Tag Archives: Jonathan Amos

Mars, shmars.  How about Venus?

The surface of Venus is hostile as all get out.  Puny humans are having trouble even landing probes, and there is zero probability we would ever try to live there.

But NASA didn’t get where it is today by not thinking big.  Even before the blockbuster discovery of phosphine in the clouds [3], some of the big brains at NASA Langley have been exploring concepts for visiting and exploring the atmosphere of Venus, High Altitude Venus Operational Concept (HAVOC)

Let’s start with the big, juicy part:  airships!  Giant, extraterrestrial airships!

I’m sold!

The airships could be crewed!

The mission concept involves dropping Lighter Than Whatever-is-in-the-Air craft from orbit, to cruise high in the atmosphere where the pressure and temperature isn’t as extreme.  Probes could dive deeper and then bob back up with data.

At this altitude in the Venusian atmosphere there is substantial solar radiation for power, yet radiation levels are pretty low.  Practically a day at the beach, compared to Mars!

OK, this mission isn’t trivial to do.

Key technical challenges for the mission include performing the aerocapture maneuvers at Venus and Earth, inserting and inflating the airship at Venus, and protecting the solar panels and structure from the sulfuric acid in the atmosphere.” (From [4])

Yeah, operating an airship in a bath of sulfuric acid is kind of a challenge.

And getting there involves a screaming descent from orbit, slowing to a reasonable speed, deploying and inflating the envelope—amid 100 km/hr winds.  What could possibly go wrong?

A human crew could be accommodated in a submarine-like aerial rover or, as Evan Akerman puts it, “sky cities”.

From [4]
Now you are just teasing me!

Who hasn’t been waiting forever for Sky Cities on Venus?

Hey Silicon Valley space nuts!  This is way, way cooler than a suicide mission to “settle” Mars.

  1. Evan Ackerman, NASA Study Proposes Airships, Cloud Cities for Venus Exploration, in IEEE Spectrum – Aerospace, September 13, 2020. https://spectrum.ieee.org/aerospace/space-flight/nasa-study-proposes-airships-cloud-cities-for-venus-exploration
  2. Jonathan Amos, Is there life floating in the clouds of Venus?, in BBC News – Science & Environment, September 14, 2020. https://www.bbc.com/news/science-environment-54133538
  3. Jane S. Greaves, Anita M. S. Richards, William Bains, Paul B. Rimmer, Hideo Sagawa, David L. Clements, Sara Seager, Janusz J. Petkowski, Clara Sousa-Silva, Sukrit Ranjan, Emily Drabek-Maunder, Helen J. Fraser, Annabel Cartwright, Ingo Mueller-Wodarg, Zhuchang Zhan, Per Friberg, Iain Coulson, E’lisa Lee, and Jim Hoge, Phosphine gas in the cloud decks of Venus. Nature Astronomy, 2020/09/14 2020. https://doi.org/10.1038/s41550-020-1174-4
  4. NASA Systems Analysis and Concepts Directorat. High Altitude Venus Operational Concept (HAVOC). 2020, https://sacd.larc.nasa.gov/smab/havoc/.


And Nioghalvfjerdsfjorden is melting fast, too

I guess this is another installment of “The Ice is Melting Everywhere”.  It’s getting pretty repetitive.

At least some of the glaciers off Antarctic are melting, probably melting rapidly.

At the same time, the entire island of Greenland is meltingRapidly.

Obviously, this melting includes the glaciers, including way up north.

This week researchers discuss imagery and data from the GRACE satellite which show that the glacier denoted N19, called Nioghalvfjerdsfjorden, is breaking up [1].  Thinned by warming air and sea water, the river of ice is shredding.

From [1]

And, by the way, the glaciers are melting in Alaska, too.  This summer Kathryn Hansen reported on imagery of the retreating glaciers in southwestern Alaska [2-4]. <<cites, links>>  It’s not a complicated story:  ‘Glacier bay’ is almost glacier free and the remaining glaciers are rapidly changing.

Basically, the ice is melting everywhere.

