S27E56: Saturn's Geyser Moon Mysteries: Tidal Forces and Life's Potential

[00:00:00] This is SpaceTime Series 27 Episode 56 for broadcast on the 8th of May 2024.

[00:00:06] Coming up on SpaceTime, new evidence of how geysers erupt on the Saturnian ice moon Enceladus,

[00:00:13] NASA scientists gearing up for solar storms on Mars, and confirmation it was space junk which

[00:00:20] slammed into a Florida home last month. All that and more coming up on SpaceTime.

[00:00:25] Welcome to SpaceTime with Stuart Gary

[00:00:46] A new study suggests that the spectacular geysers erupting from the Saturnian ice moon Enceladus'

[00:00:52] south pole tiger stripes are caused by the same process which triggers California's San Andres

[00:00:57] fault. Over the course of its elliptical orbit, Enceladus is squeezed unevenly by Saturn's

[00:01:03] gravitational pull, causing the tiny moon to deform from a spherical shape to an almost

[00:01:08] football-like shape and then back again. This continuous cyclic stress causes a phenomenon

[00:01:14] within Enceladus known as tidal heating, and it generates enough energy to maintain what's

[00:01:19] believed to be a global subsurface ocean deep beneath the icy Enceladian crust.

[00:01:25] At Enceladus' south pole, where it's thought the ice is the thinnest, a large number of

[00:01:30] jets spray icy water particles out into space from a set of jagged 150-kilometre-long

[00:01:35] fault lines known as tiger stripes, and this ejected material then coalesces above the moon's

[00:01:42] surface in the form of plume or geyser. Samples of this plume material, analysed by NASA's

[00:01:47] Cassini mission, suggest that the chemical conditions believed to be necessary for life

[00:01:52] may well exist in the ocean deep beneath Enceladus' surface. Now new research led by

[00:01:58] Alexander Byrne and Mark Simons from Caltech has developed a detailed geophysical model

[00:02:03] which characterises the motion of these tiger stripe fault lines and provides new insights

[00:02:07] into the geological processes controlling the geyser activity. The plume above Enceladus'

[00:02:13] south pole varies in intensity, waxing and waning in strength over time to produce two

[00:02:18] notable bright peaks in the mission during the moon's 33-hour orbit around Saturn.

[00:02:23] Now it's long been theorised that tidal forces cause the tiger stripe fault lines to open

[00:02:28] and close, sort of like elevator doors, allowing them to emit more or less material in cycles that

[00:02:34] correspond to those tides. However there's a problem here, they don't accurately predict

[00:02:39] the timing of the peaks in the plume brightness. More problematic, the fault opening mechanism

[00:02:44] actually requires more energy than what's expected to be available from tidal flexing alone.

[00:02:50] The new research reported in the journal Nature Geoscience suggests that observed variations

[00:02:55] in Enceladus' plume strength may be due to the tiger stripe faults moving in a strike-slip fashion

[00:03:01] with one side shearing past the other, similar to the style of fault motion that produce

[00:03:05] earthquakes along faults like California's San Andreas. The energy required for such

[00:03:10] fault motion is considerably less than that required by the opening-closing mechanism.

[00:03:16] To support the hypothesis, Byrne and Simons developed a sophisticated numerical model to

[00:03:20] simulate strike-slip motion along Enceladus' faults. These models also consider the role of

[00:03:26] friction between the faults' icy walls, which causes deformation to be sensitive to both

[00:03:31] compressional stresses that tend to clamp and unclamp the fault and shear stresses that

[00:03:35] tend to drive slip on the fault. The good news is the numerical model was able to simulate

[00:03:41] slip along the tiger stripes in a manner which matches the variations in plume brightness

[00:03:46] as well as spatial variations in the surface temperature, suggesting that the jets are

[00:03:50] indeed controlled by a strike-slip motion over Enceladus' orbit. The research has theorized

[00:03:56] that the individual jets occur at puller parts in the faults, bent sections in the fault that

[00:04:01] open under regional strike-slip motion. Now recent separate research by scientists at NASA's

[00:04:07] Jet Propulsion Laboratory also examined the tiger stripe region and found geological evidence

[00:04:12] for puller parts along the faults and it was located right at the location of the jets.

