The Japanese spacecraft Hayabusa evidently managed to land on asteroid Itokawa several days ago after all, according to this from the Japan Aerospace Exploration Agency:
“At the timepoint of Nov. 21, Hayabusa was judged not to have landed on the surface. According to the replayed data, however, it was confirmed that Hayabusa stayed on Itokawa by keeping contact with the surface for about 30 minutes after having softly bounced twice before settling. This can be verified by the data history of LRF and also by attitude control record…”
For more, you can read the complete JAXA statement here. The spacecraft is now being maneuvered for a second landing (and surface sampling) attempt. Note the shadow in this photograph, much more clearly visible than in the previous images of Itokawa from Hayabusa. There are people who shrug at this sort of thing, but to Centauri Dreams images like these are breathtaking. They remind us that a human presence has now encountered objects hitherto unexplored, the shape of technology defined on a surface untouched since the formation of the Solar System.
Image: Target marker with signatures (image taken at altitude of 32 meters). Credit: JAXA.
The space-borne infrared observatory AKARI, observed
asteroid Itokawa last month with its Infrared Camera.
The data will be used to refine estimates of sizes of
potentially hazardous asteroids in the future.
More at:
http://www.esa.int/esaSC/SEMJEVWZK5F_index_0.html
Info and links on an animated film about Hayabusa’s mission:
http://planetary.org/blog/article/00001241/
Are There Meteors Originated from Near Earth Asteroid (25143) Itokawa?
Authors: K. Ohtsuka, S. Abe, M. Abe, H. Yano, J. Watanabe
(Submitted on 19 Aug 2008)
Abstract: As a result of a survey of Itokawid meteors (i.e., meteors originated from Near Earth Asteroid (25143) Itokawa = 1998SF36), from among the multi-station optical meteor orbit data of ~15000 orbits, and applying the D-criteria, we could find five Itokawid meteor candidates.
We also analyzed corresponding mineral materials of the Itokawid candidates through their trajectory and atmospheric data. We conclude, on the basis of our investigation, that the fireball, MORP172, is the strongest Itokawid candidate.
Comments: 8 pages, 3 tables, 0 figure, accepted by ASP Conference Series Forthcoming Volume “International Science Symposium On Sample Returns From Solar System Minor Bodies – The First Hayabusa Symposium” (eds. Hajime Yano, Akira Fujiwara, Don Yeomans and Michael Zolensky), 20-24 October 2004, ISAS/JAXA, Sagamihara, Kanagawa, Japan
Subjects: Astrophysics (astro-ph)
Cite as: arXiv:0808.2671v1 [astro-ph]
Submission history
From: Takashi Ito [view email]
[v1] Tue, 19 Aug 2008 23:33:02 GMT (25kb)
http://arxiv.org/abs/0808.2671
Official Approval of Names on ITOKAWA by IAU March 3, 2009 (JST)
Japan Aerospace Exploration Agency (JAXA)
The Japan Aerospace Exploration Agency (JAXA) requested the International Astronomical Union (IAU) approve 14 names of craters andplaces on the surface of the asteroid “ITOKAWA,” where our Asteroid Explorer “HAYABUSA” carried out scientific observations.
The application was submitted under the theme of “place names concerning space development and asteroid science.”
On February 29, 2009 (Japan Standard Time,) the names were approved by the IAU, thus they can be used as official names. We thoroughly discussed the names with the IAU’s Working Group for Planetary System Nomenclature, and all our proposed names were accepted.
This was the first time that Japan requested the approval of such a large number of names for the surface of an asteroid and all of them were accepted at once. It was also the first time that such a number of Japanese names were christened on the surface of an asteroid. The names were decided in corporation with the University of Aizu, which studies the topology on the surface of the ITOKAWA based on observation data.
Reference:
Names of astronomical bodies and names of places on astronomical bodies
http://www.jaxa.jp/press/2009/03/20090303_itokawa_e.html#ref1
Table 1: Names on ITOKAWA and where they come from
http://www.jaxa.jp/press/2009/03/20090303_itokawa_e.html#ref2
The HAYABUSA flying to the ITOKAWA (Artist’s Concept)
Names of craters and places on ITOKAWA (Images were taken by the HAYABUSA)
http://www.jaxa.jp/press/2009/03/20090303_itokawa_e.html#ref3
Reference:
Asteroid “ITOKAWA”
http://www.jaxa.jp/press/2009/03/20090303_itokawa_e.html#ref4
This page URL:
http://www.jaxa.jp/press/2009/03/20090303_itokawa_e.html
Spitzer Observations of Spacecraft Target 162173 (1999 JU3)
Authors: H. Campins, J. P. Emery, M. Kelley, Y. Fernandez, J. Licandro, M. Delbo, A. Barucci, E. Dotto
(Submitted on 6 Aug 2009)
Abstract: Near-Earth asteroid 162173 (1999 JU3) is the primary target of the Hayabusa-2 sample return mission, and a potential target of the Marco Polo sample return mission. Earth-based studies of this object are fundamental to these missions.