  1. Jonathan Amos, Climate change: Warmth shatters section of Greenland ice shelf, in BBC News – Science & Environment, September 14, 2020. https://www.bbc.com/news/science-environment-54127279
  2. Kathryn Hansen, Grand Plateau Glacier, in NASA Earth Observatory, August 13, 2020. https://earthobservatory.nasa.gov/images/147110/grand-plateau-glacier
  3. Kathryn Hansen, Inlet’s Iceberg Maker Is Nearly Gone, in NASA Earth Observatory, August 31, 2020. https://earthobservatory.nasa.gov/images/147171/inlets-iceberg-maker-is-nearly-gone
  4. Kathryn Hansen, Where Ice Still Flows into Glacier Bay, in NASA Earth Observatory, September 16, 2020. https://earthobservatory.nasa.gov/images/147171/inlets-iceberg-maker-is-nearly-gone

Thwaites Glacier Is Melting Fast

Thwaites Glacier Is Melting Fast

West Antarctica appears to be melting faster than other parts of the continent, and no place is changing more rapidly than the glaciers flowing into the (warming) ocean.

Understanding what is happening to these glaciers will tell us a lot about what is happening in Antarctica.  For this reason, we are “sciencing the hell” out of it.  The International Thwaites Glacier Collaboration (ITGC) has been studying the ice, snow, air, and sea floor for the last year.

This summer the ITGC reports important new results about the sea bed under the Thwaites Glacier [2, 3].  The new results are from sonar and gravity measures which together give some details of the sea bed under the Thwaites glacier.

These findings, even though incomplete, are significant.  They show that, as suspected, there are deep canyons under the glacier, through which warm sea water can flow under the ice.  In particular, the measures show that channels extend completely around a ridge of rock that is pinning the glacier.  This means that warm water can get under the ice.

From [1]
Warm water will, of course, melt the ice from below.  It also lubricates the ice/rock surface, which speeds the flow of the ice from inland out to the sea.  Together, these effects will promote the loss of ice, as more ice descends to the sea and breaks off.

The new studies are incomplete—there are still areas that have not been well mapped.  But the new information can refine models of the glacier, and improve predictions of how the ice is changing.

  1. Jonathan Amos, Thwaites: ‘Doomsday Glacier’ vulnerability seen in new maps, in BBC News – Science & Environment, September 9, 2020. https://www.bbc.com/news/science-environment-54079587
  2. K. A. Hogan, R. D. Larter, A. G. C. Graham, R. Arthern, J. D. Kirkham, R. Totten Minzoni, T. A. Jordan, R. Clark, V. Fitzgerald, A. K. Wåhlin, J. B. Anderson, C. D. Hillenbrand, F. O. Nitsche, L. Simkins, J. A. Smith, K. Gohl, J. E. Arndt, J. Hong, and J. Wellner, Revealing the former bed of Thwaites Glacier using sea-floor bathymetry: implications for warm-water routing and bed controls on ice flow and buttressing. The Cryosphere, 14 (9):2883-2908, 2020. https://tc.copernicus.org/articles/14/2883/2020/
  3. T. A. Jordan, D. Porter, K. Tinto, R. Millan, A. Muto, K. Hogan, R. D. Larter, A. G. C. Graham, and J. D. Paden, New gravity-derived bathymetry for the Thwaites, Crosson, and Dotson ice shelves revealing two ice shelf populations. The Cryosphere, 14 (9):2869-2882, 2020. https://tc.copernicus.org/articles/14/2869/2020/

New Map of Antarctic Ice Sheets

The ice is melting everywhere.  But some places are melting faster than others.

Down Antarctica way, there is a lot of ice on the land (miles deep in places) and on the surrounding seas.  The sea ice is particularly likely to melt, because it is exposed to the ocean and air, which are warming.  But this is a complex process, with new ice forming constantly, and glacier ice flowing off the land onto the see.  The amount of ice is changing, but the changes are proceeding at different paces in different places.

