[meteorite-list] Japan's Hayabusa 2 Asteorid Mission Checks Out

[Ron Baalke]

http://spaceflightnow.com/2015/03/09/japans-hayabusa-2-asteroid-mission-checks-out/

Japan's Hayabusa 2 asteroid mission checks out
by Stephen Clark
SpaceFlight Now
March 9, 2015

Three months into an interplanetary cruise expected to last three-and-a-half 
years, Japan's $300 million Hayabusa 2 mission is in good health as it 
begins an ion-powered pursuit of an asteroid to return a piece of it to 
Earth.

The robotic spacecraft is already traveling more than 20 million miles 
from Earth after launching Dec. 3, and Japanese officials say the probe 
has passed health checks and is ready for the long-distance journey ahead.

The Hayabusa 2 spacecraft "completed its initial functional confirmation 
period on March 2, 2015, as all scheduled checkout and evaluation of acquired 
data were completed," the Japan Aerospace Exploration Agency said in a 
statement. "The explorer has been under inspection for about three months 
after its launch on Dec. 3, 2014."

The probe carries four ion thrusters to nudge it on course toward asteroid 
1999 JU3, a carbon-rich world just 900 meters - about 3,000 feet - across 
with a tenuous gravity field 60,000 times weaker than Earth's.

The engines produce little thrust, but the units can be operated for thousands 
of hours, building up energy to reshape Hayabusa 2's path around the sun.

JAXA says two of the ion engines will fire for about 400 hours in March 
to give the spacecraft a boost. Two thrusters will be operated again in 
early June.

The two periods of near-continuous propulsion will change the probe's 
velocity by about 60 meters per second, or 134 mph, to align Hayabusa 
2 with an encounter with Earth in December. The close flyby of Earth will 
use the planet's gravity to slingshot Hayabusa 2 toward its destination, 
where it is due to arrive in June 2018 after more firings of the craft's 
ion engines.

Since Hayabusa 2's launch in early December, ground controllers tested 
the probe's X-band and Ka-band communications systems, batteries, science 
instruments, reaction wheels, and all four ion engines. Hayabusa 2 also 
extended its sampling device in preparation for scooping up material at 
the asteroid.

[Graphic]
Diagram of the positions of Earth, Hayabusa 2, and asteroid 1999 JU3 as 
of March 3, 2015. Credit: JAXA

Engineers tested Hayabusa 2's German-built lander named MASCOT built by 
the same team that managed the Philae comet lander, which was carried 
aboard Europe's Rosetta spacecraft and touched down on comet 
67P/Churyumov-Gerasimenko in November.

Three other landing craft built in Japan will also descend to the asteroid 
during Hayabusa 2's mission.

The landers are mobile and will use mechanisms to hop across the asteroid 
to study its environment from several locations.

Hayabusa 2 will spend a year-and-a-half at asteroid 1999 JU3, enough time 
for the probe to pick up rock specimens from three different locations 
on the unexplored asteroid.

Once the mission's work at the asteroid is complete, Hayabusa 2 will leave 
and head for Earth in December 2019.

Hayabusa 2 will release a container with the asteroid samples for a blazing 
re-entry through Earth's atmosphere for a parachute-assisted landing in 
the Australian outback in December 2020.