In space astronomy, anything is possible until proven otherwise. For the James Webb Space Telescope, the next impossible goal is Earth-Two.
For the James Webb Space Telescope, which is nearing the final stages of commissioning its 17 science instruments. One instrument—specifically designed to capture images and spectra of different types of cosmic objects—has the potential to go beyond discovering where alien worlds might lurk.
The Canadian scientific instrument, called the Near-Infrared Imager and Slit Spectrograph (NIRISS), can… It detects Earth-Two signals just by looking at a viable candidate host star.
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Crucially, the NERIS instrument will brilliantly examine global phenomena in near-infrared light. “at wavelengths down to 5.0 microns,” Nathalie Ourelet of the University of Montreal said in a blog post on NASA’s website. “The NERIS team developed four instrument modes to collect different types of data that are well suited to different scientific goals and objectives.”
Orelet added in the post that NERIS’ SSOS mode will enable the James Webb Space Telescope to collect extremely accurate spectra “from one bright object every time.” “This mode is optimized for time series observations. These are ideal for studying a phenomenon that changes over an observation period that typically lasts hours. Such as an exoplanet passing in front of its host star.”
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“Using a technique called transient spectroscopy, the NERIS instrument can collect a spectrum of an exoplanet’s atmosphere. Which contains different markers that allow astronomers to determine its composition, temperature, potential signatures of habitability, and other important properties,” Aurelet explained in a post.
Then there’s WFS mode, which will enable NERIS to help the James Webb Space Telescope collect information from thousands of objects, “such as galaxies, at the same time across the detector’s entire field of view”, which amounts to 4.84 arcminutes, according to Aurelet. “The spectra of thousands of galaxies will enable their distances, ages, and other physical parameters to be measured to track how galaxies have evolved over the life of the universe.”
And there’s more. NERIS is able to collect information from many spectra at once in WFS mode, which means that separate spectra may overlap (if the light sources are too close to our point of view). “There are two orthogonal inclusions, GR150C and GR150R, that can produce horizontal and vertical spectra, respectively, which helps separate mixed spectra from different galaxies,” Aourillet said.
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In addition, Nerys Webb’s EMI mode will enable inspection of nearby cosmic objects (from our perspective, of course). This will be done using a special technique known as interferometry. “The mask inside the device allows light to pass through only certain parts of the primary mirror,” Aurelet explained. “Astronomers can increase a telescope’s resolution by a factor of about 2.5 by looking at the patterns created where carefully selected beams of light interfere with each other.”
Using this method, two objects in apparent proximity can still appear as two different points of light, rather than a meaningless blur. However, since the mask blocks too much light, the observed cosmic objects must be fairly bright for detection. But, given enough brightness, the EMI mode of the NERIS instrument will enable the James Webb Space Telescope to observe brown dwarfs, protoplanetary disks, and exoplanets themselves. It’s our first time using such a method to set our eyes on alien worlds. And it’s just a small portion of the wealth of scientific knowledge in store once Webb begins his science missions in earnest this summer.
