Asteroid Ryugu Likely Link in Planetary Formation

Formation scenario for Ryugu. More than one year ago, the Japanese Hayabusa2 orbiter deployed the German lander, MASCOT, which investigated the approximately one-kilometre-diameter asteroid Ryugu. Scientists are now imagining the history of its formation 4.5 billion years ago. First, flakes and grains of dust formed in the disc of dust and gas rotating around the Sun (1), before porous planetesimals agglomerated due to the accretion of these loose flakes (2). Recent investigations suggest that Ryugu’s parent body hardly condensed and was also highly porous. This may have resulted in the formation of a firmer core, but scientists also believe that a gradual increase in density towards the centre of the parent body is conceivable (3). Impacts and collisions with other asteroids (4) led to a fragmentation of the parent body; the large boulders on Ryugu probably originated here. Part of the debris was then the source material for the accretion of Ryugu (5), with porous blocks and loose material, and also some more compact blocks of higher density from the original core, some of which remain on the surface. Ryugu‘s present diamondlike shape (6) occurred over time due to its rotation. (Credit: Okada et al. Nature 2020)
  • Infrared images show that Ryugu is almost entirely made up.
  • The asteroid was formed largely from fragments of a parent body that was shattered by impacts of highly porous material.
  • DLR scientists participate in the publication in the scientific journal Nature.

COLOGNE, Germany (DLR PR) — The Solar System formed approximately 4.5 billion years ago. Numerous fragments that bear witness to this early era orbit the Sun as asteroids. Around three-quarters of these are carbon-rich C-type asteroids, such as 162173 Ryugu, which was the target of the Japanese Hayabusa2 mission in 2018 and 2019. The spacecraft is currently on its return flight to Earth.

Numerous scientists, including planetary researchers from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), intensively studied this cosmic ‘rubble pile’, which is almost one kilometre in diameter and can come close to Earth. Infrared images acquired by Hayabusa2 have now been published in the scientific journal Nature. They show that the asteroid consists almost entirely of highly porous material.


NASA Receives 12 Proposals for Solar System Exploration Missions

WASHINGTON, DC (NASA PR) — NASA has received and is reviewing 12 proposals for future unmanned solar system exploration. The proposed missions of discovery – submitted under NASA’s New Frontiers program – will undergo scientific and technical review over the next seven months. The goal is to select a mission for flight in about two years, with launch in the mid-2020s.


Postal Service Releases Pluto—Explored! and Views of Our Planets Forever Stamps

Credit: USPS
Credit: USPS

NEW YORK CITY — Less than a year following NASA’s nine-year, three-billion plus mile New Horizons mission to explore Pluto, the U.S. Postal Service dedicated Forever stamps to commemorate the historic event, while dedicating a second set of stamps depicting NASA’s stunning images of our planets.

The first-day-of-issue dedication ceremony for the Pluto—Explored! and Views of Our Planets Forever stamps took place before a crowd of 500 at the world’s largest stamp show that only occurs in the United States once a decade, World Stamp Show-NY 2016. The show runs through Saturday. The public is asked to share the news on social media using the hashtags #PlutoExplored and #PlanetStamps. Visit  Our Planets Forever Stamps to view images of the stamps and background on the planets.


Pluto: No Longer a Dwarf, But Still Not a Planet

Pluto and its satellite, Charon, in happier times. Image credit: Dr. R. Albrecht, ESA/ESO Space Telescope European Coordinating Facility; NASA.

It looks like it is time to revise those astronomy textbooks once again. For the second time in as many years, the world’s astronomers have reclassified Pluto. The International Astronomical Union has issued a statement saying that small bodies such as Pluto would be known by a new name: plutoid.

Two years ago, the IAU sparked a major controversy by reclassifying the distance world as a dwarf planet. The decision seemed especially upsetting to many schoolchildren, who identify with the tiny world that hovered forever on the periphery of a Solar System populated by much larger, grown up planets.

Whether this latest decision will mollify or mystify children is yet to be seen. However, it doesn’t really remove the confusion over why the IAU just didn’t leave well enough alone two years ago. Pluto orbits the sun, has an atmosphere, and possesses three satellite (including one, Charon, that’s half its size). In other words, it seems to fit most people’s definition of a planet. Why the change?

What was really confusing, however, was why astronomers would tempt fate by demoting a planet named after the Roman god of the underworld. One assumes they’re not very superstitious. Otherwise, they might be a tad worried that Pluto will exact his revenge on them, if not in this life then definitely in the next.