(C) Ratio of the after image divided by the before image. (B) After image acquired by the LROC NAC of the same area as image A (right after the crater formed). (A) Before image acquired by the LROC NAC (right before the crater formed). Before and after images acquired by the LROC NAC enabled scientists to locate the newly formed impact crater and study secondary surface changes. The Mini-RF instrument is operated in concert with the Arecibo Observatory to collect bistatic radar data of the lunar nearside from 2012 to 2015 the response for the floor of the south-polar permanent shadowed region in Cabeus crater is consistent with the presence of blocky, near-surface deposits of water ice ( Patterson et al., 2016).įIGURE B.1 An 18 m diameter crater that formed on the Moon on March 17, 2013, and was observed by Earth-based monitors. The abundance of rocks in ejecta blankets is well correlated with the age of the crater from ~100 kyr to ~1.5 Gyr ( Ghent et al., 2014), establishing a new “lithochronology” technique. Although most volcanism on the Moon appears to have ended 2 to 3 Gyr ago, observations by LROC suggest late stage activity persisted until <100 Myr ( Braden et al., 2014). The polar hydrogen distribution at both the north and south poles is asymmetric and mirrored, suggesting that true polar wander has occurred ( Siegler et al., 2016). These data, together with other data such as from the Lyman Alpha Mapping Project (LAMP) and temperatures measured by Lunar Diviner Radiometer ( Hayne et al., 2015), collectively suggest that a micron-thick layer of water ice is present in these regions. The Lunar Orbiter Laser Altimeter (LOLA) detected enhanced reflectivity nm in permanently shadowed regions at both the north and south poles ( Lucey et al., 2014). The orientation of these scarps is not random but rather consistent with a pattern expected from stresses introduced from solid body tides with Earth ( Watters et al., 2015). The high-resolution LROC images also revealed numerous small-scale tectonic features with pristine morphologies, indicating that they are likely still forming, most likely due to cooling of the interior. In addition to the craters themselves, >45,000 albedo marks (splotches) are observed that provide information regarding secondary cratering processes ( Robinson et al., 2015). The number of new craters shows that the size frequency distribution is steeper than expected based on models commonly used to date surfaces.
More than 220 new resolved impact craters were discovered as of March 2016 ( Figure B.1), having diameters of 1.4 to 43 m. This legacy data set will be used for decades of lunar exploration and science.Ī few of the key LRO science results from the extended mission are summarized below. An important legacy of the LRO mission is the vast amount of data made available to the scientific community, which is expected to be >900 TB by the end of 2018. LRO includes seven science experiments all remain healthy, except that the Miniature Radar Frequency (Mini-RF) transmitter ceased to function in December 2010 but still produces useful measurements as a receiver in a bi-static configuration (Earth-based assets transmit). Originally in a quasi-circular 50 km orbit, after 18 months of operation LRO was moved to a ~30 km × ~180 km orbit to conserve fuel all extended missions observations have been from the fuel-saving elliptical orbit. The Lunar Reconnaissance Orbiter (LRO) has been orbiting the Moon for nearly 7 years. Opportunity Rover During Extended Phase LUNAR RECONNAISSANCE ORBITER
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