S27E109: Venus's Continental Mysteries, BepiColombo's Propulsion Woes, and Sentinel-2C's Orbital Debut

[00:00:00] [SPEAKER_01]: This is SpaceTime Series 27 Episode 109, for broadcast on the 9th of September 2024.

[00:00:06] [SPEAKER_01]: Coming up on SpaceTime…

[00:00:08] [SPEAKER_01]: How Venus got its continents?

[00:00:11] [SPEAKER_01]: Propulsion glitches aboard the BepiColombos spacecraft?

[00:00:14] [SPEAKER_01]: And the Sentinel-2C spacecraft joins the Copernicus family in orbit?

[00:00:19] [SPEAKER_01]: All that and more coming up on SpaceTime.

[00:00:23] [SPEAKER_00]: Welcome to SpaceTime with Stuart Gary.

[00:00:42] [SPEAKER_01]: A new study claims geologic features on the planet Venus known as Tesserae may have formed

[00:00:47] [SPEAKER_01]: in the same way as Earth's earliest continents billions of years ago.

[00:00:52] [SPEAKER_01]: The findings, reported in the journal Nature Geoscience, are based on high-performance

[00:00:56] [SPEAKER_01]: computer simulations as well as data from NASA's Magellan spacecraft.

[00:01:01] [SPEAKER_01]: The results suggest that Ishtar Terra and other Tesserae on Venus may have arisen from

[00:01:07] [SPEAKER_01]: the planet's hot interior through a process very similar to the formation of Earth's cratons,

[00:01:12] [SPEAKER_01]: the ancient cores of continents.

[00:01:14] [SPEAKER_01]: The study's lead author, Associate Professor Fabio Capitano from Monash University,

[00:01:19] [SPEAKER_01]: says the study challenges science's current understandings of how planets evolve.

[00:01:24] [SPEAKER_01]: Capitano says he didn't expect Venus, with its scorching 460-degree surface temperatures

[00:01:29] [SPEAKER_01]: and lack of plate tectonics, to possess such complex geological features.

[00:01:34] [SPEAKER_01]: And so these findings are providing a fascinating new perspective on the planet Venus

[00:01:39] [SPEAKER_01]: and its potential links to the early Earth.

[00:01:42] [SPEAKER_01]: The features found on Venus are strikingly similar to the Earth's early continents.

[00:01:46] [SPEAKER_01]: That suggests that the dynamics of Venus' past may have been far more similar to Earth

[00:01:51] [SPEAKER_01]: than previously thought.

[00:01:53] [SPEAKER_01]: Earth's cratons hold crucial clues about the emergence of topography,

[00:01:57] [SPEAKER_01]: atmosphere and even life on this planet.

[00:01:59] [SPEAKER_01]: Capitano says understanding how these continents formed on Venus could shed fresh light on the

[00:02:05] [SPEAKER_01]: evolution of all rocky planets, including the Earth.

[00:04:36] [SPEAKER_01]: So Venus being so hot, the current theory is that plate tectonics never occurred on Venus?

[00:04:59] [SPEAKER_06]: Capitano says that the Earth's cratons were formed by magmatic processes that extract

[00:05:03] [SPEAKER_06]: the lightest material from the mantle to form continental crust and continental lithosphere.

[00:05:09] [SPEAKER_06]: The point is that they only formed in a period of the Earth,

[00:05:13] [SPEAKER_06]: and didn't form when we know the plate tectonics was operating.

[00:05:17] [SPEAKER_06]: So this raises the question, if plate tectonics is the only mechanism we know,

[00:05:21] [SPEAKER_06]: and it doesn't create continents, so either we extract the theory of plate tectonics to include

[00:05:26] [SPEAKER_06]: formation of cratons, and that didn't work, or otherwise we have to admit that the Earth had

[00:05:32] [SPEAKER_06]: probably a regime that wasn't a plate tectonic regime.

[00:05:35] [SPEAKER_06]: So the work that we've done a few years ago was published in Nature too,

[00:05:39] [SPEAKER_06]: on the formation of cratons is just showing the formation of cratons, as you were saying before,

[00:05:44] [SPEAKER_06]: from convection, but not necessarily plate tectonics.

