters that are too close to each other because of the overlap of the observed objects. It's possible to study around a hundred objects at the same time.
Bunker said that a fraction of the microshutters will fail, but that they will still be able to use the others. Some may get stuck open, which would add some background light, but that would be very few.
Scientists will be able to answer big questions not about individual stars and galaxies, but the entire universe, thanks to the vast quantities of stars, galaxies, clusters, planets and other bodies that NIRSpec is going to look at.
The number of objects that we will be able to tackle will enable us to see how variables depend on each other. The rate at which stars are forming varies with the size of the galaxy.
With the help of NIRSpec, astronomer will be able to see the first stars and galaxies that formed in the universe, but also to know what they were made of and how, upon their death, they gave rise to other chemical elements that gradually populated the universe as we see it
Bunker said that they know that hydrogen and helium formed in the Big bang. The number and fraction of heavier elements should increase in the universe. We hope to measure that directly.
The telescope has been operating at minus 369.4 degrees Fahrenheit since January, when it was 930,000 miles away from Earth. The telescope's super sensitive detectors would be dazzled by any warmth emitted by the telescope itself.
The scientists will be able to test their performance in space for the first time because the four instruments are gradually opening their eyes.
Bunker said there were a number of activities for NIRSpec over the next three months. The telescope is performing very well.
The public will have to wait until early July to see the universe through the eyes of the most expensive space telescope ever built.
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