[00:04:17] Back in 2005, the Cassini mission flew by Enceladus sampling jet material and discovered

[00:04:24] that the plumes contain elements like carbon and nitrogen. That indicates that the subsurface

[00:04:29] ocean could currently harbor conditions suitable for life. In addition to the presence of these

[00:04:35] and other chemical components, key geophysical conditions such as sufficient heat production

[00:04:40] and nutrient flux between the core of the ocean and the surface are required for habitability.

[00:04:46] Simon says for life to evolve conditions for habitability have to be just right for a long

[00:04:51] time, not just an instant. On Enceladus you would need a long-lived ocean. Geophysical and

[00:04:57] geological observations can provide key constraints in the dynamics of the core and the crust

[00:05:02] as well as the extent to which these processes have been active over time.

[00:05:07] Byrne says some detailed measurements of motion along the tiger stripes are now needed to confirm

[00:05:11] the hypothesis. For instance, scientists can now image fault slips such as earthquakes on Earth

[00:05:17] using radar measurements from orbiting satellites and applying these same methods at Enceladus

[00:05:22] would allow scientists to better understand the transport of material from the ocean to

[00:05:26] the surface, the thickness of the ice crust itself and the long-term conditions which may

[00:05:31] enable life to form and maybe even evolve on Enceladus. Now the thing you've got to remember

[00:05:37] about life is that if we find life on Mars, well that's a big deal but the Earth and Mars

[00:05:43] have been swapping rocks for billions of years and consequently any evidence of life

[00:05:48] we find on Mars could have originated on Earth or on the other hand we might all be Martians

[00:05:52] with life starting on Mars and then being thrown to Earth by some asteroid impact.

[00:05:58] But in the outer solar system on icy moons like Europa or Saturn's Enceladus where there's a huge

[00:06:04] thick icy barrier between space and what's happening below the crust, well if life develops

[00:06:10] there then it could be anywhere and that's an amazing possibility. This is space time.

[00:06:18] Still to come NASA astronauts gearing up for solar storms on Mars and confirmation that space

[00:06:24] junk slammed into a home in Florida. All that and more still to come on space time.

[00:06:45] As our sun's activity continues to ramp up as it approaches solar max, the climax of its

[00:06:51] 11-year solar cycle, scientists with NASA are preparing to observe how the increase

[00:06:55] in solar storms and radiation will affect equipment and possibly in the future humans

[00:07:00] on the red planet Mars. Now during solar maximum the sun's especially prone to throwing

[00:07:06] off fiery tantrums these include solar flares and coronal mass ejections which can launch plasma

[00:07:12] and radiation deep into space. When these solar events erupt they're known as solar or geomagnetic

[00:07:18] storms. Now Earth's magnetic field help shield this planet from the many effects of these storms

[00:07:25] some however do get through damaging or destroying satellites affecting navigation

[00:07:30] and communication systems and even causing blackouts on the planet's surface. They also

[00:07:35] pose a threat to astronauts orbiting the planet and even people in high-flying aircraft

[00:07:40] and of course they also cause the spectacular northern and southern lights the aurora borealis

[00:07:45] and aurora australis which have been on display over the last few weeks. But Mars is

[00:07:51] a very different case. See the red planet lost its global magnetic field long ago that leaves

[00:07:57] it more vulnerable to the sun's energetic particles. Now in the months and years ahead

[00:08:02] depending on exactly how long it takes to reach solar maxima two of NASA's Mars spacecraft will

[00:08:07] have an unprecedented opportunity to study just how this intense solar activity affects the red

[00:08:13] planet. And that's important to know because before sending people to Mars space agencies

[00:08:18] need to determine among other things just what kind of radiation protection they'll need.

