A NASA sounding rocket will observe a nearby star to learn how starlight affects the atmospheres of exoplanets, key information in the search for life in the cosmos .
Using an updated instrument first launched in 2019, the mission has a new target: Procyon A, the brightest star in the Canis Minor constellation.
SISTINE-2 (Suborbital Imaging Spectrograph for Transition region Irradiance from Nearby Exoplanet host stars), will have its first opportunity to launch from the White Sands Missile Range in New Mexico on November 8 .
Answer the question of whether life exists in other parts of the universeis riddled with technical challenges . We still can’t travel to planets around other stars, called exoplanets, to see for ourselves. Our telescopes are also not powerful enough to see their surfaces.
Instead, astronomers peer into an exoplanet’s atmosphere, searching it for traces of chemicals associated with life . Water, methane, oxygen, ozone, and other so-called biomarkers produce unique light patterns that telescopes can detect from afar. But to interpret them correctly, astronomers must look at the planet’s star.
“The interaction between the atmosphere of the planet and the ultraviolet light of the host star ddetermines which gases serve as the best biomarkers,” Kevin France, an astrophysicist at the University of Colorado Boulder and the mission’s principal investigator, said in a statement.
Some ultraviolet (UV) wavelengths , for example, can break down carbon dioxide, releasing a single oxygen atom to combine with others to form molecular oxygen (composed of two oxygen atoms) or ozone (composed of three) .Stars that shed enough light can create spurious biomarkers on their planets , sending astronomers to look in the wrong
places.The SISTINE team aims to avoid this dilemma by creating a guide to the wavelengths that each type of star emits.There are many different types of stars and we still don’t have a complete picture of their light output or how it varies over time . With a starlight catalog, scientists could estimate whether a detected biomarker is a potential sign of life or a false signal generated by disturbing starlight.
On its next flight, SISTINE-2 will observe Procyon A, about 11.5 light-years away . Procyon A is an F-type star, which is slightly larger, hotter, and brighter than our Sun. Although it has no known exoplanets, studying Procyon A can help us understand F-type stars and their exoplanets throughout the universe. .
“Knowing the ultraviolet spectra of these stars will help us find the most promising stellar-planet environments with future NASA observatories,” France said.
SISTINE-2 comprises a telescope and an instrument known as a spectrograph, which splits light into its separate colors.SISTINE-2 will focus on ultraviolet light from 100 to 160 nanometers, a range that includes wavelengths known to produce false-positive biomarkers. By combining their data with existing X-ray, extreme ultraviolet, and visible light observations from other F-type stars, the team hopes to assemble a reference spectrum that will help astronomers interpret biomarkers on exoplanets orbiting F-type stars.
SISTINE-2 is also testing hardware. Before their 2019 flight, the team applied an enhanced lithium fluoride optical coating to the instrument’s mirrors to improve their UV reflectivity. The results, some three years later, help assess whether this specialized coating may be suitable for larger, longer-duration space missions .
Five-minute mission
As with its 2019 flight, the instrument will launch on a sounding rocket, a small suborbital rocket that makes brief observations in space before falling back to Earth. Ascending to an estimated altitude of approximately 280 km to access ultraviolet light that would otherwise be absorbed by our atmosphere, SISTINE-2 will observe Procyon A for about five minutes . The instrument will then fall back to Earth, descending by parachute for recovery and restoration.
The team is hoping for a soft landing to help with a quick turnaround to be ready for its third launch in July 2022, from the Arnhem Space Center in Nhulunbuy, Australia. There, a refurbished SISTINE instrument will observe Alpha Centauri A and B, G- and K-type stars, respectively, similar to and slightly cooler than our Sun, and the closest stars to us.
This system is also home to Proxima Centauri, a cool red dwarf star orbited by the closest known exoplanet, Proxima B. These observations will add additional entries to the growing catalog of stars: small but critical steps in the search for life.