This summer, researchers from the US published a new map of Antarctica that combines data from multiple satellites to estimate the rate the ice is melting for all the coast of the continent.  The new dataset estimates the state of the ice in a 10km area, and 500m for recent years. This is remarkably detailed—there are tens of thousands of kilometers of ice sheet!

Fig. 1: Basal melt rates of Antarctic ice shelves estimated using CryoSat-2 altimetry. (from [1])
The detailed data is extremely useful for refining computational models to reflect recent history.  The data shows year to year fluctuations in different parts of Antarctica.  These can be used to improve models of the ocean and atmosphere and interactions with the sea ices.

The detailed data also points to critical areas that are changing rapidly.  These will be high priority targets for careful examination.

The melting sea ice doesn’t affect sea level, but does contribute cold, fresh water to the ocean.  Knowing where and how much meltwater arrived will help understand the effects on ocean currents that affect wider areas.  And, of course, when the sea ice melts, it can release glaciers to flow faster into the sea –which ultimately will increase sea level.

Nice work.

  1. Susheel Adusumilli, Helen Amanda Fricker, Brooke Medley, Laurie Padman, and Matthew R. Siegfried, Interannual variations in meltwater input to the Southern Ocean from Antarctic ice shelves. Nature Geoscience, 2020/08/10 2020. https://doi.org/10.1038/s41561-020-0616-z
  2. Jonathan Amos, Climate change: Satellites record history of Antarctic melting, in BBC News – Science & Environment, August 10, 2020. https://www.bbc.com/news/science-environment-53725288

Ice satellites doubling up

What’s better than one scientific instrument?

Obviously–it’s more than one different scientific instruments that measure the same thing in different ways.  Belt and suspenders, and all that.  Trust, but verify your measurements.

This summer the European Space Agency has decided to change the orbit of its Cryosat-2 satellite, climbing a few hundred meters [1].

After the maneuver, Cryosat-2’s orbit will have a resonance with NASA’s Icesat-2, so that every day and a half the two spacecraft will measure the same area of the Southern ice simultaneously.

Dr Tommaso Parrinello, told BBC News: “Icesat is quite a bit below us so we can’t go down to meet them, but by going up we find this incredible resonant orbit in which for every 19 orbits for us and 20 orbits for them – we will meet at the poles within a certain time lag. Basically, every 1.5 days, we meet over the poles within a few hours of each other and that means we can observe the same ice almost simultaneously.” (From [2])

The point of the exercise is to get a combined measurement from the two sattelites.  Icesat uses lase altimetry (AKA, “space lasers” : – )) to measure the height of the ice on the sea.  Cryosat-2 uses radar altimetry (AKA, “space radar” : – )) which measures the depth of the snow.  Combining the two, it will measure the depth of the snow on top of the ice, giving a more complete picture of sea and air conditions.

I gather that there really isn’t any data on this ice+snow, so computational models have been using generic theoretical estimates, rather than actual ground truth.  So, the new observations will be extremely valuable for improving the accuracy of the climate models.


  1. Jonathan Amos, Esa and Nasa line up satellites to measure Antarctic sea-ice, in BBC News – Science & Environment, July 7, 2020. https://www.bbc.com/news/science-environment-53326490


Dinosaur Trackway With A Splashy Interpretation

In my lifetime there has been an astonishing explosion of fossil trackways, footprints and other traces of dinosaurs and ancient animals (e.g., this, this, this, this, this), as well as ancient humans and even fish).

The cool thing about trackways is that they capture the behavior of the living animals in a way that no bone or other bodily trace can ever do.  How fast did an animal walk?  The tracks tell us exactly how they walked.  What animals lived together?  The trackways show us.  And so on.

The big problem—and it’s a huge problem—is that the tracks usually aren’t associated with the remains of a specific animal.  So we know that “something walked this way”, but we generally can’t tell what it was.

Not that paleontologists don’t make their best guesses.

This can lead to some serious controversy.

Case in point: this spring researchers from Korea report on an interesting trackway of an animal running on its hind legs like an ostrich [2].  The fossils date to the Cretaceous period, 120 millions years ago, and are identified as “crocodylomorphs”, known from other fossils.