[00:08:23] Shannon Curry from the University of Colorado Boulder is the principal scientist for NASA's

[00:08:28] Mars atmosphere and volatile evolution spacecraft MAVEN. She says we don't have a solid handle on

[00:08:34] what effects radiation is likely to have on humans and assets on the Martian surface.

[00:08:40] So when a large space weather event hits Mars she wants to be able to study and understand

[00:08:45] the solar radiation better before astronauts go there. MAVEN's operated by NASA's Goddard

[00:08:51] Space Flight Center in Greenbelt Maryland. It observes radiation and solar particles from

[00:08:56] high orbit above the Martian surface. The planet's thin atmosphere can affect the

[00:09:01] intensity of particles by the time they reach the surface which is where NASA's Mars Curiosity

[00:09:07] rover in Gale Crater comes in. Data from Curiosity's radiation assessment detector will

[00:09:12] help scientists understand how radiation breaks down carbon-based molecules on the Martian

[00:09:17] surface a process that could be affecting whether or not signs of ancient microbial

[00:09:22] life are even present on Mars. The car-sized six-wheeled rover has also been providing NASA

[00:09:27] with an idea of just how much shielding from radiation astronauts could expect by using caves

[00:09:33] or lava tubes or even cliff faces for protection. When a solar event occurs scientists look both at

[00:09:39] the quantity of the solar particles and also how energetic they are. So you can have a

[00:09:44] million particles with very low energy or just 10 extremely high energy particles. While MAVEN's

[00:09:50] instruments are more sensitive to low energy ones, Curiosity's got the only instrument capable

[00:09:54] of seeing high energy ones which make it through the atmosphere down to the surface.

[00:09:59] When MAVEN detects a big solar flare the orbiter's team lets the Curiosity team know

[00:10:04] about it so they can watch for changes in the data. The two missions can even assemble a time

[00:10:09] series measuring changes down to the half second as particles arrive in the Martian

[00:10:14] atmosphere interact with it and then eventually strike the surface down below.

[00:10:18] The MAVEN mission also leads an early warning system that lets other Martian spacecraft know

[00:10:23] that the radiation levels are about to rise. This heads up enables mission scientists to turn

[00:10:29] off instruments that could be vulnerable to solar flares and radiation which can interfere

[00:10:33] with system electronics and communications. Beyond helping to keep astronauts and spacecraft

[00:10:39] safe studying solar maxima on Mars but also provide new insights into why Mars changed from

[00:10:45] being a warm wet world with an earth-like environment capable of harbouring life billions

[00:10:50] of years ago to the freeze-dried desert it's become today. Right now Mars is at a point

[00:10:56] in its orbit where it's closest to the Sun which heats up the atmosphere. That can cause

[00:11:01] billowing dust storms to blanket the surface. Sometimes these storms merge and become global.

[00:11:07] While there's little water left on Mars most of it is in the form of ice under the surface

[00:11:12] and especially at the poles. But some still circulates as vapor in the atmosphere.

[00:11:18] Scientists have long wondered whether global dust storms help eject this water vapor

[00:11:23] lofting it high above the planet where the atmosphere is getting stripped away by the constant

[00:11:27] erosion of solar winds and storms. One theory is that this process repeated enough times over

[00:11:34] eons might explain how Mars went from having lakes and rivers to having virtually no surface

[00:11:40] water today. And if a global dust storm were to occur at the same time as a solar storm it would

[00:11:45] provide a great opportunity to test that theory. Curry says scientists are especially excited

[00:11:51] because this particular solar maxima is happening at the start of the dustiest season on Mars.

[00:11:56] But they also know that a global dust storm is a fairly rare occurrence.

[00:12:01] This is a big year for NASA's maven orbiter. What it could learn can someday help future

[00:12:07] astronauts safely land on Mars and provide us with a new view of the sun.

[00:12:13] 10 years ago we sent maven to Mars to measure space weather and how it interacts with the

[00:12:18] upper atmosphere. This includes solar flares which are giant explosions on the sun which

[00:12:25] send radiation into space. Every 11 years the sun goes through cycles of activity.