[00:05:47] [SPEAKER_06]: So you need convection, you need the thinning of lithosphere and melting,

[00:05:51] [SPEAKER_06]: and that melting will create a lot of continental crust,

[00:05:53] [SPEAKER_06]: and the continental crust eventually stays there, as opposed to current plate tectonics,

[00:05:58] [SPEAKER_06]: which every 200 million years material is recycled.

[00:06:01] [SPEAKER_01]: What causes cratons?

[00:06:03] [SPEAKER_01]: What makes a big chunk of the mantle decide to suddenly rise up to the surface?

[00:06:07] [SPEAKER_01]: Is that simply the chemistry involved, and the temperatures and pressures involved

[00:06:12] [SPEAKER_01]: that allow these things to expand upwards?

[00:06:14] [SPEAKER_01]: What causes them?

[00:06:16] [SPEAKER_06]: Well, as you said before, it's one of those ingredients,

[00:06:18] [SPEAKER_06]: and to our understanding, the key ingredient would be the temperature.

[00:06:23] [SPEAKER_06]: We know that the Earth's mantle was hotter in the past,

[00:06:27] [SPEAKER_06]: and when the mantle is hotter, it simply means that the lithosphere that sits on top

[00:06:30] [SPEAKER_06]: is a little bit more cushy or sluggish, it moves a little bit more,

[00:06:35] [SPEAKER_06]: it's a bit more prone to deformation.

[00:06:37] [SPEAKER_06]: And this fact induces the lithosphere to stretch a lot

[00:06:41] [SPEAKER_06]: and allow hot mantle to come up closer to the surface than today.

[00:06:46] [SPEAKER_06]: And when it comes closer to the surface,

[00:06:47] [SPEAKER_06]: it undergoes what is called decompression melting.

[00:06:50] [SPEAKER_06]: So essentially it's very hot, reduces the pressure and melts.

[00:06:54] [SPEAKER_06]: This, of course, imagine that would have been the regime of the whole planet,

[00:06:58] [SPEAKER_06]: it would have created a lot of these large portions of this mantle

[00:07:02] [SPEAKER_06]: decompressing and creating crust.

[00:07:04] [SPEAKER_06]: But the point is also that this melt extracted from the mantle

[00:07:08] [SPEAKER_06]: leaves the mantle depleted.

[00:07:10] [SPEAKER_06]: And when it's depleted, it becomes stiffer and becomes lighter,

[00:07:13] [SPEAKER_06]: like any material that is devoid or depleted of some component.

[00:07:18] [SPEAKER_06]: Imagine a sponge that is depleted of the water,

[00:07:20] [SPEAKER_06]: you're left with the sponge itself, which is inherently lighter.

[00:07:25] [SPEAKER_06]: So that's the mechanism that could work under those conditions

[00:07:28] [SPEAKER_06]: because the Earth was hotter,

[00:07:30] [SPEAKER_06]: and then eventually with secular cooling,

[00:07:31] [SPEAKER_06]: the condition vanished, mantle became cooler and cooler,

[00:07:36] [SPEAKER_06]: and that amount of melting is not possible anymore.

[00:07:39] [SPEAKER_06]: And these are the stages where we think plate tectonics would have started.

[00:07:42] [SPEAKER_01]: Of course, the surface of Venus, 460 degrees Celsius,

[00:07:46] [SPEAKER_01]: is still very hot and malleable.

[00:07:48] [SPEAKER_01]: You've looked at Ishtar Terra, one of the continental Tesserae,

[00:07:52] [SPEAKER_01]: and you focused on that.

[00:07:54] [SPEAKER_01]: Tell me about that.

[00:07:54] [SPEAKER_06]: Yeah, of course, it's an amazing...

[00:07:58] [SPEAKER_06]: We had a look at how this continent forms on Earth,

[00:08:01] [SPEAKER_06]: and the point of the continents is that because, as you say,

[00:08:04] [SPEAKER_06]: they have a crust, the continental crust,

[00:08:06] [SPEAKER_06]: which is inherently lighter because it's extracted from the mantle,

[00:08:08] [SPEAKER_06]: because it's lighter than Moia and thick above the sea level,

[00:08:13] [SPEAKER_06]: whereas the basaltic crust on this planet is heavier and sinks.

