NASA discovers ancient ocean on Asteroid Ceres

Via the AGU: WASHINGTON D.C. — Minerals containing water are widespread on Ceres, suggesting the dwarf planet may have had a global ocean in the past. What became of that ocean? Could Ceres still have liquid today? Two new studies from NASA’s Dawn mission shed light on these questions.

In one study, the Dawn team found Ceres’ crust is a mixture of ice, salts and hydrated materials that were subjected to past and possibly recent geologic activity, and this crust represents most of that ancient ocean. The second study builds off the first and suggests there is a softer, easily deformable layer beneath Ceres’ rigid surface crust, which could be the signature of residual liquid left over from the ocean, too.

“More and more, we are learning that Ceres is a complex, dynamic world that may have hosted a lot of liquid water in the past, and may still have some underground,” said Julie Castillo-Rogez, Dawn project scientist and co-author of the studies, based at NASA’s Jet Propulsion Laboratory, Pasadena, California.

This animation shows Ceres as seen by NASA’s Dawn spacecraft from its high-altitude mapping orbit at 913 miles (1,470 kilometers) above the surface. The colorful map overlaid at right shows variations in Ceres’ gravity field measured by Dawn, and gives scientists hints about the dwarf planet’s internal structure. Red colors indicate more positive values, corresponding to a stronger gravitational pull than expected, compared to scientists’ pre-Dawn model of Ceres’ internal structure; blue colors indicate more negative values, corresponding to a weaker gravitational pull. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

What’s inside Ceres?

Landing on Ceres to investigate its interior would be technically challenging and would risk contaminating the dwarf planet. Instead, scientists use Dawn’s observations in orbit to measure Ceres’ gravity, to estimate its composition and interior structure.

The first of the two studies, led by Anton Ermakov, a postdoctoral researcher at JPL, used shape and gravity data measurements from the Dawn mission to determine the internal structure and composition of Ceres. The measurements came from observing the spacecraft’s motions with NASA’s Deep Space Network to track small changes in the spacecraft’s orbit. This study is accepted for publication in the Journal of Geophysical Research: Planets, a journal of the American Geophysical Union.

Ermakov and his colleagues’ research supports the possibility that Ceres is geologically active – if not now, then it may have been in the recent past. Three craters – Occator, Kerwan and Yalode – and Ceres’ solitary tall mountain, Ahuna Mons, are all associated with gravity anomalies. This means discrepancies between the scientists’ models of Ceres’ gravity and what Dawn observed in these four locations can be associated with subsurface structures.

“Ceres has an abundance of gravity anomalies associated with outstanding geologic features,” Ermakov said. In the cases of Ahuna Mons and Occator, the anomalies can be used to better understand the origin of these features, which are believed to be different expressions of cryovolcanism.

The study found the crust’s density to be relatively low, closer to that of ice than rocks. However, a study by Dawn guest investigator Michael Bland of the U.S. Geological Survey indicated that ice is too soft to be the dominant component of Ceres’ strong crust. So, how can Ceres’ crust be as light as ice in terms of density, but simultaneously much stronger? To answer this question, another team modeled how Ceres’ surface evolved with time.

A ‘fossil’ ocean at Ceres

The second study, led by Roger Fu at Harvard University in Cambridge, Massachusetts, investigated the strength and composition of Ceres’ crust and deeper interior by studying the dwarf planet’s topography. This study is published in Earth and Planetary Science Letters.

By studying how topography evolves on a planetary body, scientists can understand the composition of its interior. A strong, rock-dominated crust can remain unchanged over the 4.5-billion-year-old age of the solar system, while a weak crust rich in ices and salts would deform over that time.

By modeling how Ceres’ crust flows, Fu and colleagues found it is likely a mixture of ice, salts, rock and an additional component believed to be clathrate hydrate. A clathrate hydrate is a cage of water molecules surrounding a gas molecule. This structure is 100 to 1,000 times stronger than water ice, despite having nearly the same density.

The researchers believe Ceres once had more pronounced surface features, but they have smoothed out over time. This type of flattening of mountains and valleys requires a high-strength crust resting on a more deformable layer, which Fu and colleagues interpret to contain a little bit of liquid.

