Thursday, 7 May 2015

[UPDATED] Progress M-27M re-entry predictions

[predictionlast updated 7 May 18:30 UT]
[update 8 may 2015: NEW post  about the re-entry HERE]

I am providing occasional estimates for the uncontrolled re-entry of Progress M-27M on my Twitter feed today. Likewise, several other people are providing estimates, of which I would want to recommend those by Ted Molczan on the Seesat mailing list. You will note that the re-entry predictions will vary from source to source!

My current estimate is for re-entry to occur:

between 17 and 22 UT on May 7
between 21:10 and 01:30 UT  May 7-8

between 00:00 and 04:00 UT May 8

(estimate update issued 7 May, 18:30 UT based on elsets up to epoch 15127.69084936 processed with Alan Pickup's SatAna and SatEvo software).

Within this window, the slightly more likely moments are around and just after perigee passage, i.e. the tracks over the Pacific in this case.

The estimate may still change as new orbits are released. Previous released elsets initially strongly pushed the estimated re-entry time back from early May 8 to late May 7, as the result of solar activity yesterday and the resulting effects on the outer Earth atmosphere. As a result, my earlier estimate of this morning (May 7) overestimated the decay rate. With the new orbital update from epoch 15127.50860911 and onwards things are settling towards more realistic values, with a trend of slightly moving the decay window to a later time.

Above is a rough map of where the re-entry might occur, based on current uncertainties.

For updates, keep an eye on my Twitter feed.

[update: final re-entry results have been posted in a new post here]

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