[00:08:17] [SPEAKER_06]: So if you don't have this dichotomy,

[00:08:19] [SPEAKER_06]: if you don't have this basaltic crust versus granitic crust,

[00:08:22] [SPEAKER_06]: how do you create topography in the first place,

[00:08:24] [SPEAKER_06]: in places like Venus?

[00:08:26] [SPEAKER_06]: So that's what captured our attention.

[00:08:29] [SPEAKER_06]: So we said, okay, continents on Earth are the places

[00:08:31] [SPEAKER_06]: where elevation increases

[00:08:34] [SPEAKER_06]: and they're led eventually to conditions for life.

[00:08:37] [SPEAKER_06]: Must be the same on Venus.

[00:08:40] [SPEAKER_06]: So they are above these plateaus, these elevated areas.

[00:08:45] [SPEAKER_06]: They are standing above the average radius of the planet

[00:08:49] [SPEAKER_06]: because they must be lighter.

[00:08:51] [SPEAKER_06]: And if they're lighter, we have to find a mechanism that creates that.

[00:08:54] [SPEAKER_06]: So we had a lot of observation and a lot of work

[00:08:57] [SPEAKER_06]: that was done interpreting those observations.

[00:08:59] [SPEAKER_06]: But so far, we never had a forward model.

[00:09:02] [SPEAKER_06]: So a model that starts with the fundamental principles of physics,

[00:09:06] [SPEAKER_06]: the physics that we use in geology,

[00:09:08] [SPEAKER_06]: and then eventually leads to the formation of these plateaus.

[00:09:11] [SPEAKER_06]: So eventually we came to the conclusion that,

[00:09:13] [SPEAKER_06]: yes, we don't have an ocean here,

[00:09:15] [SPEAKER_06]: we don't have a basaltic crust,

[00:09:16] [SPEAKER_06]: but those areas, they have a thick, lighter crust

[00:09:19] [SPEAKER_06]: formed in the same way of cratons and eventually they pop up.

[00:09:22] [SPEAKER_01]: So cratons is it?

[00:09:23] [SPEAKER_06]: Yeah, yeah, yeah.

[00:09:24] [SPEAKER_06]: Besides, as I said, we have to change name

[00:09:26] [SPEAKER_06]: because we call those on Venus plateaus,

[00:09:29] [SPEAKER_06]: but plateaus on this planet are places like Tibet.

[00:09:32] [SPEAKER_06]: So we probably should call it rather Nishitaterra Plateau,

[00:09:35] [SPEAKER_06]: Nishitaterra Craton.

[00:09:36] [SPEAKER_01]: There are some features on the surface of Venus

[00:09:39] [SPEAKER_01]: that we just don't see here on Earth.

[00:09:41] [SPEAKER_06]: No, no, there's many, many out there.

[00:09:44] [SPEAKER_06]: One of those is volcanoes that are incredibly taller

[00:09:48] [SPEAKER_06]: than other planets on Earth.

[00:09:52] [SPEAKER_06]: The same itself, the same Nishitaterra,

[00:09:54] [SPEAKER_06]: that's why it captured our attention,

[00:09:57] [SPEAKER_06]: is it is called a plateau,

[00:09:59] [SPEAKER_06]: but if you think about it,

[00:10:00] [SPEAKER_06]: it's as tall as the Malaya,

[00:10:03] [SPEAKER_06]: as the Tibetan plateau,

[00:10:06] [SPEAKER_06]: has some bordering mountains that are as tall as the Malaya

[00:10:09] [SPEAKER_06]: and even taller.

[00:10:10] [SPEAKER_06]: So the Maxwell Mount reaches up to 13 kilometers

[00:10:13] [SPEAKER_06]: as opposed to the less than nine of the Malaya.

[00:10:16] [SPEAKER_06]: So you can imagine how tall it is.

[00:10:18] [SPEAKER_06]: And also the size of the width of that plateau

[00:10:21] [SPEAKER_06]: is essentially as big as Australia.

