the first 700 million years of Earth history, the competing effects of magnetic shielding versus solar ion collection, and bounds on the detection level of a geodynamo imposed by the presence of external fields. We also discuss the prospects for constraining Hadean-Paleoarchean magnetic field strength using paleointensity analyses of zircons.'
address:
- 'Department of Earth and Environmental Sciences, University of Rochester, Rochester, New York, 14627, USA'
- 'Department of Physics and Astronomy, University of Rochester, Rochester, New York, 14627, USA'
author:
- 'John A. Tarduno'
- 'Eric G. Blackman'
- 'Eric E. Mamajek'
bibliography:
- 'tarduno2\_biblio.bib'
title: 'Detecting the oldest geodynamo and attendant shielding from the solar wind: Implications for habitability'
---

Geodynamo,Early Earth ,Solar Wind ,Atmospheric Loss ,Habitability

Introduction
============

The onset and nature of the geomagnetic field is important for understanding the evolution of the core, atmosphere and life on Earth. For the earliest Earth, the dynamo was powered thermally, so dynamo startup provides information on core heat flow and lower mantle conditions. A common posit is that the lack of magnetic shielding of cosmic radiation is inconsistent with the development of life, but it is clear that an atmosphere and ocean layer can provide some protection. The 