The interesting thing is that this is fully bipedal locomotion (no front paws touching), which was not generally associated with these animals before.  If this interpretation is correct, then this shows that these ancestors of the crocodiles (not technically dinosaurs) were quite different than their descendants.

This interpretation depends on identifying what animals make the prints.  The researchers marshal evidence:  besides the shape of the track, there are traces of skin, and also evidence of how the weight is distributed (heel first).  They argue that these characteristics distinguish them from tracks of dinosaurs and pterosaurs, and match the proposed crocodylomorphs.

On the other hand, these would be very large compared to similar animals found, and there isn’t any direct evidence of what animals actually made the tracks. So we have to be cautious.

This is an interesting and pretty careful study, though I’d say their conclusions need to be taken with a grain of 100 million year old salt.

  1. Jonathan Amos, Fossil tracks left by an ancient crocodile that ‘ran like an ostrich’, in BBC News – Science & Environment, June 11, 2020. https://www.bbc.com/news/science-environment-53011567
  2. Kyung Soo Kim, Martin G. Lockley, Jong Deock Lim, Seul Mi Bae, and Anthony Romilio, Trackway evidence for large bipedal crocodylomorphs from the Cretaceous of Korea. Scientific Reports, 10 (1):8680, 2020/06/11 2020. https://doi.org/10.1038/s41598-020-66008-7


PS.  Wouldn’t “Cretaceous crocodylomorphs” be a great name for a band?

Space Lasers Measuring the Cryosphere

The ice is melting everywhere.

This is important, and, fortunately we are science-ing the hell out of it.

The science includes computational modelling, remote sensing, and in situ measurements.

One important thrust has been increased satellite observation of the polar regions, to build a detailed, continuing record of the snow and ice cover.

Or, as the BBC headline put it, “NASA space lasers track melting of Earth’s ice sheets” [1].

Anything involving “space lasers” has got to be cool, right?

: – )

The space lasers in question are the ICESats, which have laser altimeters that have been measuring the height and thickness of the snow and ice around the world.

This spring researchers report on a careful analysis of ICESat data from 2003 – 2019 [2]. The study combined earlier data from ICESat with the improved and higher resolution data from ICESat-2.  The combined data is incomplete, but is a comprehensive record of the ice mass of ice shelves, glaciers, and interiors.

ICESat-2 has much higher resolution, which means the data can account for more of the real geography of the ice, such as large crevasses.  This is particularly important where the ice is in the process of melting, because it will lose mass by hollowing out before the total coverage changes.

IceSat-2’s resolution allows it to map crevasses in the ice sheet surface. (Image credit: NASA/SCRIPPS/S.ADUSUMILL) (From [1])
The total amount of ice is a critical factor, because if and when the ice decreases (melts), the water flows into the oceans, raising sea level.  And vice versa.  So, big changes in these icy areas mean, among other things, changes in sea level everywhere.

Current understanding tells us that there are a number of processes that contribute to the accumulation, retention, and loss of ice.  The temperature of the air, as well as humidity, prevailing winds, and the number of storms contribute to the amount of snowfall (new ice) and the melting of surface snow and ice.  Ocean temperature and currents contribute to the rate of melting of sea ice.  And there are plenty of complicated interactions between oceans and air, as well as the dynamic behavior of the ice, as glaciers flow faster or slower into the sea.  And, of course, as the ice melts, the exposed surfaces are darker, absorbing more solar energy, and heating the ocean and atmosphere even faster.

The upshot is that things are so complicated that we need as good of data as we can get to make sure the models are following reality, as well as to understand the state of play.

The new study  is broadly consistent with existing work, showing areas of loss and areas of gain. (e.g., this, this)  While there is increased snow accumulation in places, there is thinning and reduction in ice shelves, and increase flow in glaciers.

Overall, they see over 300 Gigatons of ice loss over this period, which they calculate contributed to a 14mm rise in global sea level.  (This is probably an underestimate, because the data does not cover everywhere for the whole period.)

The bottom line is that the ice was melting for the last 15 years, and looks to continue to melt, quite probably at a faster rate.  ICESat-2 will surely document the changes over the next few years.