[00:10:24] [SPEAKER_06]: So we don't see such big, incredibly big continents

[00:10:28] [SPEAKER_06]: formed in the same way

[00:10:30] [SPEAKER_06]: because Australia is quite big,

[00:10:31] [SPEAKER_06]: doesn't have the topography

[00:10:32] [SPEAKER_06]: and Australia is just a puzzle of different pieces.

[00:10:36] [SPEAKER_06]: So they don't fall together like happen on Venus.

[00:10:39] [SPEAKER_01]: Where do you take this research to now?

[00:10:41] [SPEAKER_06]: This research that we do in the evolution of the planet

[00:10:43] [SPEAKER_06]: compared to the Earth has an obvious application.

[00:10:47] [SPEAKER_06]: If you consider that the evolution of our planet

[00:10:49] [SPEAKER_06]: led to the condition for life,

[00:10:51] [SPEAKER_06]: the way we understand whether there is life on other planets

[00:10:54] [SPEAKER_06]: is essentially looking at their tectonic evolution.

[00:10:57] [SPEAKER_01]: That's Associate Professor Fabio Capitanio

[00:10:59] [SPEAKER_01]: from Monash University.

[00:11:02] [SPEAKER_01]: And this is Space Time.

[00:11:04] [SPEAKER_01]: Still to come, a propulsion glitz

[00:11:06] [SPEAKER_01]: aboard the BepiColombo spacecraft

[00:11:08] [SPEAKER_01]: and the European Space Agency's Sentinel-2C spacecraft

[00:11:11] [SPEAKER_01]: joins the Copernicus family in orbit.

[00:11:14] [SPEAKER_01]: All that and more still to come on Space Time.

[00:11:32] [SPEAKER_01]: Mission managers on the BepiColombo spacecraft

[00:11:35] [SPEAKER_01]: are working to resolve a problem

[00:11:37] [SPEAKER_01]: which has been affecting the spacecraft's thrusters.

[00:11:40] [SPEAKER_01]: The issue is preventing the thrusters

[00:11:42] [SPEAKER_01]: aboard the joint European Space Agency-Japan Aerospace Exploration Agency probe

[00:11:47] [SPEAKER_01]: from operating at full thrust.

[00:11:49] [SPEAKER_01]: BepiColombo is a three-part spacecraft.

[00:11:52] [SPEAKER_01]: It consists of two science orbiters,

[00:11:54] [SPEAKER_01]: ESA's Mercury Planetary Orbiter

[00:11:56] [SPEAKER_01]: and JAXA's Mercury Magnetospheric Orbiter,

[00:11:59] [SPEAKER_01]: as well as a cruise and propulsion stage

[00:12:02] [SPEAKER_01]: known as the Mercury Transfer Module.

[00:12:04] [SPEAKER_01]: The two scientific vehicles are designed to separate from one another

[00:12:08] [SPEAKER_01]: during Mercury orbit insertion,

[00:12:09] [SPEAKER_01]: allowing them to investigate different aspects of the planet

[00:12:12] [SPEAKER_01]: from different orbits.

[00:12:14] [SPEAKER_01]: The solar arrays and electrical propulsion systems

[00:12:17] [SPEAKER_01]: on the Mercury Transfer Module

[00:12:18] [SPEAKER_01]: are used to generate thrust

[00:12:20] [SPEAKER_01]: during the spacecraft's complex journey from Earth

[00:12:23] [SPEAKER_01]: to the nearest rock to the Sun.

[00:12:25] [SPEAKER_01]: However, on April 26th,

[00:12:27] [SPEAKER_01]: as BepiColombo was preparing to begin its next orbital manoeuvre,

[00:12:30] [SPEAKER_01]: the Transfer Module failed to deliver enough electrical power

[00:12:34] [SPEAKER_01]: to the spacecraft's ion propulsion thrusters.

[00:12:36] [SPEAKER_01]: Eventually, engineers identified unexpected electrical currents

[00:12:40] [SPEAKER_01]: between the Mercury Transfer Module's solar arrays

[00:12:43] [SPEAKER_01]: and the units responsible for extracting power

[00:12:45] [SPEAKER_01]: and then distributing it to the rest of the spacecraft.

