Start by heading to Parrot's website (1) and downloading the Asteroid 1.5 update to you computer (2). Then connect an empty, FAT32-formated USB drive to your machine (3) and place the downloaded file into the root directory (4). Don't put the file in a subfolder or the update may not take.
Make sure the Asteroid is powered off. Plug the USB drive into your Parrot Asteroid's USB port. We just used the USB pigtail that we normally use for audio playback. Additionally, make sure that any iPods or other USB drives have been disconnected.
Hit the home key to jump to the main menu, then use the control knob to select "Settings" (7). Select "Advanced settings" (8), then "Update" (9) and wait for the Asteroid to reboot itself. The unit will first check that the update file is where it expects it to be, then reboot yet again to install the firmware update (10).
Congratulations, you've just updated your firmware. Disconnect the USB drive with the update files and enjoy your Asteroid's new functions. One of the most noteworthy new features is smartphone tethering via USB or Bluetooth, a feature that finally makes the Asteroid's web-connected features useful to those of us without an extra wireless 3G/4G dongle lying about.