NASA is launching a new CHESS sounding rocket on June 27 which will study vast interstellar clouds to understand more about the earliest stages of star formation. CHESS – short for the Colorado High-resolution Echelle Stellar Spectrograph – is a sounding rocket that will fly on a Black Brant IX suborbital sounding rocket. Deep in space between distant stars, space is not empty. Instead, there drifts vast clouds of neutral atoms and molecules, as well as charged plasma particles, called the interstellar medium – that may, over millions of years, evolve into new stars and even planets. CHESS will measure light filtering through the interstellar medium to study the atoms and molecules within, which provides crucial information for understanding the lifecycle of stars.
“The interstellar medium pervades the galaxy,” said Kevin France, from the University of Colorado, Boulder in the US. “When massive stars explode as supernovae, they expel this raw material. It’s the insides of dead stars, turning into the next generation of stars and planets,” said France. CHESS is a spectrograph, which provides information on how much of any given wavelength of light is present. It will train its eye at Beta Scorpii – a hot, brightly shining star in the Scorpius constellation well-positioned for the instrument to probe the material between the star and our own solar system. As light from Beta Scorpii streams toward Earth, atoms and molecules – including carbon, oxygen and hydrogen – block the light to varying degrees along the way.
Scientists know which wavelengths are blocked by what, so by looking at how much light reaches the space around Earth, they can assess all sorts of details about the space it travelled through to get there. CHESS data provides observations such as which atoms and molecules are present in space, their temperatures and how fast they are moving. The scientists also use CHESS data to evaluate how the interstellar cloud is structured, which can help them pinpoint where it stands in the process of star formation. It is still not known exactly how long it takes for this material to be incorporated into new stars. However, scientists know dense clouds can pave the way for the collapse at the very beginning of star formation.
The flight of a sounding rocket is a short one; CHESS will fly for about 16 minutes total. Just six-and-a-half of those minutes are spent making observations between 144 and 321 kilometres above the surface – observations that can only be made in space, above the atmosphere, which the far-ultraviolet light that CHESS observes can not penetrate. After the flight, the payload parachutes to the ground, where it can be recovered for future flights. This is the third flight for the CHESS payload in the past three years, and the mission’s most detailed survey yet.