Now that's WiFi!

Lunar probe transmits 461 gigabytes of data per day home. [Link]

As the first high data rate K-band transmitter to fly on a NASA spacecraft, the 13-inch-long tube, called a Traveling Wave Tube Amplifier, is making it possible for NASA scientists to receive massive amounts of images and data about the moon's surface and environment.
The amplifier was built by L-3 Communications Electron Technologies in conjunction with NASA's Glenn Research Center. The device uses electrodes in a vacuum tube to amplify microwave signals to high power. It's ideal for sending large amounts of data over a long distance because it provides more power and more efficiency than its alternative, the transistor amplifier, NASA stated.
A traveling wave tube is needed for high frequency and high power applications such as deep space communications because of its higher power capability and efficiency when compared to solid-state devices, NASA stated. The amplifier uses a new waveguide for input and output that adds strength to withstand mechanical shock and vibrations for enhanced reliability while traveling in the harsh environment of space.

I love that it uses a vacuum tube. How retro.