Artist's concept of OSIRIS-REX collecting a sample from Bennu. Illustration: NASA Goddard Space Flight Center NASA's OSIRIS-REX mission will not…
Artist’s concept of OSIRIS-REX collecting a sample from Bennu. Illustration: NASA Goddard Space Flight Center
NASA’s OSIRIS-REX mission will not just take pretty pictures of the asteroid Bennu-it will also help scientists learn whether the rock will threaten one day Earth.
There are plenty of reasons to study asteroids. De kan være potensielle mines for dyrebare ressourcer som vand og tungelementer, og de indeholder clues vi kan studere for at lære det solsystem var som i sine tidligste dager. Men også, store ting slamming i jorden kan have nogle katastrofale konsekvenser. So scientists are interested in that too.
Bennu is a 1,600-foot-wide asteroid that orbits the Sun relatively close to the Earth. OSIRIS-REX, the NASA mission tasked with studying it, launched in September 2016 and arrived at its target this past Monday. The spacecraft carries five instruments: a camera suite, a LIDAR system (like radar, but with a laser instead of radio waves), and three spectrometers, which measure different wavelengths of light to determine the asteroid’s composition.
Bennu is an especially important target when it comes to our own survival. Around every six years, it comes relatively close to the Earth (“close” in cosmic terms, but very far by any other measure). Models suggest that during its close approaches between the years 2175 and 2196, it has a 1 in 2,700 chance of colliding with us. That’s still incredibly small, but Bennu is a big rock-even smart odds are too great to ignore when civilization is at stake.
Why do not astronomers know for sure whether we’re safe? There are plenty of forces to stake, and small differences can change the odds. Under noen af de asteroids nærtangreb, jordens tyngdekraft vil give det et nudge som kunne flytte det til en sammenføyningskurs. Videre er det Yarkovsky-effekten, ifølge en Jet Propulsion Lab pressemeddelelse: den ujevne oppvarmingen fra solen på et slikt lett kropp kan forårsake forandringer i sin trajectory. It’s unclear where Bennu will go after 2135.
OSIRIS-REX and telescopes on Earth will continue to characterize the asteroid, tracing its path and determining how gravity and the Yarkovsky effect will affect its trajectory. The mission will hopefully produce trajectories 60 times more accurate than present-day estimates, according to the press release.
So what happens if Bennu becomes a threat? Well, you personally should not worry, because the odds are very good that you will be dead. Your children, too, will probably be dead (American life expectancy is declining so do not tell me that it’s a sure thing that we’ll live longer in the future). Men forskerne arbejder på et par løsninger. En mission, som kalles The Double Asteroid Redirection Test, vil forsøke å slam en romfartøy inn i en asteroid for å forårsake en trajectory forandring. Maybe we could nuke asteroids. Or, om vi får nok tid, kan vi bare male en side for at ændre hvordan det absorberer solstråling, ved hjælp af Yarkovsky-effekten til vores fordel.
There are lots of data to be taken before we know what Bennu will do, and plenty of other interesting science to conduct. Men vet at Bennu er ikke den asteroide som du bør være bekymret for. The asteroids you should worry about are the ones that have not been detected yet.