Packed 7-bit ASCII, 12
fÍëWßËfDfÍëWßËfD
Since Markdown eats some of the characters, here's a hexdump:
$ xxd hello.ascii
0000000: 9197 66cd eb10 57df cb66 4420 ..f...W..fD
And yes, the trailing space is necessary.
Packed 7-bit ASCII is created by taking 8-bit ASCII (the normal kind), removeremoving the high zero bit from each byte, packing the remainder, and then padding it out with trailing zero bits.
According to this site, this character encoding is used by "a specific US MIL STD message header format", making it a real thing.