Following default instructions, I was able to put Ubuntu 16 on a Chromebook in developer mode. But the current LTS (Longer Term Support) release for ROS (Robot Operating System) is their "M" or Melodic Morenia release whose corresponding Ubuntu LTS is 18. (Bionic Beaver)

As of this writing, Ubuntu 18 is not officially supported for Crouton. It's not explicitly forbidden, but it does come with a warning: "May work with some effort." I didn't know exactly what the problem might be, but given how easy it is to erase and restart on a Chromebook I decided to try it and see what happens.

It failed failed with a hash sum failure during download. This wasn't the kind of failure I thought might occur with an unsupported build, download hash sum failure seems more like a flawed or compromised download server. I didn't understand enough about the underlying infrastructure to know what went wrong, never mind fixing it. So in an attempt to tackle a smaller problem with a smaller surface area, I backed off to the minimalist "cli-extra" install of Bionic which skips graphical user interface components. This path succeeded without errors, and I now have a command line interface that reported itself to be Ubuntu 18 Bionic.

As a quick test to see if hardware is visible to software running inside this environment, I plugged in a USB to serial adapter. I was happy to see dmesg reported the device was visible and accessible via /dev/ttyUSB0. Curiously, the owner showed up as serial group instead of the usual dialout I see on Ubuntu installations.

A visible serial peripheral was promising enough for me to proceed and install ROS Melodic. I thought I'd try installation with Python 3 as the Python executable, but that went awry. I then repeated installation with the default Python 2. Since I have no GUI, I installed the ros-melodic-ros-base package. Its installation completed with no errors, allowing me to poke around and see how ROS works in this environment.