QT-RTG

The QT-RTG is a power generation item in Astroneer that supplies a constant stream of power. It is a smaller version of the RTG that is able to fit into a player's backpack.

Source
The QT-RTG may only be acquired from completing certain Missions (12 total) or found rarely on certain planets, either in EXO Dynamics Research Aids that require Astronium or specific wrecks.

Uses
QT-RTGs may be placed on the player's backpack or on platforms to provide a steady stream of power at all times. This allows players to constantly run a Portable Oxygenator, providing infinite oxygen away from a base's oxygen supply.

 •  A Medium Storage Silo full of QT-RTGs can create an incredibly dense power source that can easily power an Atmospheric Condenser, making Gas collection much easier.

Trivia

 * The QT-RTG was first shown on the March 12, 2021 SES_Dev Twitch stream.