[00:12:48] [SPEAKER_01]: Technicians were able to restore about 90% of that power by May 7th,

[00:12:53] [SPEAKER_01]: but they've failed to achieve full thrust.

[00:12:56] [SPEAKER_01]: Mission managers have now developed a workaround

[00:12:58] [SPEAKER_01]: to account for the spacecraft's reduced power.

[00:13:01] [SPEAKER_01]: The new trajectory maintains the baseline scientific mission,

[00:13:05] [SPEAKER_01]: but it allows the spacecraft to use lower thrust settings

[00:13:08] [SPEAKER_01]: during the cruise phase of the mission.

[00:13:10] [SPEAKER_01]: With this new trajectory,

[00:13:12] [SPEAKER_01]: BepiColombo is now expected to arrive at Mercury in November 2026.

[00:13:16] [SPEAKER_01]: That's 13 months later than originally expected.

[00:13:20] [SPEAKER_01]: The BepiColombo flight control team's current priorities

[00:13:23] [SPEAKER_01]: are to maintain stable spacecraft propulsion

[00:13:26] [SPEAKER_01]: at the currently available power level

[00:13:28] [SPEAKER_01]: and to determine how this will affect future operations.

[00:13:32] [SPEAKER_01]: The good news is BepiColombo did arrive at Mercury

[00:13:35] [SPEAKER_01]: in time for its fourth gravity assist flyby around the planet last week,

[00:13:39] [SPEAKER_01]: swooping down at just 165 kilometres above the Mercury in surface.

[00:13:44] [SPEAKER_01]: The close encounter took BepiColombo closer to Mercury

[00:13:47] [SPEAKER_01]: than it's ever been before,

[00:13:49] [SPEAKER_01]: in the process reducing the spacecraft's speed and changing its direction.

[00:13:53] [SPEAKER_01]: It also gave mission managers a chance to snap some amazing images of the planet

[00:13:57] [SPEAKER_01]: and fine-tune science instrument operations before the main mission begins.

[00:14:03] [SPEAKER_01]: BepiColombo was launched in October 2018.

[00:14:06] [SPEAKER_01]: It's on a trajectory that makes use of nine planetary flybys.

[00:14:10] [SPEAKER_01]: These include one of the Earth, two of Venus and six of planet Mercury itself.

[00:14:15] [SPEAKER_01]: These are all needed to help steer the probe into orbit around the planet.

[00:14:20] [SPEAKER_01]: BepiColombo's fifth Mercury flyby will occur in December,

[00:14:23] [SPEAKER_01]: followed by a sixth in January.

[00:14:26] [SPEAKER_01]: After that, the probe should be able to achieve Mercury orbit insertion.

[00:14:29] [SPEAKER_01]: The planet Mercury is the least explored planet in the inner solar system.

[00:14:35] [SPEAKER_01]: That's mainly because getting there is a real challenge.

[00:14:38] [SPEAKER_01]: See, as a spacecraft gets closer to the Sun,

[00:14:40] [SPEAKER_01]: the powerful gravitational pull of our local star

[00:14:43] [SPEAKER_01]: tends to accelerate that spacecraft towards it.

[00:14:46] [SPEAKER_01]: Now add to that the fact that any spacecraft launched from Earth

[00:14:49] [SPEAKER_01]: already has lots of energy needed to escape Earth's gravity,

[00:14:52] [SPEAKER_01]: it winds up travelling much too quickly

[00:14:55] [SPEAKER_01]: to be captured in orbit around little Mercury by itself.

[00:14:58] [SPEAKER_01]: To overcome these hurdles would be enormously difficult using just on-board thrusters.

[00:15:04] [SPEAKER_01]: So BepiColombo also makes use of gravity assist flybys.

[00:15:08] [SPEAKER_01]: These help it lose energy and slow down enough

[00:15:11] [SPEAKER_01]: to eventually be captured by Mercury's gravity and enter orbit.

[00:15:15] [SPEAKER_01]: Ten of BepiColombo's 16 science instruments were operational during last week's flyby.