  1. Jonathan Amos, NASA space lasers track melting of Earth’s ice sheets, in BBC News – Science & Environment, April 30, 2020. https://www.bbc.com/news/science-environment-52479316
  2. Ben Smith, Helen A. Fricker, Alex S. Gardner, Brooke Medley, Johan Nilsson, Fernando S. Paolo, Nicholas Holschuh, Susheel Adusumilli, Kelly Brunt, Bea Csatho, Kaitlin Harbeck, Thorsten Markus, Thomas Neumann, Matthew R. Siegfried, and H. Jay Zwally, Pervasive ice sheet mass loss reflects competing ocean and atmosphere processes. Science:eaaz5845, 2020. http://science.sciencemag.org/content/early/2020/04/29/science.aaz5845.abstract


Chicxulub Impact study

Chicxulub day was a bad day for our planet.

Recent studies have confirmed the global disaster, wiping out dinosaurs and lots of other species, messing up the climate for centuries, and, who knows, spreading debris over to Mars and Venus (e.g., this, this, this, this, this, this, this).

But how could one impact be so destructive?  How could it affect the whole planet?

This spring an international team of researchers report a study of the Chicxulub crater that suggests that the body hit at a steep 45-60 degree angle from the northeast [2].  Recent measurements has accumulated evidence that the crater is elongated northeast to southwest.  The new study created 3D simulations to examine how this pattern could occur.

“In summary, our numerical simulations of oblique Chicxulub-scale impacts appear to be most consistent with the internal structure of the Chicxulub crater for a steeply inclined impact angle of 45–60° to the horizontal.” ([2], p.7)

Their basic conclusion is that the simulations are consistent with a steep impact angle.


Now, I’m no craterologist, but I’m pretty sure that it is not easy to tell the angle of impact from an old crater.  So there has to be a bit of skepticism about this finding.

On the other hand, the results are plausible.

For one thing, a 60 degree angle gives estimated kinetic energy that is consistent with other evidence.  And, of course, steep impact angles distribute the debris farther, which is consistent with the planet-wide destruction and the famous Iridium layer that marks the K–Pg boundary around the world.  A 60 decree impact also produces the maximum evaporation of the sedimentary rocks, i.e., maximum green house gas emission.

“a trajectory angle of 30–60° constitutes the worst-case scenario for the high-speed ejection of CO2 and sulfur by the Chicxulub impact” ([2], p. 7)

As Jonathan Amos puts it, this was ‘a perfect storm’:  the worst case angle of impact (and it was in one of the worst possible locations, shallow water).

It was a very unlucky day for the Earth.

  1. Jonathan Amos, Dinosaur asteroid’s trajectory was ‘perfect storm’, in BBC News – Science & Environment, May 26, 2020. https://www.bbc.com/news/science-environment-52795929
  2. G. S. Collins, N. Patel, T. M. Davison, A. S. P. Rae, J. V. Morgan, S. P. S. Gulick, G. L. Christeson, E. Chenot, P. Claeys, C. S. Cockell, M. J. L. Coolen, L. Ferrière, C. Gebhardt, K. Goto, H. Jones, D. A. Kring, J. Lofi, C. M. Lowery, R. Ocampo-Torres, L. Perez-Cruz, A. E. Pickersgill, M. H. Poelchau, C. Rasmussen, M. Rebolledo-Vieyra, U. Riller, H. Sato, J. Smit, S. M. Tikoo, N. Tomioka, J. Urrutia-Fucugauchi, M. T. Whalen, A. Wittmann, L. Xiao, K. E. Yamaguchi, N. Artemieva, T. J. Bralower, Iodp-Icdp Expedition 364 Science Party, and Third-Party Scientists, A steeply-inclined trajectory for the Chicxulub impact. Nature Communications, 11 (1):1480, 2020/05/26 2020. https://doi.org/10.1038/s41467-020-15269-x


A Black Hole In Our Neighborhood

Over the last year I’ve been watching science shows on TV, and I’m now far more interested in black holes than ever before.  Black holes are everywhere, and they are driving a lot of the life of the galaxy (at least in the “light” universe—who knows what the dark matter and energy are really up to.)

