Combining decades of theory, research, observation, and data collection, Dutch Astronomer Ewine van Dishhoeck and a team of international researchers have finally released a comprehensive, long-awaited guide to everything we currently know about the origin of water in space.
Published in the journal Astronomy & Astrophysics, the paper not only summarizes all of our existing knowledge about interstellar water, both inside and outside our own Milky Way galaxy but also provides a host of new information about how the chemical compound often deemed the most critical for life may end up on potentially habitable worlds.
“New planetary systems are likely to be born with sufficient water to become habitable,” the published paper states. “The Herschel data have shown that water gas and ice are commonly associated with star-forming regions, and that this conclusion is independent of “environment” or location in our Galaxy.”
Background: Where Does Water Come From?
Due to an abundance of water vapor in Earth’s atmosphere, ground-based telescopes have historically had a challenging time studying water outside our solar system. This issue restricts researchers and astronomers from determining how and where water is formed and how it ends up on a planet like our own.
This all changed in 2009 when the European Space Agency (ESA) launched the Herschel far-infrared space telescope. One of its primary missions was to hunt for and analyze water in space. Dubbed ‘Water In Star-forming regions with Herschel’ (WISH), the successful mission was brought to a planned close on April 29th, 2013, when, according to its ESA mission profile page, “the helium used to cool the focal plane of the scientific instruments was depleted.”
Since then, the readings gathered during its four years of operation have provided a treasure trove of data, with the recent press release announcing the paper’s publication pointing out how, “in recent years, dozens of scientific articles have been published based on Herschel’s water data.”
Those articles, the release notes, “have been combined and expanded with new insights,” forming the base of the recently published paper.
Analysis: The Origin of Water
The most compelling find detailed in the paper is how water starts as tiny particles of ice connected to interstellar dust before gathering to a planet during its accretion (formation) phase. This previously theoretical process was often opposed by theories stating that most planetary water was likely delivered by a series of comet strikes well after the planet had already formed. With this data, researchers now know different.
“Water is formed as ice on tiny dust particles in cold and tenuous interstellar clouds,” the paper’s release states. “When a cloud collapses into new stars and planets, this water is largely preserved and quickly anchored into pebble-sized dust particles.” It is these pebbles, the paper explains, that form the building blocks for things like new, potentially habitable planets.
Also significant to the search for potentially habitable worlds, the paper notes that based on their analysis of this critical planetary creation phase, “the researchers have calculated that most new solar systems are born with enough water to fill several thousand oceans.”
Outlook: The Origin of Water Is a Key Research Goal
It is this type of previously unavailable data, says one of the paper’s co-authors, Lars Kristensen from the University of Copenhagen, that will help with research being conducted at one of the few ground-based observatories sensitive enough to look for water in space, the ALMA telescopes in Chile.
“Thanks to Herschel’s legacy,” Kristensen says, “we can interpret the ALMA data much better.”
As for others hoping to build on the comprehensive data provided in this long-anticipated paper, the James Webb telescope, scheduled for launch around the end of October, is outfitted with the jointly developed NASA/ ESA Mid-InfraRed Instrument, also known as MIRI. And, as co-author Michiel Hogerheijde from the Leiden University and the University of Amsterdam explains, at least some of Webb’s future research will be guided by the data the paper has put together.
“Herschel has already shown that planet-forming disks are rich in water ice. With MIRI, we can now follow that trail into the regions where Earth-like planets are formed.”
Unfortunately, James Webb is in high demand, and no other space telescopes specifically designed for this type of research are currently planned until 2040. “There was a chance that a ‘water telescope’ would go into space around 2030,” van Dishoeck said in the release, “but that project was canceled.”
While a setback, van Dishoeck notes that the canceled 2030 mission provided an extra incentive for him and his team to publish the recently published overview. “In that way,” he states, “we have a collective memory for when a new mission comes along.”
In the end, the press release notes that the published article is expected to serve as a reference in this field of study for the next twenty years. However, van Dishoeck sounds like he may have had an even larger scope of time in mind when contemplating the ramifications of his team’s work.
“It’s fascinating to realize that when you drink a glass of water,” the Dutch astronomer said, “most of those molecules were made more than 4.5 billion years ago in the cloud from which our sun and the planets formed.”
Follow and connect with author Christopher Plain on Twitter:@plain_fiction