The team thinks most of Ceres’ ancient ocean is now frozen and bound up in the crust, remaining in the form of ice, clathrate hydrates and salts. It has mostly been that way for more than 4 billion years. But if there is residual liquid underneath, that ocean is not yet entirely frozen. This is consistent with several thermal evolution models of Ceres published prior to Dawn’s arrival there, supporting the idea that Ceres’ deeper interior contains liquid left over from its ancient ocean.

###

Advertisements

28 thoughts on “NASA discovers ancient ocean on Asteroid Ceres

  1. There is a great deal we have yet to discover and learn about the solar system and its formation.

    The recent data on Pluto is similarly intriguing, such as the mountain range found at the equator which is thought to be only around 100 million years old. Since Pluto is not pulled by gravitational forces, as are some of the moons of Jupiter and Saturn, there is no obvious power source for such recent geological process.

    • The image you supply would make one doubt that gravity anomalies could be used to tell where the oceans are.

      Here’s another image showing the anomalies in the vicinity of Antarctica. The accompanying description demonstrates that the gravity measurements agree with the known structure of the ice thickness.

      My one time organization used to occasionally tow other folks’ gravimeters behind our aircraft and ships. My recollection is hazy after forty years but I think they were doing mineral exploration, archaeology, and looking for shipwrecks. I was quite impressed by what they were able to find and formed the opinion that they actually knew what they were doing.

      Having said the above, it is also important to note that most published research findings are wrong. Speculation about the structure of an asteroid seems less reliable than finding mineral deposits, ancient walls, and shipwrecks.

      • Published findings wrong because the material is forced by publish or perish pressure in academia. and, I’ve remarked on recent threads that the scientific literature numbered in some thousands up to 2015 and that a determined individual could read all important papers in all sciences, at the time. Today there are over 50million papers in 24,000 journals and growing at 2.5 million a year.

        Like an expansion draft in hockey, the game quality declines with the need to accept mediocre players to pad rosters. In science were talking about a draft that increased players from a few hundred to millions. Steve MacIntyre’s observation after taking down a covey of cliScis over incompetent selection, use and statistical acumen is apropos here:

        “In my opinion, most climate scientists on the Team would have been high school teachers in an earlier generation – if they were lucky. Many/most of them have degrees from minor universities. It’s much easier to picture people like Briffa or Jones as high school teachers than as Oxford dons of a generation ago. Or as minor officials in a municipal government.”…..”… the complete mediocrity of the Team makes their work vulnerable to examination by the merely competent.”

        The consensus is perplexed by their inability to convince people. They first engaged Madison Ave PR promotional communicators and then went to funding” communications faculties” which employed the best

    • No, but the planetary Geoid for ocean levels is affected by densities of the magma/crust below, ice sheet locations/mass, mountain ranges, deep sea trenches and winds and currents amongst other know terrestrial factors. If all the ice in Greenland melted tomorrow, the ocean level immediately around Greenland would not come up the 23 feet of water that Greenland ice holds, but the water would equalize more to the equatorial budge over time and some towards the opposite side of the planet over longer time periods. The gravitational attraction of an ice sheet like Greenland tends to pull up the ocean height around it, as well as around Iceland and Ireland. Along with the mountains undersea of the mid Atlantic ridge which pushes the ocean water up, gravitationally speaking.

      Sea level is not absolute. The sea level is different from one side of the Panama canal to the other with the Pacific side 20 cm higher than the Atlantic due to the geoid. If you factor in salinity, ocean temps and currents and winds, the Pacific Ocean can rise as much as 20 feet, but 45 miles away, the difference between high tide and low in the Atlantic is just 3 feet.

      The ocean level geoid’s variation ranges from −106 m to +85 m, more than 200 m total compared to a perfect mathematical ellipsoid. It is relative to a spirit level, since gravity is a measurement from the earth’s centre as measured by satellites like GRACE. GPS satellites correct for this, otherwise off the coast of Ireland, your GPS would be saying you were 30 m above sea level. This is another reason for sea level rise not being equal everywhere on the planet with an equal amount of melt water entering the ocean.

