Initial report of Hayabusa2 laser altimeter (LIDAR)
Abstract
The laser altimeter called LIDAR (Light Detection and Ranging) aboard Hayabusa2 asteroid explorer is an instrument for spacecraft navigation and topographic mapping of the asteroid 162173 Ryugu.
The spacecraft usually stays at a position 20 km over the asteroid which we call the "home position". The global mapping can be done even at the home position thanks to the rotation of the asteroid. Two lower altitude operations and one tour operation are scheduled before the first touchdown to the asteroid for the determination of the landing site. In the science mapping observations twice in a week, laser ranging is conducted for about eight hours with the laser repetition rate of 1 Hz, while in other days of the week and the rest of the science mapping observations, the repetition rate is set as low as 1/32 Hz for spacecraft navigation. Among two day scientific observations in a week, spacecraft scanning operation is done once and most of the asteroid surface except for polar regions is ranged which are mostly invisible from above the equator region. The laser ranging with LIDAR started on 26th June, 2018, which is one day before arrival at the home position. At the first spacecraft scanning on 11th July, 2018, the LIDAR successfully determined the shape of the asteroid which is consistent with a shape model by camera data. Orbit estimation of the spacecraft can be done more precisely by fitting footprints of the LIDAR to the shape model of the asteroid, which is beneficial to the data analysis of other scientific instruments. The transmitted energy and received power of the laser pulses are available to estimate the surface reflectance (albedo) at 1 micrometer wavelength of the laser. From the home position, the received power is sometimes not strong enough for the derivation of the albedo. Data during the low-altitude mapping will be beneficially used for more precise estimation of the surface albedo. Also, the LIDAR is equipped with the dust counting mode for the detection of levitating dust particles above the asteroid. The observation for detecting dust particles is scheduled for ten minutes in a week.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.P22A..07N
- Keywords:
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- 6040 Origin and evolution;
- PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6055 Surfaces;
- PLANETARY SCIENCES: COMETS AND SMALL BODIESDE: 6205 Asteroids;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTSDE: 6207 Comparative planetology;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS