On the 8th of September, US space agency Nasa launched its Osiris-Rex probe on a 7-year journey to collect samples from an asteroid called Bennu. The hope is that the samples from Bennu will provide clues about the movement of dangerous objects through the solar system, and lead to discoveries about the formation of planets. Scientists hope to collect as much as a few hundred grams of material from the asteroid, significantly more than when the Japanese performed a similar mission to collect asteroid material in 2010.
A collection device, attached to a robotic arm, will use a burst of gas to kick up dust and fragments from the asteroid, which it will collect in a holding chamber. The return capsule will bring this material back to earth, parachuted into the Utah desert on September 24, 2023.
Assessments using telescopes have determined that the asteroid may be rich in carbon compounds. Christina Richey, Nasa’s deputy program scientist for the project, says that “for primitive, carbon-rich asteroids like Bennu, materials are preserved from over 4.5 billion years ago. We’re talking about the formation of our Solar System. And these primitive materials could contain organic molecules that may be the precursors to life here on Earth or elsewhere within our Solar System.”
Sample-Return missions provide scientists with a much greater opportunity to study substances than the use of traditional probes. The level of sophistication and precision which scientists have at their disposal in a lab on earth can be impossible to reproduce on an unmanned probe in space. This greatly limits the information that such missions are able to gather on site, in space, using only robotics. Dating substances in particular is impossible to accomplish this way, meaning chronology work must be done on earth, in a laboratory environment.
Osiris-Rex will remain at Bennu for two and a half years to collect its samples.
Another part of its mission is to investigate a phenomenon called the “Yarkovsky effect”, which describes how the path of an asteroid is altered when it is heated by the sun, once it enters the solar system. Dante Lauretta, who is the mission’s principle investigator, explained that when the surfaces of asteroids are heated by the sun, they radiate the energy back into space, which, like a thruster, can alter the trajectory of the asteroid. “If you want to be able to predict where an object like Bennu is going to be in the future, you have to account for this phenomenon,” she says. This knowledge could be instrumental in determining the paths of dangerous objects moving through space.