NASA sounding rockets lift off to assess Alpha Centauri


Two sounding rockets are being launched from Australia this month, carrying experiments designed to measure whether ultraviolet light from stars in the Alpha Centauri system could be harmful to any potential life on the planets orbiting them. The research will also tell us how normal the sun is — or isn’t.

Alpha Centaurionly 4.3 light-years away, comprises two main stars, Alpha Centauri A and Alpha Centauri B (which form a binary pair), as well as a third star, Proxima Centauri. Although no planets have been positively identified orbiting Alpha Centauri A or B, if any exist, the ultraviolet light from their stars can have a strong bearing on whether or not they harbor life.

Just the right amount of ultraviolet light can break apart simple organic molecules, such as methane, prompting the molecular fragments to reform into more complex molecules needed for life. On the other hand, too much ultraviolet can break up water vapor, making it susceptible to being removed from a planet’s atmosphere by solar wind and leaving the planet dry and barren, like March it’s today.

Related: NASA to launch 3 sounding rockets from Northern Territory to boost Australian space efforts

“Understanding ultraviolet radiation is extremely important in understanding what makes a planet habitable“said Brian Fleming, an astrophysicist at the University of Colorado at Boulder, in a statement (opens in a new tab). Fleming is the principal investigator of one of the missions, the Dual-Channel Extreme Ultraviolet Continuum Experiment (DEUCE). The other experiment launched on a sounding rocket is called the Suborbital Imaging Spectrograph for Transition region Irradiance from Near Exoplanet host stars (SISTINE). The sounding rockets fly in a parabolic trajectory, spending perhaps 20 minutes in space before re-entering the atmosphere, meaning each experiment will have little time to make observations.

Sistine launched first, Wednesday July 6, from the Arnhem Space Center in the Australian Northern Territory. It was the second launch from the private commercial space center after June launch of NASA’s quantum x-ray calorimeter. If all goes well, DEUCE will take off on July 12. Each mission will take a suborbital trajectory on NASA’s Black Brant IX two-stage sounding rocket.

Missions must be launched from the Southern Hemisphere as the Alpha Centauri system is not visible above a latitude of 29 degrees north and just skirts the horizon from Florida, while high in the sky seen from Australia. SISTINE collects data at longer far-ultraviolet wavelengths while DEUCE complements this by looking at shorter extreme-ultraviolet wavelengths, with some overlap between the two experiments so that the data can be calibrated and used as a single data set.

The SISTINE experiment, ready to be loaded onto its sounding rocket. (Image credit: NASA Wallops)

Observing stars in the ultraviolet is difficult because the ozone layer in earth’s atmosphere blocks ultraviolet light, forcing scientists to send ultraviolet telescopes into space. Meanwhile, the interstellar medium of gas and dust between stars also absorbs ultraviolet light, so stars that are an appreciable distance away cannot be seen very clearly in ultraviolet light.

As such, we have complete ultraviolet observations for only one star, the Sun. But how typical are ultraviolet emissions from the sun? Astronomers don’t know; they need ultraviolet readings from other stars to figure this out. Alpha Centauri A and B make good targets for study, for two reasons. First, they are close, so their ultraviolet light is not attenuated by the interstellar medium. Second, they have masses and temperatures similar to those of the sun.

“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,” said Kevin France, an astrophysicist at the University of Colorado at Boulder and a researcher. principal of SISTINE. in the statement.

The sun, seen in extreme ultraviolet light by NASA’s Solar Dynamics Observatory. (Image credit: SDO/NASA)

The three sounding rocket launches from Arnhem Space Center are the first launches NASA has conducted from a commercial spaceport outside the United States. (NASA has launched from Australia before – most recently, in 1995 – but these rockets took off from the Royal Australian Air Force Woomera Range Complex.)

“This commercial launch range in Australia opens up new access to the Southern Hemisphere night sky, expanding the possibilities for future science missions,” Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate, said in a statement. . statement (opens in a new tab).

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