[meteorite-list] Japan Prepares For Second Asteroid Sample Return (Hayabusa 2)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 28 Mar 2013 08:48:03 -0700 (PDT)
Message-ID: <201303281548.r2SFm33k006558_at_zagami.jpl.nasa.gov>

http://www.spaceflightnow.com/news/n1303/27hayabusa2/

Japan prepares for second asteroid sample return
BY STEPHEN CLARK
SPACEFLIGHT NOW
March 27, 2013

HOUSTON -- Japanese engineers hurriedly redesigned the rock-collector
and science payloads on the Hayabusa 2 spacecraft set to launch on an
asteroid-sampling mission in late 2014, hoping to trump a problem which
limited the load of asteroid rock fragments brought home by a preceding
mission.

With the launch of Hayabusa 2 scheduled in less than 2 years, engineers
did not have time to make major alterations to the probe based on
lessons learned from the Hayabusa mission, which returned the first
samples from the surface of an asteroid to Earth in June 2010, according
to Shogo Tachibana, a researcher from Hokkaido University in Japan and
lead scientist for the Hayabusa 2 sampling system.

The 1,320-pound Hayabusa 2 probe, slightly larger than the preceding
Hayabusa spacecraft, is due for launch on a Japanese H-2A rocket in
December 2014, and its destination is asteroid 1999 JU3, an object about
3,000 feet in length. Hayabusa 2 will arrive at 1999 JU3 in 2018 and
loiter around the asteroid for about 18 months. Hayabusa spent about
three months near asteroid Itokawa, a smaller rock than 1999 JU3.

After up to three close approaches to acquire samples, Hayabusa 2 will
depart the asteroid and deploy a sample-bearing re-entry capsule into
Earth's atmosphere in December 2020.

Although the first Hayabusa mission made history, it collected
substantially fewer samples than expected because the spacecraft's
rock-gathering device failed to function when the probe approached Itokawa.

Hayabusa also suffered from a crippling fuel leak, ion engine failures,
reaction wheel problems, battery issues and a break in communications
with Earth for two months, and Japanese officials grew concerned they
would lose the spacecraft.

But controllers delayed Hayabusa's return to Earth by three years,
buying time for engineers to devise a method of using the craft's
remaining ion propulsion engines to control its orientation and guide
the probe home.

When scientists opened Hayabusa's re-entry capsule after it landed in
Australia, they found more than 1,500 tiny rock and soil grains, most of
which were confirmed to be from Itokawa.

Launched in May 2003, Hayabusa made two descents toward Itokawa in late
2005 to collect samples, and the spacecraft was supposed to fire a
tantalum pellet into the asteroid and scoop up bits of rock blasted away
by the projectile.

The tantalum bullet did not fire on either sampling attempt, and
scientists feared the mission was a failure.

But an analysis of telemetry from Hayabusa showed the probe
inadvertently landed on the asteroid for up to a half-hour, leaving
officials hopeful some surface specimens made their way through the
craft's sampling horn and into a collection chamber.

It turns out that is what happened.

Japanese engineers recover the sample return capsule from the Hayabusa
mission in Australia. Credit: JAXA
 
Before the Hayabusa probe returned to Earth, scientists proposed a
follow-on mission named Hayabusa 2, which received approval from the
Japanese government in January 2012.

But with the mission slated to launch in late 2014, engineers had to
prioritize what upgrades to make to the spacecraft, which will use much
the same technology flown on Hayabusa.

Like its predecessor, Hayabusa 2 carries four ion engines, but the
efficient electrically-propelled engines will generate more power on the
new spacecraft. And Hayabusa 2 will have a Ka-band communications
antenna to beam data and imagery back to Earth at higher speeds than
Hayabusa, according to Makoto Yoshikawa, Hayabusa 2's project manager at
the Japan Aerospace Exploration Agency.

NASA's Deep Space Network will support communications with the Japanese
probe.

And with the benefit of a decade's progress in computer development,
Hayabusa 2 will use upgraded software to keep the probe resilient to
faults caused by radiation and other threats.

Once it arrives at asteroid 1999 JU3, Hayabusa 2 will survey the rock
with an array of instruments, including imagers, a spectrometer, and a
terrain-mapping altimeter.

