The very basic building blocks of the Universe are no different than those of us: atoms and molecules. Sure, it takes bazillions of them to make a planet and countless gazillions to create a galaxy, but the molecules are the same.
Astrochemistry is an interdisciplinary field that catapulted out of the noise of radio astronomy’s robust childhood in the mid-1960s. Simply stated, it is the study of chemicals in space. (For those keeping score: we have cataloged over 180 so far .)
However, astrochemistry has its colorful beginnings in the work of English astronomer Sir William Huggins. Huggins and his Irish wife, Margaret, are the proud parents of astronomical spectroscopy. Their innovation to employ spectroscopy techniques on telescopes allowed this power couple to identify the elements in several stars and nebulae.
The Huggins’ brilliant and innocent discovery of cyanide gas in Halley’s Comet caused a panic in 1910 when the Earth passed right through Halley’s tail. It wasn’t until the advent of radio astronomy that the richness and diversity of the cosmic chemistry lab was truly realized.
Enter the Molecule Hunters
Chemists did not consider the hostile environment of interstellar space to be a decent chemistry lab. Molecules should not be able to assemble from a cold, near-vacuum of atoms, and if they did, they should be blasted apart by the radiation of nearby stars.
In 1968, our iconic 140-foot dish radio telescope in Green Bank, West Virginia changed everyone’s mind when astronomers used it to detect formaldehyde molecules in the center of our Galaxy. This telescope went on to spot several other organic molecules there and in the Orion Nebula.
With the need for a dedicated astrochemistry instrument, we built our 36-foot telescope on the dry slope of Kitt Peak in Arizona to collect the higher frequency radio waves known as millimeter waves, the channels to tune to for many more murmurs of molecules.
Since 1940, the boom periods of molecule detections in space always coincided with the big molecule-hunting telescopes coming on line. Astrochemists find an average of four new molecules every year and have cited the Green Bank Telescope in nearly 40% of new detections since 2004. The half-a-dozen or so other molecule-hunting telescopes divvy up the rest of the detection pie, but none has a piece so big as GBT’s.
Astrochemistry to Astrobiology
Of the five pre-biotic molecules found in space to date, four of them were detected by the GBT. They include the pre-cursors to the pre-biotic molecule adenine needed to construct DNA and amino acids. They were all found in the center of our Galaxy where devastating radiation from powerful stars should have blown them to bits.
However, radio telescopes have shown that these molecules are apparently ubiquitous throughout our Galaxy, hitching up on passing debris, because on several meteorites examined to date, scientists have detected adenine and the amino acids that build proteins!
Up to 10,000 tons of meteorite material enters the Earth’s atmosphere every day. If you figure that the other planets and moons in our Solar System (and the nearly 700 other systems confirmed so far) are also plowing into an equivalent scaled volume of chemically-rich material, then you could find it difficult to accept that Earth’s living systems are alone in our Galaxy.
The systematic hunt for life elsewhere in the Galaxy is called astrobiology. This field grew out of NASA’s Exobiology Program of the 1960s, spearheaded by Professor Carl Sagan. Most memorable of NASA’s early exobiology projects were the Mars Viking missions that included soil sampling experiments that controversially did-but-didn’t find chemical signs of life on Mars.
In recent years, astrobiology has become a mainstay of NASA missions and science, and although signs of extraterrestrial lifeforms still remain to been found, their chemical building blocks certainly have.
As ALMA’s molecule-hunting prowess comes online, we expect to be overwhelmed by high-resolution spectral lines we cannot identify. Our astrochemistry labs at the University of Virginia and elsewhere have been preparing for ALMA by identifying the individual fingerprints of complex Earth-based molecules they create in their test chambers.
The line between astrobiology and astrochemistry fades with each new discovery made by the GBT and ALMA, and radio telescopes become more a tool of science than of strictly astronomy.