Final answer:
A vessel may not respond due to radio system malfunctions or submarine operations. Submarines use ELF signals for communication, as these penetrate water, but can be affected by shorter wavelengths. Cosmic interference, such as from solar flares or cellular signals, can also interrupt communications.
Step-by-step explanation:
A vessel might not respond for a variety of reasons, such as a radio system malfunction or submarine operations. A radio system malfunction could be due to equipment failure or damage, preventing proper communication with the vessel. This could be a simple case of technical issues or more complex problems like a hardware breakdown.
In the case of submarine operations, matters are different. Submarines typically use extremely low frequency (ELF) signals to communicate because these very long wavelength radio waves can penetrate through seawater to greater depths. Shorter wavelengths, which are commonly used in surface communications, cannot reach submerged submarines effectively.
The concept of cosmic interference pertains to situations where extraterrestrial or space-related phenomena impact communications. This could be related to solar flares, cosmic radiation, or other forms of spillover from terrestrial communications that affect radio frequencies. For example, interference from cellular phone signals could potentially drown out signals used for delicate operations like radio astronomy or other scientific pursuits.