The craft will also release a small Japanese rover named MINERVA to hop
across the surface of the asteroid and deploy the MASCOT lander
developed by the German Aerospace Center, or DLR.

Led by the DLR Institute of Space Systems in Bremen, Germany, with
support from the French space agency, the Mobile Asteroid Surface Scout
will measure the asteroid's magnetic field, surface temperature, rock
composition, and take pictures during descent and after landing,
according to a presentation by Ralf Jaumann, a planetary scientist at DLR.

Scientists will compare data from MASCOT and the Japanese lander to
analyses of samples returned to Earth by Hayabusa 2.

Hayabusa 2's destination is a different type of miniature world than
Itokawa. Asteroid 1999 JU3 is a C-type asteroid, a classification of
primitive objects made of organic and hydrated minerals

Itokawa is an S-type asteroid composed of rocks and metals heated and
modified over the solar system's 4.5 billion year history, causing the
material to lose chemical markers left over from the dawn of the solar
system.

Scientists expect the Hayabusa 2 samples to hold a record of the
tumultuous early phases of the solar system's formation, including the
basic building blocks of life such as amino acids.

"These C-type asteroids could be the bridge from the start of the
evolution of the solar system to the beginning of life on Earth,"
Tachibana said in an interview at the 44th Lunar and Planetary Science
Conference near Houston.
 
Mission planners designed Hayabusa 2 to make three sampling attempts at
its target asteroid, one more than Hayabusa made at Itokawa. On each
attempt, Hayabusa 2 will approach 1999 JU3 at low speeds and try to
scoop up pebbles with a 3-foot-long sampling horn during brief
touchdowns on the asteroid.

Two of the sampling attempts will focus on regions identified to be rich
in hydrated, water-rich minerals and organic molecules. Hayabusa 2's
sampling system will fire a tantalum projectile into the asteroid to
kick up rocks into the 5.5-inch opening of a funnel leading into a
storage container.

The sampling gun did not fire on Hayabusa's visit to asteroid Itokawa,
limiting the probe's haul of samples for return to Earth to tiny grains
of dust. Engineers blamed the failure on a software coding error.

Tachibana is confident the tantalum bullet will fire on Hayabusa 2, but
even with another glitch, engineers devised a backup method to ensure
the probe comes home with more samples than Hayabusa. The end of the new
sampling horn has teeth like a comb to dig into the asteroid's gravely
surface to pick up some material even if the sampling gun does not fire,
according to Tachibana.

"Even if the bullet does not shoot, as long as we touch down, we will
get samples," Tachibana said.

Hayabusa 2 will collect a third sample with the help of a small copper
impactor, which was not aboard the Hayabusa mission to Itokawa.

Slamming into the asteroid at more than 4,000 mph, the grapefruit-sized
impactor will blast a crater and excavate material from beneath the
rock's surface. After the collision, Hayabusa 2 will glide to a soft
landing at or near the impact site, collecting material from the
newly-formed crater.

Scientists say the subsurface samples are more pristine than surface
rocks, which are exposed to weathering from radiation and the solar wind.

Each sample will be funneled into three separate holding chambers to
separate the specimens, then the containers will be sealed to trap
volatile compounds like hydroxides.

Depending on the texture of the rocks on 1999 JU3, Hayabusa 2 should
pick up between a gram and several grams of samples.

That is much less than the 60-gram, or 2.1-ounce, sampling goal of
NASA's OSIRIS-REx asteroid mission scheduled for launch in September
2016. Some scientists say OSIRIS-REx could corral more than 4 pounds of
asteroid material under the right conditions.

"We get much less samples than OSIRIS-REx, but we think we can do a lot
of science with our samples," Tachibana said. "Of course, we want to
have more."

OSIRIS-REx is targeting another primitive carbon-rich asteroid similar
to Hayabusa 2's target. It will arrive at asteroid 1999 RQ36 in 2020 and
return to Earth in 2023.

Tachibana said OSIRIS-REx and Hayabusa 2 are complementary.

"They get more samples, but we get samples with better quality,"
Tachibana said, adding that Hayabusa 2's sample container has the
advantage of differentiating each batch of asteroid material from three
sampling attempts.
Received on Thu 28 Mar 2013 11:48:03 AM PDT