Back in 2019 , NASA ’s New Horizons probe flew by Arrokoth , a two - lobed small object in the Kuiper Belt far beyond Neptune . Observations of the object reveal mounds on the surface of the lobe and their size , shape , and composition . They are all remarkably similar , hint that these were the original building block for this far - away world .
The objective is made of two different size lobes , call Wenu ( the large ) and Weeyo ( the smaller ) – it looks a bit like two hamburger stick together . On its longest axis of rotation , it is 36 kilometers ( 22 miles ) across . The team identified 12 mounds of about 5 kilometers each in length that make up Wenu , and possibly three in Weeyo , though the latter could not be well - characterise in the study . The analysis , however , shows them to be exceedingly standardised and the squad does n’t believe this is an accident .
“ law of similarity including in size and other properties ofArrokoth’smound social structure evoke new insights into its constitution , ” Dr Alan Stern , the principal police detective of the New Horizons mission , enjoin in astatement . “ If the hillock are indeed representative of the building blocks of ancient planetesimals like Arrokoth , then planetesimal organization models will need to explain the preferent size for these building blocks . ”
The establishment model sees these freehanded chunks of space material having come together very slowly , not much fast than a somebody on a gentle jog . Once they clash , they bit by bit merge into what we now call Arrokoth , a smallworld44.5 times further by from the Sun than the Earth . It has not change much over billions of years .
“ It ’s awful to see this object so well preserved that its shape directly reveals these details of its assemblage from a set of building block all very like to one another , ” supply Lowell Observatory ’s Dr Will Grundy , Centennial State - investigator of the New Horizons commission . “ Arrokoth almost looks like a raspberry bush , made of little submarine - units . ”
Upcoming missions , like NASA’sLucymission , launch two years ago and the European Space Agency ’s Comet Interceptor , will have a chance to read pristine planetesimal that should n’t have changed much . This might provide more insight into how these worlds came to be .
“ It will be important to research for mound - like structures on the planetesimals these missions observe to see how vernacular this phenomenon is , as a further guidebook to planetesimal formation theories , ” Stern conclude .
The study is publish inThe Planetary Science Journal .
