Elsevier

Planetary and Space Science

Volume 85, 1 September 2013, Pages 293-298
Planetary and Space Science

High-resolution Vesta Low Altitude Mapping Orbit Atlas derived from Dawn Framing Camera images

https://doi.org/10.1016/j.pss.2013.06.024 Get rights and content

Highlights

  • The highest resolution mosaic of Vesta was created using camera data from the Low Altitude Mapping Orbit.

  • The highest resolution atlas of Vesta was created.

  • The nomenclature for additional surface features was approved by the IAU.

Abstract

The Dawn Framing Camera (FC) acquired close to 10,000 clear filter images of Vesta with a resolution of about 20 m/pixel during the Low Altitude Mapping Orbit (LAMO) between December 2011 and April 2012. We ortho-rectified these images and produced a global high-resolution uncontrolled mosaic of Vesta. This global mosaic is the baseline for a high-resolution Vesta atlas that consists of 30 tiles mapped at a scale between 1:200,000 and 1:225,180. The nomenclature used in this atlas was proposed by the Dawn team and was approved by the International Astronomical Union (IAU). The whole atlas is available to the public through the Dawn GIS web page [http://dawn_gis.dlr.de/atlas ].

Introduction

The Dawn mission has mapped Vesta from three different orbital heights during Survey orbit (2700 km altitude), HAMO (High Altitude Mapping Orbit, 700 km altitude), and LAMO (Low Altitude Mapping Orbit, 210 km altitude) (Russell and Raymond, 2011). The Dawn mission is equipped with a framing camera [FC (Sierks et al., 2011)] which has one clear filter and seven band pass filters. Clear filter images which were taken during HAMO were used to produce a global mosaic of the illuminated part of Vesta with a resolution of 70 m/pixel and a 15-tile atlas at a scale of 1:500,000 (Roatsch et al., 2012). The FC took about 10,000 clear filter images at low altitudes in LAMO which allowed us to produce a global mosaic of Vesta with a resolution of 20 m/pixel and a 30-tile atlas. This LAMO atlas is a higher-resolution supplementary atlas to the known HAMO atlas (Roatsch et al., 2012), the 15-tile atlas will still be used for geological and mineralogical mapping (e.g. Blewett et al., 2012, Williams et al., 2012). The LAMO mission phase occurred during Northern winter which kept the north pole region in darkness; only 84% of the surface was illuminated, as shown in Fig. 1, Fig. 2. The color codes represent the best geometric resolution of the acquired images at the respective surface position. This includes images which were taken with high incidence angles (between 70° and 90°); good illumination (incidence angle<70°) was only available for 66.8% of the surface.

Details of the image processing will be described in Section 2. Section 3 summarizes the high-level cartographic work that produced our high-resolution atlas, which consists of 30 map tiles of different regions of Vesta. Three examples of these map tiles are shown.

Section snippets

Data processing

The image data returned from the spacecraft are distributed inside the Dawn team in PDS (Planetary Data System) format [http://pds.jpl.nasa.gov ]. The first step of the image processing pipeline is the conversion to VICAR (Video Image Communication and Retrieval) format [http://rushmore.jpl.nasa.gov/vicar.html ] followed by the radiometric calibration of the images.

The next step of the processing chain deals with the photogrammetric image processing towards a global orthoimage mosaic. LAMO images

Vesta map tiles

The Vesta atlas consists of 30 map tiles whereof one map tile (Av-L-1) is missing since there are no LAMO data in the North polar area. The tiling scheme conforms to those proposed by Greeley and Batson (1990) and is used e.g., for mapping Mars in a scale of 1:5,000,000. A map scale of about 1:200,000 guarantees a mapping at the highest available Dawn FC resolution (LAMO) and results in an acceptable printing scale for the hardcopy map of 10 pixel/mm. The exact scale of all map tiles is given in

Outlook

The Dawn spacecraft is now en-route to asteroid Ceres and will arrive there in early 2015. The planned tour contains again a HAMO and a LAMO phase which will allow us again to calculate a controlled HAMO atlas and an uncontrolled LAMO atlas.

Acknowledgments

The authors gratefully acknowledge helpful discussions with J. Blue (USGS) about the proposed nomenclature for Vesta features and for reviewing the Vesta LAMO atlas.

References (11)

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