[00:15:21] [SPEAKER_01]: That gave scientists a chance to taste the sort of discoveries

[00:15:24] [SPEAKER_01]: they can expect to make once the main mission begins.

[00:15:27] [SPEAKER_01]: Magnetic, plasma and particle monitoring instruments

[00:15:30] [SPEAKER_01]: sampled the environment before, during and after the closest approach.

[00:15:35] [SPEAKER_01]: Other instruments couldn't be operated

[00:15:36] [SPEAKER_01]: because their fields of view were blocked by the Mercury Transfer Module.

[00:15:40] [SPEAKER_01]: Testing out the instruments during flybys

[00:15:42] [SPEAKER_01]: provides a valuable opportunity for science teams to check their instruments,

[00:15:47] [SPEAKER_01]: make sure they're functioning properly

[00:15:48] [SPEAKER_01]: and that they've been calibrated correctly for the main mission.

[00:15:52] [SPEAKER_01]: Now sadly, BepiColombo's main science camera will be shielded

[00:15:55] [SPEAKER_01]: until the ESA and JAXA orbiters separate.

[00:15:58] [SPEAKER_01]: But during the flybys, images have been taken

[00:16:00] [SPEAKER_01]: using three monitoring cameras on the Mercury Transfer Vehicle.

[00:16:04] [SPEAKER_01]: These are providing black and white snapshots.

[00:16:08] [SPEAKER_01]: The cameras are actually designed to monitor the spacecraft's solar arrays,

[00:16:11] [SPEAKER_01]: its antenna and its magnetometer boom,

[00:16:14] [SPEAKER_01]: especially during the challenging period after launch.

[00:16:17] [SPEAKER_01]: Last week's flyby was also the first to take BepiColombo over Mercury's poles,

[00:16:22] [SPEAKER_01]: helping to adjust the spacecraft's trajectory to match that of Mercury,

[00:16:25] [SPEAKER_01]: which is inclined compared to the Earth's orbit.

[00:16:28] [SPEAKER_01]: The images include the first ever stunning views of the planet's south pole.

[00:16:32] [SPEAKER_01]: Others reveal large craters, wrinkle ridges and lava plains,

[00:16:36] [SPEAKER_01]: all of which are helping scientists better unlock the secrets

[00:16:39] [SPEAKER_01]: of Mercury's 4.6 billion year history

[00:16:41] [SPEAKER_01]: and its place in the evolution of our solar system.

[00:16:45] [SPEAKER_01]: This report from ESA TV.

[00:16:52] [SPEAKER_07]: The BepiColombo mission to Mercury is off to a successful start.

[00:17:00] [SPEAKER_07]: Within hours of launching from the European spaceport in French Guiana,

[00:17:05] [SPEAKER_07]: the spacecraft had unfurled its antennas and two 15-metre solar arrays.

[00:17:12] [SPEAKER_07]: Monitoring cameras even took some selfies,

[00:17:15] [SPEAKER_07]: showing one of the solar panels and two antennas.

[00:17:19] [SPEAKER_07]: A few days later, the spacecraft deployed a three-metre boom

[00:17:23] [SPEAKER_07]: containing sensors to record magnetic fields.

[00:17:27] [SPEAKER_07]: Images from the NASA Messenger mission are the best we have of Mercury.

[00:17:32] [SPEAKER_07]: It has highlands and lowlands like other planets,

[00:17:35] [SPEAKER_07]: but unlike Earth, Mercury rotates on an axis perpendicular to its orbit.

[00:17:42] [SPEAKER_02]: Due to the fact that Mercury is not tilted,

[00:17:45] [SPEAKER_02]: there are some craters on the poles where the sun never shines into it.

[00:17:51] [SPEAKER_02]: And inside these craters, Messenger found water ice.

[00:17:56] [SPEAKER_02]: It was detected even earlier in the 80s from ground

[00:18:00] [SPEAKER_02]: that there were rather bright spots and there were some hints

[00:18:03] [SPEAKER_02]: that it might be water ice.

[00:18:05] [SPEAKER_02]: But now from Messenger, we are pretty sure that we have water ice in craters.

[00:18:11] [SPEAKER_02]: And that's pretty much surprising.