We present a mid-infrared spectrum (5-38 microns) of 1999 JU3 obtained with NASA’s Spitzer Space Telescope in May 2008. These observations place new constraints on the surface properties of this asteroid. To fit our spectrum we used the near-Earth asteroid thermal model (NEATM) and the more complex thermophysical model (TPM). However, the position of the spin-pole, which is uncertain, is a crucial input parameter for constraining the thermal inertia with the TPM; hence, we consider two pole orientations. In the extreme case of an equatorial retrograde geometry we derive a lower limit to the thermal inertia of 150 J/m^2/K/s^0.5.
If we adopt the pole orientation of Abe et al. (2008a) our best-fit thermal model yields a value for the thermal inertia of 700+/-200 J/m^2/K/s^0.5 and even higher values are allowed by the uncertainty in the spectral shape due to the absolute flux calibration. The lower limit to the thermal inertia, which is unlikely but possible, would be consistent with a fine regolith similar to wthat is found for asteroid 433 Eros. However, the thermal inertia is expected to be higher, possibly similar to or greater than that on asteroid 25143 Itokawa.
Accurately determining the spin-pole of asteroid 162173 will narrow the range of possible values for its thermal inertia.
Comments: 4 pages, 2 figures; to be published as a Letter in Astronomy and Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
DOI: 10.1051/0004-6361/200912374
Cite as: arXiv:0908.0796v1 [astro-ph.EP]
Submission history
From: Yanga Fernandez [view email]
[v1] Thu, 6 Aug 2009 05:13:00 GMT (26kb)
http://arxiv.org/abs/0908.0796
The Hayabusa Spacecraft Asteroid Multi-Band Imaging Camera: AMICA
Authors: Masateru Ishiguro, Ryosuke Nakamura, David J. Tholen, Naru Hirata, Hirohide Demura, Etsuko Nemoto, Akiko M. Nakamura, Yuta Higuchi, Akito Sogame, Aya Yamamoto, Kohei Kitazato, Yasuhiro Yokota, Takashi Kubota, Tatsuaki Hashimoto, Jun Saito
(Submitted on 24 Dec 2009)
Abstract: The Hayabusa Spacecraft Asteroid Multiband Imaging Camera (AMICA) has acquired more than 1400 multispectral and high-resolution images of its target asteroid, 25143 Itokawa, since late August 2005.
In this paper, we summarize the design and performance of AMICA. In addition, we describe the calibration methods, assumptions, and models, based on measurements.
Major calibration steps include corrections for linearity and modeling and subtraction of bias, dark current, read-out smear, and pixel-to-pixel responsivity variations. AMICA v-band data were calibrated to radiance using in-flight stellar observations. The other band data were calibrated to reflectance by comparing them to ground-based observations to avoid the uncertainty of the solar irradiation in those bands.
We found that the AMICA signal was linear with respect to the input signal to an accuracy of << 1% when the signal level was < 3800 DN. We verified that the absolute radiance calibration of the AMICA v-band (0.55 micron) was accurate to 4% or less, the accuracy of the disk-integrated spectra with respect to the AMICA v-band was about 1%, and the pixel-to-pixel responsivity (flatfield) variation was 3% or less. The uncertainty in background zero-level was 5 DN.
From wide-band observations of star clusters, we found that the AMICA optics have an effective focal length of 120.80 \pm 0.03 mm, yielding a field-of-view (FOV) of 5.83 deg x 5.69 deg. The resulting geometric distortion model was accurate to within a third of a pixel.
We demonstrated an image-restoration technique using the point-spread functions of stars, and confirmed that the technique functions well in all loss-less images. An artifact not corrected by this calibration is scattered light associated with bright disks in the FOV.
Comments: 107 pages, 22 figures, 9 tables. will appear in Icarus
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:0912.4797v1 [astro-ph.EP]
Submission history
From: Masateru Ishiguro [view email]
[v1] Thu, 24 Dec 2009 05:47:32 GMT (1425kb)
http://arxiv.org/abs/0912.4797