This spring European researchers report on a cool possible black hole, tagged HR 6819 [2].

“HR 6819 is a hierarchical triple star with a nonaccreting BH in the inner binary.” ([2], p. 4)

This observation is interesting in a number of ways.  For one thing, it’s a “dark black hole” or “quiet black hole”, not emitting extravagant energy from accretion.  It is observed from the peculiar orbits of two nearby stars, locked in a fast tango with the presumed black hole.  The closest in is circling about every 40 days, which is a pretty good clip for a star!  (These stars make it relatively easy to calculate the mass of the putative black hole.)

A second interesting thing is that it is very close, “only” 1,000 light years away.  This is practically next door, especially compared to other known black holes.  There should be black holes all over the place, but they are hard to find except when they are blasting energy as they eat stars.  This observation sort of confirms the notion that there are a lot of black holes out there, even if we can’t see them.

“The existence of an entire population of quiet BHs is also suggested by the relative proximity of HR 6819.” ( [2],, p. 4)

Third, the black hole is “only” about four times the mass of our sun, which is one of the smallest ever observed. There should be black holes of many masses, but, obviously, the big ones are easier to find.

And finally, the stars are visible to the naked eye, at least down south when the sun isn’t in the way [1].  So, that’s super cool.

  1. Jonathan Amos, ‘Nearest black hole to Earth discovered’, in BBC News – Science & Enviroment, Nay 6, 2020. https://www.bbc.com/news/science-environment-52560812
  2.  Th Rivinius, D. Baade, P. Hadrava, M. Heida, and R. Klement, A naked-eye triple system with a nonaccreting black hole in the inner binary. Astronomy & Astrophysics, 637  May 2020. https://doi.org/10.1051/0004-6361/202038020

The Magnetic Pole Wandering – A Lot!

Everybody knows that the Earth’s poles move as the planet wobbles, and that the magnetic North pole isn’t actually at the pole, and, in fact wanders.  But when I was a lad, all this wandering seemed to be slow, at geologic time scales.  And I hadn’t actually heard anything much about it in the ensuing decades.

So, I was rather surprised to read that the magnetic pole has moved a lot even in my lifetime, and is, in fact, cruising along at some 50 km per year for the last 20 years [1].  Woah!

This spring, researchers from Leeds U. report a study which shows what is happening in the mantle [2].  The magnet pole is produced by irregularity in the Earth’s mantle, which has a big blob of iron rich magma that our compasses pick up.  The recent sprint reflects movement in the core, as the blob shifts towards Siberia.

Basically, they find two “large-scale lobes of negative magnetic flux” (p. 387).  The one under Canada is weakening slightly, with the result that the balance is shifting to the one under Siberia.

Reading about this, I was reminded that there are actually three poles, the geographic pole (the axis of rotation), the geomagnetic pole (the pole of the magnetic field), and the magnetic pole (where flux lines are vertical).  The first two  aren’t moving, the third is the one that is cruising.

Image credit: P.Livermore (From [1])
This movement isn’t particularly noticed unless you are trying to use a compass.  Oh, wait, smart phones have a magnetic compass in them, so everybody is impacted!   This migration has been incorporated in updates to models used to correct magnetic compass readings, which I didn’t even know existed, but obviously must.

(And isn’t it nice to read about something that isn’t Anthropogenic.  In fact, humans are completely irrelevant to this phenomenon.)

  1. Jonathan Amos, Scientists explain magnetic pole’s wanderings, in BBC News – Science & Environment, May 6, 2020. https://www.bbc.com/news/science-environment-52550973
  2. Philip W. Livermore, Christopher C. Finlay, and Matthew Bayliff, Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation. Nature Geoscience, 2020/05/05 2020. https://doi.org/10.1038/s41561-020-0570-9


PS.  The title of the Nature article alone has not one but three great names for a Band name:

Flux Lobe Elongation
Magnetic Pole Acceleration
Towards Siberia