[00:18:13] [SPEAKER_02]: Think about it.

[00:18:14] [SPEAKER_02]: If you have a planet on the surface 450 degrees

[00:18:17] [SPEAKER_02]: and then you have water ice at the poles, it's kind of unbelievable.

[00:18:22] [SPEAKER_07]: Fortunately, there's an instrument on board called MERTIS,

[00:18:25] [SPEAKER_07]: which can measure the surface temperature directly

[00:18:28] [SPEAKER_07]: to see if it's cold enough for water ice.

[00:18:32] [SPEAKER_07]: Knowing the make-up of the planet's dark surface is also important.

[00:18:37] [SPEAKER_07]: A team at DLR, the German space agency,

[00:18:40] [SPEAKER_07]: have built a special chamber to heat up samples

[00:18:44] [SPEAKER_07]: to examine how they behave at high temperatures.

[00:18:48] [SPEAKER_07]: These can then be compared with what will be found on the planet.

[00:18:53] [SPEAKER_07]: Planetary scientists are unsure how it formed.

[00:18:57] [SPEAKER_07]: It could have originated beyond Mars,

[00:18:59] [SPEAKER_07]: with an impact pushing it closer to the sun.

[00:19:02] [SPEAKER_07]: Or it could have formed at lower temperatures in its current position.

[00:19:07] [SPEAKER_07]: If so, current theoretical models will need a rethink.

[00:19:12] [SPEAKER_05]: One of the things why I like working on Mercury

[00:19:15] [SPEAKER_05]: is we need to understand Mercury in order to understand how planets form.

[00:19:20] [SPEAKER_05]: If we have a model that forms all planets but not Mercury,

[00:19:25] [SPEAKER_05]: that model is basically useless because you need to get that one as well.

[00:19:29] [SPEAKER_07]: NASA's Messenger mission did a great job.

[00:19:32] [SPEAKER_07]: But Bebicolombo consists of two orbiters

[00:19:35] [SPEAKER_07]: using complementary orbits with more combined instruments.

[00:19:41] [SPEAKER_07]: Plus, unlike Messenger,

[00:19:43] [SPEAKER_07]: it will obtain high-resolution images of the entire planet.

[00:19:48] [SPEAKER_07]: The planet is also shrinking in size, possibly due to cooling.

[00:19:53] [SPEAKER_07]: Plus there may be active volcanoes, so there is much more to learn.

[00:19:58] [SPEAKER_02]: Mercury is a very mysterious planet.

[00:20:01] [SPEAKER_02]: Every time we went there, we found new surprising results.

[00:20:05] [SPEAKER_02]: That is the reason why we do Bebicolombo.

[00:20:08] [SPEAKER_02]: We hope with Bebicolombo, on one hand,

[00:20:10] [SPEAKER_02]: we are able to answer many of these new questions.

[00:20:14] [SPEAKER_02]: But I'm pretty sure we found a lot of new surprising results

[00:20:18] [SPEAKER_02]: which raise new and other questions which we then need to follow up.

[00:20:24] [SPEAKER_01]: And in that report from ESA TV,

[00:20:26] [SPEAKER_01]: we heard from Bebicolombo ESA Project scientist Johannes Benckhoff

[00:20:29] [SPEAKER_01]: and DLR planetary scientist Jorn Hilbert.

[00:20:33] [SPEAKER_01]: This is Space Time.

[00:20:35] [SPEAKER_01]: Still to come,

[00:20:37] [SPEAKER_01]: Sentinel-2C joins the Copernicus family in orbit following a successful liftoff.

[00:20:41] [SPEAKER_01]: And later in the Science Report,

[00:20:43] [SPEAKER_01]: a new mega study confirms what we've been telling you for years.

[00:20:47] [SPEAKER_01]: Cell phones don't cause brain cancer.

[00:20:50] [SPEAKER_01]: All that and more still to come on Space Time.

[00:21:09] [SPEAKER_01]: The third European Space Agency Sentinel-2 satellite

[00:21:12] [SPEAKER_01]: has been successfully launched into orbit.