  2. a concept i cant understand is people thinking we are the ONLY life in the universe? science has already observed the conditions needed for life in many places in our own solar system, this universe is teeming with life.

    • That’s reasonable but we won’t know for sure until we find life in another world.

      Probably life is inevitable wherever the conditions for it exist. But we can’t yet be sure of that.

    • Whilst I consider that it is almost inevitable that life exists somewhere within the great expanse of the universe, do not overlook the fact that it appears very difficult to jump from single cell to multiple cellular organisms, if the experience on this planet is anything to go by.

      obviously, we will have to wait and see what new discoveries turn up.

  3. Why not land on it?

    Fear of contamination hasn’t kept us from landing on other planets, moons, comets and asteroids.

    • DAWN was not designed to have the capability to land. It sounds more PC-trendy and conscientious to boast maintaining the “virginity” of the dwarf.

      • Oh, duh! They mean not crashing it into the surface.
        It says: “On October 19, 2017, NASA announced that the mission would be extended until its hydrazine fuel runs out, possibly in the second half of 2018; afterwards, the spacecraft is expected to remain in a stable orbit around Ceres.”
        Seems data collection continues until something fails and from then on it’s a curious artifact of our presence in space.

      • I know that Dawn wasn’t designed to land, but the next mission to the asteroid belt could do so, and not just crash, but stay there to gather info.

        IMO the asteroid belt offers more opportunity for human colonization than does Mars. In fact, we should probably crash a lot of smaller asteroids and comets into Mars to make it bigger, better and more hospitable, after a few million years of cooling off.

      • @Gabro

        What amazes me is that a scientist of the calibre of Stephen Hawkins considers that we must leave this planet in the near future, and colonise space if we are to survive as a species.

        No matter how dramatic climate change may be on planet Earth, this planet is almost certainly bound to be the most habitable world for the next hundred or so million years. Given our skill at adaption, it would require something extremely dramatic to happen to this world to render it not suitable for us as a species.

        See for example: https://www.popsci.com/stephen-hawking-human-extinction-colonize-mars

        Stephen Hawking is making apocalyptic predictions again. The respected theoretical physicist warns that humanity needs to become a multi-planetary species within the next century if we don’t want to go extinct. Last year, he prophesied that we had maybe 1,000 years left on Earth, and the inspiration for this newly-urgent timeline is unclear—except for the fact that Hawking’s new documentary about colonizing Mars is coming out soon.

        I hope that this view is not a sign of failing cognitive facility.

      • Can anyone name ANYTHING that Hawking has done other than come up with IMAGINARY thought bubbles of UNPROVABLE scientific dribble.?

      • IMO we will become a space-faring species, not because Earth will become uninhabitable soon, but because that’s who we are.

        Earth will become uninhabitable in the distant future, but so far distant that our descendants, if any, will not look much like us.

        Our planet is about half way through its complex, multicellular life stage. We have maybe another 500 million years to go.

  4. Fascinating! Ices, salts, and clathrate hydrates – Oh My!
    Ceres provides a potential source of reaction mass for nuclear powered rockets within the asteroid belt. It is the equivalent of having a ‘gas station’ located within the biggest potential metals mine in the solar system!

    • In addition, the xenon-ion drive and small deep-space transponder demonstrated their fitness as interplanetary robot craft features.

  5. I think there would be much more interest, especially among young people these days, in exploring Uranus.

  6. Planet Earth calling NASA… Asteroid Ceres as we know it today could never have had oceans of liquid water, period, end of story. According to NASA’s own data https://solarsystem.nasa.gov/planets/ceres/facts Ceres surface gravity is 0.28 m/sec^2, i.e. 1/35th of earth’s surface gravity. Its escape velocity is 1,855 km/h. Earth’s escape velocity is 21.7 times greater, at 40,284 km/h.

    Given those very low numbers, a liquid ocean was never possible. You’re left with 2 options…
    1) Ceres accreted water ice from grazing collisions with comets. etc
    2) Ceres is one remnant of an “exploded planet”, which had oceans in its day

    • YES SIR!!!
      Nor did it ever have an atmosphere at a high enough pressure to support the bonding of 2 “H’s” to an “O”.

Comments are closed.