Multiple choice

When returning to the earth, spacecrafts have a communication blackout, the reason for this is

  1. the returning spacecraft is doing so against the force of gravity which interferes with the radio waves

  2. during the re-entry period the density of the plasma generated by the intense frictional heat is so high that the operational, frequencies used for communication become less than the plasma cut-off frequency resulting a total blackout

  3. stellar X-rays attract and absorb the sound waves

  4. the sounds created by the whirring of the mechanism of the spacecraft renders the sounds inaudible
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

During re-entry, the spacecraft creates a layer of ionized gas (plasma) due to extreme friction. This plasma layer blocks radio waves, causing a temporary communication blackout.

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