NASA is expected to launch two more sounding rockets from northern Australia in the first half of July. These missions will help astronomers understand how starlight influences a planet’s atmosphere, which can make or break its ability to support life as we know it.
" data-gt-translate-attributes="[{" attribute="">Nasa is set to launch two more sounding rockets from northern Australia in the first half of July, following a successful launch on June 26. These missions will help scientists understand how starlight influences a planet’s atmosphere, which can make or break its ability to support life as we know it.
Both missions will study Alpha Centauri A and B – two Sun-like stars near our own – using extreme and far ultraviolet light. Ultraviolet light, which has wavelengths shorter than the light visible to the human eye, is a crucial factor in the search for life. A small amount of ultraviolet light can help form the molecules necessary for life, but too much can erode an atmosphere, leaving behind a planet inhospitable to life as we know it.
“Ultraviolet radiation from the Sun has played a role in how " data-gt-translate-attributes="[{" attribute="">March lost its atmosphere and how " data-gt-translate-attributes="[{" attribute="">Venus turned into a dry, arid landscape,” said Brian Fleming, an astronomer at the University of Colorado, Boulder, and principal investigator for one of the missions, the Dual-Channel Extreme Ultraviolet Continuum Experiment, or DEUCE. “Understanding ultraviolet radiation is extremely important to understanding what makes a planet habitable.”
The closest star system to Earth is the famous Alpha Centauri group. At a distance of 4.3 light years, this system is made up of the binary formed by the stars Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf Alpha Centauri C, also known as Proxima Centauri. NASA’s Hubble Space Telescope gave us this stunning view of the bright Alpha Centauri A (left) and Alpha Centauri B (right). Credit: NASA/ESA/Hubble
Of more than 5,000 known exoplanets throughout the galaxy, only Earth is known to harbor life. In the search for other exoplanets that could host life as we know it, astronomers have focused on planets that orbit within the habitable zone – defined as the distances from a star where a planet’s surface temperature could withstand water.
“But that’s a crude way to characterize habitability,” Fleming said.
Although water helps make a planet hospitable, for a planet to support an Earth-like biosphere, it also needs an atmosphere. If the habitable zone is bathed in too much ultraviolet radiation, any water vapor from the upper atmosphere could escape, rapidly drying out the planet. Atmospheres can also be eroded by radiation and extreme flares from a planet’s host star, exposing the surface to strong ultraviolet radiation, which can shatter molecules like DNA.
But the amount of ultraviolet radiation emitted by different types of stars is poorly known. Without precise knowledge, astronomers cannot accurately predict which planets might harbor life.
“We need to understand the stars so that we can understand all the planets we find there,” said Kevin France, an astronomer at the University of Colorado, Boulder, and principal investigator of the suborbital imaging spectrograph for the region’s irradiance. transition from host stars to nearby exoplanets, or SISTINE, mission.
The Spectrograph for the Transition Region Irradiance of Nearby Exoplanet Host Stars, or SISTINE, is being prepared for launch. Credit: NASA Wallops
DEUCE and SISTINE will take these important measurements of ultraviolet light to help refine the search for habitable planets. Launched just a week apart, the two missions will work together to get a full picture of the ultraviolet light coming from Alpha Centauri A and B.
The researchers selected Alpha Centauri A and B because they can serve as useful benchmarks for calibrating observations of the Sun – the only other star for which we have full ultraviolet measurements. Ultraviolet light is absorbed by dust and gases in space. This makes it almost impossible to measure ultraviolet light from more distant stars at the level needed for these types of analyses. The Alpha Centauri system, however, is only 4.3 light-years away, close enough that much of its ultraviolet light will reach us before being absorbed.
Ultraviolet light is also mostly blocked by Earth’s atmosphere, so researchers have to send instruments into space to measure it. Since the full range of ultraviolet light cannot be measured with a single instrument, DEUCE will measure the shorter extreme ultraviolet wavelengths and SISTINE will measure the longer far ultraviolet wavelengths. The wavelength coverages will overlap slightly so that the collected data can be calibrated and used as a single data set. This information will then be used to create models that can help astronomers assess which other star systems might support habitable environments.
“Looking at Alpha Centauri will help us check if other stars like the Sun have the same radiation environment or if there is a range of environments,” France said. “We have to go to Australia to study it because we can’t easily see these stars from the northern hemisphere to measure them.”
SISTINE is set to launch on July 4 and DEUCE on July 12.
Both missions, aboard NASA’s Black Brant IX two-stage sounding rockets, will launch from Arnhem Space Center in eastern Arnhem Land, Australia’s Northern Territory. Arnhem Space Center is owned and operated by Equatorial Launch Australia, or ELA, on the land of the Yolngu, the traditional custodians and landowners.
With a third mission, the X-ray Quantum Calorimeter, or XQC, which flew on June 26, these scientific studies can only be conducted from the southern hemisphere.
