[meteorite-list] Hayabusa Begins Daring Close Encouter WithAsteroid

From: K. Ohtsuka <ohtsuka_at_meteoritecentral.com>
Date: Wed Sep 14 20:46:18 2005
Message-ID: <001c01c5b98e$cea5e3c0$347e76da_at_LocalHost>

Hello Jeff-san
You can find Itokawa's latest image(s) at the following site:

http://www.isas.ac.jp/e/snews/index.shtml

K. Ohtsuka, Tokyo Meteor Network

----- Original Message -----
From: "Jeff Kuyken" <info_at_meteorites.com.au>
To: "Ron Baalke" <baalke_at_zagami.jpl.nasa.gov>; "Meteorite Mailing List"
<meteorite-list_at_meteoritecentral.com>
Sent: Thursday, September 15, 2005 9:02 AM
Subject: Re: [meteorite-list] Hayabusa Begins Daring Close Encouter
WithAsteroid


> Hi List,
>
> Does anyone have a link to images that Hayabusa is sending back?
>
> Thanks,
>
> Jeff
>
>
> ----- Original Message -----
> From: Ron Baalke
> To: Meteorite Mailing List
> Sent: Thursday, September 15, 2005 9:27 AM
> Subject: [meteorite-list] Hayabusa Begins Daring Close Encouter With
> Asteroid
>
> http://www.spaceflightnow.com/news/n0509/14hayabusa/
>
> Probe begins daring close encounter with asteroid
> BY STEPHEN CLARK
> SPACEFLIGHT NOW
> September 12, 2005
>
> A $100 million Japanese space explorer parked in the vicinity of an
> enigmatic asteroid this week, allowing scientists to get a first glimpse
> of the mid-sized rock that will become the source of the first samples
> of such an object to ever be returned to Earth.
>
> After methodically tweaking its course - first by electrical ion
> propulsion, then by conventional chemical thrusters - toward its target
> over the past few months, the Hayabusa probe finally arrived at its
> station keeping position some 12 miles from the asteroid early Monday.
>
> Officials timed the arrival by when the 1,000-pound craft's closure rate
> relative to the object reached zero, indicating the probe was now
> essentially anchored in the "gate position" located about 12 miles from
> the space rock. That moment occurred as the spacecraft commanded its
> maneuvering jets to fire one last time at about 0117 GMT Monday, or in
> the late-morning hours in Japan.
>
> Hayabusa's ion drive propulsion system took a the leading role for the
> rendezvous up until August 28, when control switched to the
> liquid-fueled chemical thrusters. That milestone left the four ion
> engines with a cumulative burn time of almost 26,000 hours, and the
> system will be re-started once the probe embarks on the last leg of its
> journey back to Earth.
>
> The delicate space ballet took place almost 200 million miles from
> controllers on Earth, who left responsibility for the rendezvous to an
> on-board navigation system that is designed to operate without ground
> intervention.
>
> The goal of the mission is to study asteroid 1998 SF36 - later named
> Itokawa in honor of an early Japanese pioneer in rocketry. The object
> was discovered in September 1998 by a joint team consisting of
> scientists from the U.S. Air Force, NASA, and the Massachusetts
> Institute of Technology.
>
> Details about Itokawa have largely remained elusive in the seven years
> since its discovery, but scientists now have a much clearer picture of
> the potato-shaped asteroid estimated to measure 2,000 feet by around 900
> feet. Its orbit stretches from inside Earth's out to a distance of 157
> million miles from the Sun, making it a member of the Apollo class of
> near-Earth asteroids that pose potential impact threats to our planet.
>
> Astronomers studied Itokawa via several ground-based telescopes during
> its last Earth fly-by in 2001, and they found evidence that the asteroid
> was brighter and more reflective than first expected. Scientists had a
> difficult time predicting what Hayabusa would find as it closed in on
> the object, and many questions were left unanswered.
>
> However, many of those issues can now be thoroughly remedied with the
> new higher resolution images Hayabusa's optical asteroid multi-band
> imaging camera has captured. The pictures show a contrast of rocky and
> hilly terrain with smooth regions, but detailed analysis and sample
> retrieval will be conducted before scientists can announce the results
