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A NASA team scanned these terrestrial rock samples, all measuring two to four inches in diameter, to investigate possibilities for future in-space use of non-destructive evaluation techniques. The two rock samples on the bottom are from Earth’s newest volcanic island in the Kingdom of Tonga; the sample on the upper left from kilometers deep contains large green olivine crystals and came from Oahu in Hawaii. The sample on the upper right is a 3.7-million-year old impact melt breccia from the Elgygytgyn impact crater in Siberia. Credit: NASA/W. Hrybyk

Polymer synthesis, spectroscopic properties and self-assembly. a Synthesis of the perylene-bearing diblock terpolymer PEG43-b-P(NIPAM21-co-PDMI9). b Normalized absorption (solid lines) and fluorescence spectra (dashed lines) of the amine-reactive perylene derivative PDMI-PFP (red) and PEG43-b-P(NIPAM21-co-PDMI9) (blue) in THF. c TEM image of spherical aggregates formed by PEG43-b-P(NIPAM21-co-PDMI9) in a dilute THF solution (0.1 mg mL−1). Scale bar, 100 nm. d Schematic representation depicting the solvent-switch method used to induce self-assembly of PEG43-b-P(NIPAM21-co-PDMI9). e Schematic representations, average major axis lengths, aspect ratios, and TEM images of resulting self-assembled structures formed at different THF content...

In the beginning, there were chemicals. Credit: Illustration by Max Englund

These illustrations represent different levels of adaptive complexity we might imagine when thinking about aliens. (a) A simple replicating molecule, with no apparent design. This may or may not undergo natural selection. (b) An incredibly simple, cell-like entity. Even something this simple has sufficient contrivance of parts that it must undergo natural selection. (c) An alien with many intricate parts working together is likely to have undergone major transitions. Credit: Helen S. Cooper