  The problem of the re-entry predictions of GOCE has been deeply investigated
in the literature, due to the large amount of data, mainly radar and GPS,
available until re-entry. The accurate GPS and attitude measurements are used
to compute a precise reference orbit for the three weeks of decay, and to
extrapolate the ballistic coefficient evolution of the object. In previous
works, the capabilities of radar-based solutions for the re-entry predictions
of GOCE and of similar objects were investigated, focusing on the german TIRA
radar. In this work we have performed additional analysis, focusing on the
northern european radar EISCAT-UHF, located in Troms\o, Norway. This sensor,
conceived for atmospheric studies, has recently been considered for space
debris applications. Due to its limited tracking capabilities, we are
interested in testing its effectiveness in supporting re-entry predictions. We
have simulated reliable re-entry prediction scenarios, with different
availability of data from EISCAT and TIRA. The main conclusion is that,
provided a suitable amount of observations, EISCAT-based re-entry predictions
are comparable to TIRA-based, but also to GPS and TLE-based, corresponding
ones. In general, EISCAT is not able to determine an orbit with the same
accuracy of TIRA, but the results are equivalent in terms of re-entry
predictions, if we consider the relevant parameters involved and their effects
on the re-entry time. What is very important is the difficulty in predicting
atmospheric and attitude significant variations in between the current epoch
and the actual re-entry. Thus, it is not easy to keep the accuracy of
predictions much lower than 10% of the residual lifetime, apart from cases with
constant area to mass ratio, and low atmospheric variations with respect to the
models. An experiment with real data is presented for the object 2012-006K,
with consistent results.
