One potentially helpful strategy for identifying passive constructions does not rely on verb forms. While it is the case the prototypical passive consists of a form of werden combined with a past participle and can therefore be recognised as such just by examining the forms, there are some verbs where the past participle is identical to the infinitive:
werden + infinitive, active:
Manx wird diese Heldeny schnell wieder vergessen.
Eine Antennex wird die Signaley empfangen.
werden + past participle, passive:
Diese Heldeny werden schnell wieder vergessen.
Die Signaley werden von einer Antennex empfangen.
What allows these sentences to be interpreted unambiguously is knowledge about what complements a verb takes and what semantic roles x, y, … these complements fill. For instance, vergessen and empfangen are transitive verbs: They take a subject and an accusative object, with the object expressing what is being forgotten or received (the role indicated by y) and the subject expressing who is doing the forgetting or receiving (the role indicated by x).
The sentences under 1. are congruent with these expectations. However, those under 2. show a divergence: There is no object, and the subject expresses what is being forgotten or received (the role indicated by y, expressed by an object in the sentences under 1.). The role x is unspecified in one case and specified by an adverbial governed by von in the other.
It is therefore possible to identify a passive without looking at verb forms at all, just going by what complements there are and semantic role they are linked with. This strategy comes in handy for interpreting the many constructions that behave similarly to a passive:
Ein solches Unglücky lässt sich nicht leicht vergessen.
Die Signaley waren kaum zu empfangen.
Die Signaley waren kaum empfangbar.
die von der Antennex empfangenen Signaley
Wir haben das Gebäudey von Expertenx vermessen lassen.
In all these constructions, the subject fills the same semantic role y as the object of a corresponding active clause. (The last example is slightly more difficult, as the subject of vermessen is realised as the accusative object of lassen.)
This strategy can be applied to your examples. For instance:
(1) 21:42 Uhr wird sichy der Überschall-Fallschirmx entfalten und (2) der Hitzeschutzschildy [wird] abgeworfen.
The first sentence must be active since the subject is doing the unfurling and the object is being unfurled (even if subject and object, the verb being used reflexively, in this instance denote the same thing; if this problematic, think die Sonde wird den Schirm entfalten instead). The second sentence must be passive since there is no object and Hitzeschutzschild has the role y, i.e. is what is being discarded, not x, i.e. what is doing the discarding.