1. Activate towers ASAP and reset the vault (If they exist). This will help reduce the planetary issues of radiation, heat, or cold (and let you wander outside the Nomad much longer).
2. EOS - Explore and clear the old sites, reset the towers and vault, sort out the murder mission, establish an outpost, save the work crew. DO NOT try to explore the rest of the planet for memory triggers or rare minerals YET. The radiation will go away in time. Go back to Nexus and continue the main story line - save a planet or two. You'll be called back eventually to EOS to clear the rest (with no radiation to worry about.)
3. On PC. To get back to the Tempest quickly from anywhere on the planet, just hop into the Nomad and hold down T. Saves a lot of time (and gets you off H-047c).