Hayabusa2 is approaching Ryugu! Here's how to stay on top of the mission.
As I write this, fewer than 21,000 kilometers separate the Hayabusa2 spacecraft from its asteroid target, Ryugu, and it's approaching the asteroid at a speed of 40 meters per second -- only about 150 kilometers per hour. I have always paired Hayabusa2 and OSIRIS-REx in my mind, because they are both sample-return missions approaching their target asteroids in summer 2018. But Hayabusa2 will already have touched down on its asteroid by the end of 2018, while OSIRIS-REx will still be surveying Bennu from a distance at the end of the year. It's time for those of us who've been sleeping on Hayabusa2 to wake up and pay attention!
Hayabusa2 at asteroid 1999 JU3
The official Hayabusa2 website offers much more information in English than JAXA has ever offered for previous missions. That's work being done by Elizabeth Tasker, a British astrophysicist who is working for JAXA to help them with English-language outreach. You can find her on Twitter at @girlandkat, and she runs the official English-language Hayabusa2 Twitter account, @haya2e_jaxa. Another Twitter account to follow is @MASCOT2018, the official account for the German-built lander.
Hayabusa2's schedule is a little difficult to predict because the asteroid's shape isn't known yet; they'll be planning survey and touchdown activities in response to what they discover. With that disclaimer, here's the provisional schedule for the rest of 2018.
Early June: At a distance of 2500 kilometers, the "approach" phase officially begins, and ion engine operation ends. They will coast the rest of the way toward Ryugu. If you divide today's 21,000 kilometers by 0.04 kilometers per second, I get Hayabusa2 approaching to within 2500 kilometers of the asteroid on May 29 or 30, but of course they are using the ion engines now to slow down the rate at which they are closing with the asteroid.
June 21-July 5: Hayabusa2 arrives at Ryugu, approaching to within 20 kilometers.
End of July: Hayabusa2 descends to a distance of 5 kilometers to perform medium-altitude observations.
August: Hayabusa2 descends to only 1 kilometer to measure Ryugu's gravity close-up (necessary to prepare to land on it)
September-October: Period for first touchdown operation. One or more of Hayabusa2's three MINERVA-II rovers and/or the European-built MASCOT lander may be released at this time.
November-December: Solar conjunction, no communications
I won't reproduce the rest of the currently posted timeline because I bet there'll be changes to it between arrival and the planned departure date of November or December of 2019.
For background reading, I suggest Spaceflight101's Hayabusa2 explainer. Also please enjoy the other Hayabusa2 imagery I've already gathered in our image library; I'll add to the collection over the coming months. Here also is a nice video explainer of Hayabusa2's remote sensing instruments
Video tour of Hayabusa2's science instruments
Hayabusa2 has four instruments for science observations: a suite of optical navigation cameras (ONC); a near-infrared spectrometer (NIRS3); a thermal infrared imager (TIR); and a laser altimeter.
And another nice video from DLR showing how the MASCOT micro-lander will work:
MASCOT mission animation
MASCOT (Mobile Asteroid Surface Scout) is an asteroid lander built by the German space agency DLR for the Hayabusa2 mission. It is tiny, only 30 by 30 by 20 centimeters in size, weighing 10 kilograms. It has an internal motion mechanism that will allow it to hop across the surface of asteroid Ryugu.
Finally, enjoy yourself by making a paper model of Hayabusa2! It's a simple one suitable for kids. I'm going to have to get going on my usual needlepoint-and-plastic-canvas scale model! I wonder if I can make one with a deployable MASCOT...