The surface temperature of Europa

Abstract

Previous estimates of the annual mean surface temperature of Jupiter's moon, Europa, neglected the effect of the eccentricity of Jupiter's orbit around the Sun, the effect of the emissivity and heat capacity of Europa's ice, the effect of the eclipse of Europa (i.e., the relative time that Europa is within the shadow of Jupiter), the effect of Jupiter's radiation, and the effect of Europa's internal heating. Other studies concentrated on the diurnal cycle but neglected some of the above factors. In addition, to our knowledge, the seasonal cycle of the surface temperature of Europa was not estimated. Here we systematically estimate the diurnal, seasonal and annual mean surface temperature of Europa, when Europa's obliquity, emissivity, heat capacity, and eclipse, as well as Jupiter's radiation, internal heating, and eccentricity, are all taken into account. For a typical internal heating rate of 0.05 , the equator, pole, and the global and mean annual mean surface temperatures are 96 K, 46 K, and 90 K, respectively. We found that the temperature at the high latitudes is significantly affected by the internal heating, especially during the winter solstice, suggesting that measurements of high latitude surface temperatures can be used to constrain the internal heating. We also estimate the incoming solar radiation to Enceladus, the moon of Saturn.

Dynamic Europa ocean shows transient Taylor columns and convection driven by ice melting and salinity

“…In addition, note several interesting features. First, surprisingly, the coldest water is at low latitudes, despite the much warmer low-latitude ice surface temperature 26,27 , in contradiction to the findings of previous studies of Europa's ocean 2,3 . This is a result of melting of the icy shell at the poles and freezing at the equator, accompanied by an efficient ocean meridional heat exchange 28 : The freezing leads to brine rejection and thus to salty dense water sinking at the equator, carrying down the cold and salty surface water as seen in Fig.…”

“…Europa's icy shell is represented using the MITgcm "shelf-ice" package 23 that enables the calculation of the ocean-ice freshwater and heat fluxes based on the surface ice temperature, ice thickness, and ocean temperature and salinity 23 . The forcing ice surface temperature was taken from 27 . Ice flow and dynamical ice thickness are not included in the shelf-ice package, but, as demonstrated above based on 28 , the ice thickness can be assumed uniform due to the efficient meridional heat flux of the ocean (Fig.…”

Ions Transport in Electrochemical Energy Storage Devices at Low Temperatures

“…Moreover, the current EES devices still cannot meet the application requirements on the surface of some satellites, such as Europa's surface which has a temperature of −170 °C. [5] Therefore, the development of low-temperature EES devices that can work at as low as the possible operating temperature is a long-term and challenging goal. 3) Further enhancing the low-temperature electrochemical performance: Researchers have been pursuing as low as possible operating temperature for EES devices, but ignored the more important task, that is, to improve the charge storage characteristics of devices at low temperatures, especially the energy density.…”

“…Moreover, the current EES devices still cannot meet the application requirements on the surface of some satellites, such as Europa's surface which has a temperature of −170 °C. [ 5 ] Therefore, the development of low‐temperature EES devices that can work at as low as the possible operating temperature is a long‐term and challenging goal.…”

“…For example, the average temperature on Mars can reach −55 °C, [ 4 ] and the average temperature on the surface of Europa is approximately −170 °C. [ 5 ] Accordingly, EES devices that will be used in outer space probes may have to face the extremely cold environment. Unfortunately, conventional EES devices almost cannot work in such cold environment.…”