کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6429914 | 1634772 | 2013 | 5 صفحه PDF | دانلود رایگان |
- The surface temperature over an active chaos region can be as high as â¼200 K.
- No signs of activity were detected at Thera Macula by the Galileo PPR instrument.
- The presence of a near-surface insulating layer can reduce the thermal signature.
- More sensitive instruments can detect chaos activity despite insulating layer.
A recent study by Schmidt et al. (2011) suggests that Thera Macula, one of the “chaos regions” on Europa, may be actively forming over a large liquid water lens. Such a process could conceivably produce a thermal anomaly detectable by a future Europa orbiter or flyby mission, allowing for a direct verification of this finding. Here, we present a set of models that quantitatively assess the surface and subsurface temperatures associated with an actively resurfacing chaos region using constraints from Thera Macula. The results of this numerical study suggest that the surface temperature over an active chaos region can be as high as â¼200K. However, low-resolution Galileo Photo-Polarimeter Radiometer (PPR) observations indicate temperatures below 120 K over Thera Macula. This suggests that Thera Macula is not currently active unless an insulating layer of at least a few centimeters in thickness is present, or activity is confined to small regions, reducing the overall intensity of the thermal signature. Alternatively, Thera may have been cooling for at least 10-100 yr and still contain a subsurface lake, which can take â¼300,000 yr to crystallize. According to the present study, a more sensitive instrument capable of detecting anomalies â¼5 K above ambient could detect activity at Thera Macula even if an insulating layer of â¼50 cm is present.
Journal: Earth and Planetary Science Letters - Volume 384, 15 December 2013, Pages 37-41