Friday 8 November 2013

Another brief update on #GOCE, 8 Nov 2013

The average orbit of GOCE is now below 172 km altitude, with perigee below 170 km. It is hence approaching the critical value of 150 km.

Due to the effects of several recent solar outbursts on the atmosphere, drag levels went up and fluctuated over the past 1.5 days (see ESA's blog here and the diagram below). This makes forecasting difficult. Forecasts at different times today varied as a result, but they all are somewhat earlier in time than they were yesterday.

The forecast at the moment of writing (SatEvo prediction on a 1-day SatAna arc up to Nov 8.55 UT) is for a 1-day window centered on Nov 10.7 UT. With the same caveat as in my previous posts: this forecast assumes GOCE will keep its drag-reducing attitude up to re-entry, which is by no means certain.

USSTRATCOM has issued two first TIP-bulletins for GOCE, yesterday and today. The last of these forecasts is re-entry at Nov 11.12 UT, +/- 48 hours.

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