Earth biochemistry relies on DNA as the information-carrying polymer and water as the chemistry-facilitating solvent. Life on other planets, however, could leverage very different chemistry. This grant supports work by Sara Seager, Professor of Planetary Science, Physics, and Aeronautical and Astronautical Engineering at the Massachusetts Institute of Technology, that will explore an alternative to Earth biochemistry. The proposed research focuses on identifying a DNA-like molecule that is functional in concentrated sulfuric acid (CSA), the primary component of Venus’ atmosphere and a water-alternative solvent found on many planets in our galaxy.   There are several steps to establishing that a DNA-like molecule can function in CSA, and Professor Seager is tackling what is perhaps the core challenge: identifying components of a DNA-analog molecule that are structurally stable and appropriately reactive in CSA, focusing on the three primary molecular components of DNA: nucleic acid bases, so-called ‘linker’ molecules, and a ‘molecular backbone’ structure. Her project is divided into four tasks. In Task 1 Seager and her researcher team will determine the CSA reactivity of the nucleic acid bases found in DNA/RNA. While Seager has demonstrated that the core structures of these canonical bases are CSA-stable, it’s not yet known whether the bases can bond with one another in CSA; something required to form a DNA-like molecule.   Excess protons found in CSA (or in any acid) may interfere with the hydrogen bonding that holds two bases together in a DNA molecule, making base-pairing with these canonical bases impossible in CSA. Accordingly, in Task 2 the researcher team will test the CSA stability and reactivity of ‘alternative’ nucleic acid bases that do not rely on hydrogen bonding for base-pairing. In Task 3, the researchers will develop a list of linker and backbone molecule candidates that promise to be stable in CSA and in Task 4 these candidates will be subjected to CSA stability/reactivity testing.   Establishing that a replicating, information-bearing molecule can exist in CSA goes a long way to establishing CSA as a solvent that can host life. Such a finding would significantly impact exoplanet research, expand the number of planets regarded as habitable, and inform planned and proposed missions to Venus aimed at searching for signs of extraterrestrial life.