According to the now accepted model, planets are formed by the gradual accretion of smaller objects - and Pluto, situated right next to the Kuiper Belt asteroid field, has always been thought to have formed the same way.
Pluto may not be categorised as a planet any more, but it still holds plenty of fascination.
Pluto, however, could be breaking the mould, formed not from dust, but from comets-a billion or so-according to research published May 23.
Glein and his SwRI colleague Hunter Waite devised the new Pluto-formation scenario after analyzing data from Rosetta and NASA's New Horizons mission, which flew by Pluto in July 2015.
" We discovered an appealing consistency in between the approximated quantity of nitrogen inside the [Sputnik Planitia] glacier and the quantity that would be anticipated if Pluto was formed by the pile of approximately a billion comets or other Kuiper Belt things comparable in chemical structure to 67P, the comet checked out by Rosetta", discussed Glein in a declaration.
Did Pluto form like its closer-in brethren in the solar system, or is it the result of an agglomeration of comets from the edge of the solar system? Long considered the ninth official planet, astronomers who redefined what "planet" really means chose to reclassify Pluto in 2006 as a "dwarf planet".
"We've developed what we call "the giant comet" cosmochemical model of Pluto formation", said geochemist Christopher Glein of the SwRI's Space Science and Engineering Division. It considers a possibility that Pluto made up of very cold ices that have chemical composition similar to the Sun. Apart from detecting nitrogen on Pluto's surface, they also need to understand how much of it could have leaked out in space. They then needed to reconcile the proportion of carbon monoxide to nitrogen to get a more complete picture.
The solar model for Pluto's formation hasn't yet been completely ruled out, however.
The researchers further suggest that the presence of liquid water may have altered the planet over time, even going so far as to propose that the planet may have had a subsurface ocean. Ultimately, the low abundance of carbon monoxide at Pluto points to burial in surface ices or to destruction from liquid water.
New Horizons has already moved on toward its next target.
"Utilizing chemistry as a detective's software, we're in a position to hint sure options we see on Pluto right this moment to formation processes from way back", he added. It is found that the cometary model can account for the amount of N2 in Sputnik Planitia, while the solar model can provide a large initial inventory of N2 that would make prodigious atmospheric escape possible.