[00:12:31] This year we've seen more space weather than we ever have during the entire mission.

[00:12:37] And while solar flares can occur at any time they occur more frequently and more intensely

[00:12:42] at the peak of the cycle called solar maxima. Right now we're almost at that peak and I'm

[00:12:48] really excited about what solar flares can teach us about the red planet.

[00:12:53] Maven is one of two missions studying radiation at Mars. The orbiter is able to observe

[00:12:59] many phenomena from the sun including radiation, high energy particles, and magnetic fields.

[00:13:05] Maven can also see stunning auroras from its vantage point high above the planet

[00:13:11] which future astronauts might be able to see someday.

[00:13:15] Meanwhile down on the surface of Mars the Curiosity rover has a radiation detector

[00:13:20] called RAD. It studies high energy particles that get all the way through the atmosphere and

[00:13:25] down to the surface. Together maven and curiosity give us a better understanding

[00:13:30] of the radiation environment at Mars. Studying how intense solar flares can get during solar

[00:13:36] maximum can help NASA develop protection for future astronauts, robots, and spacecraft.

[00:13:43] There's another advantage to studying the sun from Mars. Here on Earth we can only see one

[00:13:49] side of the sun but when Maven is on the other side it can spot activity coming days

[00:13:54] before we can. On a personal note Maven is my spacecraft baby and I am so excited about

[00:14:02] observing the next few years of solar flares, space weather, and the atmosphere of Mars.

[00:14:08] That's Shannon Curry from the University of Colorado Boulder and principal scientist for

[00:14:13] NASA's Mars Atmospheric and Volatile Evolution spacecraft Maven and this is Space Time.

[00:14:19] Still to come scientists confirm that space junk slammed into a Florida home last month

[00:14:24] and later in the science report a new study confirms that teens who spend too much time

[00:14:30] online are more likely to skip school. All that and more still to come on Space Time.

[00:14:51] NASA has confirmed that an object which crashed into a Florida home last month was

[00:14:56] a chunk of space junk jettisoned from the International Space Station. The debris was composed

[00:15:01] of the metallic alloy in canal. It was around 10 centimeters long and a mass of about 0.7

[00:15:07] kilograms. The object was originally part of the EP9 cargo pallet containing a staunchen

[00:15:13] support used to mount old batteries which had been released from the orbiting outpost during

[00:15:18] a spacewalk back in 2021. Now mission managers had been tracking it ever since watching its

[00:15:24] orbit slowly decay. Now it should have burnt up during atmospheric re-entry but instead it

[00:15:30] survived eventually smashing through the roof and two floors of a Naples home. The trajectory

[00:15:35] of the space junk closely matched the official predictions for the atmospheric burn up of the

[00:15:39] cargo pallet fragment. NASA says it's still investigating how the debris survived atmospheric

[00:15:45] re-entry and they'll update its engineering models accordingly. This is Space Time and time

[00:16:07] now to take another brief look at some of the other stories making news in science this week

[00:16:11] with the science report. New research warns that older adults who begin losing their sense

[00:16:16] of smell could be more likely to also lose their mobility faster. A report in the Journal of the

[00:16:22] American Medical Association tested the sense of smell of 2,500 people aged between 70 and 79

[00:16:30] and they then tested their walking speed on multiple occasions over the next seven years.

[00:16:35] What they found was fascinating. Those with a reduced ability to smell also tended to walk

[00:16:41] slower during their first test and their walking speed declined faster over the coming years compared

[00:16:47] to those without an impaired sense of smell. The researchers say that this shows the loss of

[00:16:52] sense of smell could be a sign that a person is also losing their mobility but more research

[00:16:58] will be needed in order to understand exactly why this link exists.

