At the edge of space

It's been a fascinating couple of weeks out at the furthest reaches of the solar system.

On New Years Day, the spacecraft New Horizons achieved flyby of the distant planetoid Ultima Thule (2014 MU69). You will recall that back in the summer of 2015, New Horizons made the most distant planetary flyby in history when it reached Pluto, taking shots in unprecedented detail. It's spent the last three-and-a-half years travelling ever outward, finally making it to Ultima Thule at a distance of 43 AU, or six light hours. The orbits of the two planetoids cross, and they are favourably positioned to one another during the spacecraft's window of opportunity.

Ultima Thule is a funny little planetoid. It's snowman-shaped, formed when two objects fused in a slow collision billions of years ago. It's nickname refers to a Latin phrase which became the name of the legendary northernmost point of the ancient world. NASA have also named the original planetesimals that came together Ultima and Thule (for the larger and smaller respectively) which is cute. Ultima Thule is only 31 km long at its greatest extent, and is a snapshot of the initial building blocks of the solar system, that came together to form larger planetoids and planets. NASA are now studying the data sent back for information on its composition, surface temperature and geology, and any evidence for rings, moonlets or a cometary coma.

The next destination for New Horizons remains to be seen, but it has power enough to remain operational until around 2030 and should be able to complete a final planetary flyby once a suitable, very distant target has been identified.

New Horizons is the fastest travelling spacecraft (in terms of initial speed) in NASA history, and is even catching up with the earliest space probes that were launched in the 1970s. Voyager 2 left the heliopause, officially entering interstellar space, in November (it's brother Voyager 1, although launched a little later, passed it and reached the threshold earlier). The Voyagers were be joined in interstellar space by New Horizons in the next few decades, as well as the now defunct Pioneer probes. NH will eventually pass the Pioneers (by the 23rd century, which is when Pioneer 10 is due to be destroyed by the Klingons), but will never catch up with the Voyagers.

Also in November, three astronomers (Sheppard, Tholen and Trujillo) observed the most distant trans-Neptunian planetary object ever. Officially designated 2018 VG18, but nicknamed Farout, the object is the first to be detected at a distance of over 100 AU. Currently at a distance of 120 AU, it beats Eris at an observed distance of 96 AU. In terms of average distance though, it is more than double that of Eris, although not nearly the farthest discovered. In 2014, the same team discovered FE72 which has a semi-major axis of a wahopping 1550 AU.

It's a fascinating time to be learning about the very fringes of our solar system.

The State of the Universe

I didn't even realise that there were such things as gamma ray constellations. NASA's Fermi telescope team are creating a map of the sky that groups gamma ray sources - pulsars, black holes and blazars - into handy, recognisable images, just like we have with stars. The difference is that the Fermi team are naming their constellations after pop culture icons, among other recognisable things, including Godzilla (above), the TARDIS and the Starship Enterprise.

This is just one of a number of fascinating developments in astronomy and the space sciences. The wonderfully named BepiColombo has been launched on an Ariane 5 rocket and is headed towards Mercury. This new mission to visit the woefully underexplored innermost planet of the solar system is an historic joint endeavour between the European Space Agency and its Japanese equivalent JAXA. The ship is going to take over five years to spiral towards Mercury (the ESA website has a handy video illustrating the multiple flybys it will take to get there). The long, looping journey is necessary to avoid being pulled into the intense gravity well of the Sun.

The surface of Ryugu

JAXA is on a role, with their asteroidal survey ship Hayabusa2 now happily exploring near-Earth asteroid Ryugu, sending back data, images and even video of the surface. After four years travelling to the asteroid on its orbital path between Earth and Mars, Hayabusa2 will return to Earth carrying samples collected from its four robotic rovers. Three, of the MINERVA-II project and named simply ROVER-1A, 1B and 2, were developed by JAXA, while the Mobile Asteroid Surface Scout (MASCOT) currently charting the unusual geological and magnetic properties of the asteroid was built by a joint German-French initiative. ROVER-1A has taken the first ever images from the surface of an asteroid.

The Planetary Society also worked with JAXA to include messages to be imprinted on a marker that will be left on the surface of the asteroid. There was an opportunity to submit names to be included - my name, along with my brother's and sister's names, are now on Ryugu!