Today history has been made

No it was today, yesterday they launched the lander, but it came in too fast and bounced off the comet, they then had to wait until today for the landing point on the comet to come back around into view so they could land it properly.

Ask the engineers

Ask the scientificly illiterate marketers that oversold the idea.

Waterproof books are possible. We just need a book and a ton of waterproof coating. Hoverboards aren't as possible, however.