[00:17:03] Scientists have developed a self-digesting plastic which they say could not only help

[00:17:08] reduce plastic pollution but also strengthen the plastic itself. A report in the Journal of

[00:17:13] Nature Communications claims researchers developed a biodegradable version of the

[00:17:17] commercial plastic polyurethane which is often used for phone cases, footwear and car parts

[00:17:23] that currently has no recycling stream and so it mostly ends up in landfill. The team

[00:17:28] embedded spores of a plastic degrading bacteria, Bacillus subtilis, and genetically engineered the

[00:17:33] bacteria to tolerate the extreme heat needed to produce the plastic. Upon disposal in the

[00:17:39] simulated environment rapid biodegradation of the plastic was triggered by exposure to

[00:17:44] certain nutrients in the compost. The authors found that sporing corporation led to more than

[00:17:49] 90% of plastic degradation within five months and amazingly it also increased the toughness

[00:17:55] of the plastic by about 37% compared to thermoplastic polyurethanes without the spores.

[00:18:02] A new study has found that teens who can possibly spend too much time online and don't

[00:18:07] get enough sleep or exercise are more likely to skip school or miss classes because of

[00:18:12] illness with girls affected by internet addiction more than boys. The findings reported in the

[00:18:18] journal archives of disease in childhood are based on a survey of 86,270 teenagers aged between

[00:18:25] 14 and 16 who were asked about the time they spent online, their family relationships,

[00:18:30] their sleep patterns and their exercise routines. They classified internet usage as an addiction

[00:18:36] if the teens neglected family, friends, study, eating or sleeping in order to spend more time

[00:18:41] online and if they became anxious when they were offline. Overall they found that between

[00:18:47] 3 and 4 percent frequently miss school. They conclude that exist of internet use is linked

[00:18:52] to an increased risk of both truancy and illness related absence but the effect was reduced by

[00:18:57] better sleep and more exercise as well as by better relationships with their parents.

[00:19:02] And of course we all know how well kids and parents get on during those teenage years.

[00:19:08] Apple's announcing its new iPads including a new iPad Pro, a larger iPad Air and new Magic

[00:19:15] Keyboard and Apple Pencil. Now importantly the new iPad Pro will feature the never before seen M4

[00:19:21] chip which is powerful enough to handle many AI capabilities on device rather than in the cloud.

[00:19:26] With the details we're joined by technology editor Alex Zaharov-Royt from techadvice.life.

[00:19:32] This week everyone will be talking about the new iPads and they're meant to come with the

[00:19:35] M4 chips or at least the iPad Pro models anyway. We have the expectation that they will do

[00:19:40] generative AI on device. Now this was all supposed to be announced at the WorldWild

[00:19:44] Developer Conference but because Microsoft is launching its new Snapdragon powered ARM

[00:19:50] laptops later this month, those laptops are said to be as fast as the M3. Obviously

[00:19:55] Apple wants to be right up the front there with its newest Pro devices. Now it's also

[00:19:59] going to have the iPad Air and it will have a 12.9 inch Air so this is a larger

[00:20:04] but cheaper iPad for those who don't want to spend the premium dollars for the M4 powered

[00:20:09] iPad Pro. There's also meant to be a third generation Apple Pencil which will not only

[00:20:13] be squeezable but it'll have chapstick feedback so we get to see what all this means and we

[00:20:19] get to see how much generative AI is being done on device but the new iPads which were

[00:20:23] rumored to come late last year and then rumored to come in February or March they've been

[00:20:27] officially announced to come on in US May the 7th which is May the 8th in Australia

[00:20:31] and by the time people are listening to this podcast it will be all over the news all of

[00:20:35] each other will be confirmed but they should be very exciting iPads and Apple's throwing

[00:20:40] down the gauntlet to the rest of the industry who has finally caught up with ARM powered

[00:20:45] chips that can run Windows with the same super long battery life no need for a calling fan

[00:20:50] the same sort of benefits that Apple had already back in 2020. The Windows world was

[00:20:54] caught up but Apple is already striving ahead with better chips and later this year we'll

[00:20:58] have the MacBook Airs and the Pros with the M4 and we'll have the new iPhones as well but

[00:21:02] yeah big excitement for what Apple is going to launch and by the time you hear this it

[00:21:05] should all be official. That's Alex Zaharov-Royt from techadvice.life and that's the show for now.

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