> of their detailed study.
>
> A first look at the new images appears to show a loose layer of dust and
> dirt-like material covering the smooth surfaces of parts of the
> asteroid, which is a surprise to some project officials.
>
> "According to a certain theory, small objects do not have regolith,"
> said Hayabusa project manager Jun Kawaguchi. "But this asteroid seems to
> have smooth portions that appear (to have) some regolith."
>
> Work with Hayabusa's science payload has already begun, with the
> near-infrared and X-ray spectrometers now gathering measurements. The
> craft's laser altimeter is also conducting observations to learn more
> details about Itokawa's terrain.
>
> The pair of spectrometers will labor to determine the elemental and
> mineral composition of Itokawa to help astronomers in their quest to
> link asteroids and comets to meteorites that have fallen to Earth and
> been recovered.
>
> "The analysis has just started and no conclusive results (are) given
> until the measurements are detailed and analyzed," Kawaguchi told
> Spaceflight Now.
>
> "When we talk about the shape just from impression and not from a
> scientific point of view, the shape apparently looks like an object
> (with many) smaller objects united. And also apparently, a small
> (object) and some other objects are accreted with a larger one. These
> are not interpreted at all and definitely have to wait for detailed
study."
>
> Hayabusa will have to occasionally refine its position relative to the
> asteroid because the object's gravity is too weak to keep the craft in a
> stable stationary position.
>
> Controllers plan to order Hayabusa to close further toward Itokawa at
> the end of September, when more precise science activities are
> scheduled. Once in the "home position" under five miles from the
> asteroid, remote sensing observations will continue as the object
> completes one rotation about every 12 hours.
>
> A goal of the remote sensing phase will also serve to choose up to three
> sites that are scientifically interesting and safe enough to bring the
> fragile spaceship to the surface for sample retrieval passes beginning
> in November. During each approach, a 16-inch funnel aboard Hayabusa will
> make contact with the asteroid, followed by the firing of a small metal
> pellet into the rocky crust at hundreds of feet per second.
>
> Rubble and dust ejected from the high-speed impact will make their way
> through the funnel and into a chamber designed to carry the samples on
> the return trip to Earth and through the fiery re-entry into the
> atmosphere. Officials expect up to one gram - or two one-thousandths of
> a pound - of material will be gathered.
>
> It is expected that the ground team will eventually choose two sites for
> sample runs, leaving a third as a rehearsal to test the operation and
> feasibility of the plan.
>
> Also during the first pass, Hayabusa will deploy a tiny 1.3-pound rover
> known as MINERVA, which will leap, hop, and jump across the surface in
> the extreme low-gravity environment. MINERVA carries three stereo
> cameras for pictures, and a suite of six thermometers to measure
> temperatures.
>
> Hayabusa - formerly known as MUSES-C - was launched on May 9, 2003,
> aboard an M-5 rocket from Japan's Kagoshima launch site. The spacecraft
> flew past Earth a year later to receive a gravity boost that aimed
> Hayabusa toward this year's encounter with Itokawa.
>
> Time spent in the vicinity of asteroid Itokawa was reduced by a 2003
> solar flare that slightly damaged the ability of Hayabusa's two solar
> panels to produce electricity, which is vital to the operation of the
> craft's primary ion propulsion system. The degradation caused the four
> ion drive engines to produce less total thrust with less operating time,
> delaying arrival from mid-summer until now.
>
> Plans call for Hayabusa to depart Itokawa in early December to begin its
> trek back to Earth, culminating with a homecoming in June of 2007 by way
> of parachuted landing at Woomera in the Australian outback.
>
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Received on Wed 14 Sep 2005 08:45:44 PM PDT