[00:21:15] [SPEAKER_01]: The flight was aboard the very last Vega rocket

[00:21:18] [SPEAKER_01]: from the European Space Agency's Kourou Spaceport in French Guiana.

[00:21:22] [SPEAKER_04]: We have a fixed launch time today.

[00:21:23] [SPEAKER_04]: We don't have a launch window.

[00:21:25] [SPEAKER_04]: We're live at the European Spaceport in French Guiana

[00:21:28] [SPEAKER_04]: for the launch of Sentinel-2C.

[00:21:30] [SPEAKER_04]: Our very best wishes to all the teams.

[00:21:32] [SPEAKER_09]: Go Sentinel-2C.

[00:21:45] [SPEAKER_04]: They're off.

[00:21:46] [SPEAKER_04]: Sentinel-2C and Vega are blazing a trail

[00:21:49] [SPEAKER_04]: across the equatorial skies here over Europe's spaceport in French Guiana,

[00:21:54] [SPEAKER_04]: heading north out over the Atlantic towards the Caribbean islands,

[00:21:59] [SPEAKER_04]: burning the first three stages.

[00:22:00] [SPEAKER_04]: The first stage, of course, burning now,

[00:22:02] [SPEAKER_04]: getting us away from the gravity of the Earth.

[00:22:06] [SPEAKER_04]: Vega really shoots into the sky, Damien, doesn't she?

[00:22:09] [SPEAKER_09]: Yeah, it does.

[00:22:09] [SPEAKER_09]: It does.

[00:22:10] [SPEAKER_09]: And we could feel the rumble tumble here in the commentary cabin.

[00:22:13] [SPEAKER_09]: So the P-80 delivers a powerful thrust,

[00:22:16] [SPEAKER_09]: about 230 tonnes, equivalent to twice its weight.

[00:22:20] [SPEAKER_09]: It just results in a very rapid acceleration.

[00:22:22] [SPEAKER_09]: So the first stage, its mass in propellants is 89 tonnes,

[00:22:26] [SPEAKER_09]: and it is made of a special material called filament-wound carbon epoxy.

[00:22:31] [SPEAKER_04]: And separation there of the P-80 first stage

[00:22:35] [SPEAKER_04]: and switch on of the second stage, the Z-23.

[00:22:41] [SPEAKER_04]: So at this point in time, we've lost about two thirds of our weight

[00:22:45] [SPEAKER_04]: and we're hearing that the propulsion is nominal

[00:22:48] [SPEAKER_04]: and the trajectory is nominal.

[00:22:49] [SPEAKER_04]: And of course, the idea is to get rid of mass when it's no longer needed.

[00:22:53] [SPEAKER_09]: As soon as each solid stage has used its propellant, yes, we jettison it.

[00:22:57] [SPEAKER_09]: So that's why we split the rocket into different stages

[00:23:00] [SPEAKER_09]: to avoid dragging unnecessary mass into space.

[00:23:03] [SPEAKER_04]: And we're burning the Z-23 second stage, Z for Zephyro,

[00:23:08] [SPEAKER_04]: which is a type of wind, a gentle and favourable west wind.

[00:23:12] [SPEAKER_09]: It is often associated with bringing spread and good weather.

[00:23:15] [SPEAKER_09]: It very much aligns with the goal of the Vega launcher,

[00:23:18] [SPEAKER_09]: which aims at providing reliable and efficient access to space.

[00:23:22] [SPEAKER_09]: So Katie, it's a poetic note to the idea of a smooth and successful journey.

[00:23:27] [SPEAKER_04]: And we're getting news that coming towards the end of the burning of the Z-23,

[00:23:33] [SPEAKER_04]: our altitude 113 kilometres above the Earth,

[00:23:37] [SPEAKER_04]: travelling at nearly four kilometres per second.

[00:23:39] [SPEAKER_04]: Separation there of the second stage.

[00:23:42] [SPEAKER_04]: And there's a short delay before we then get the ignition of the third stage.

[00:23:47] [SPEAKER_04]: That's to avoid any collisions up in space.

[00:23:49] [SPEAKER_04]: And we have separation now of the fairing that's been jettisoned.

[00:23:53] [SPEAKER_04]: We don't need it anymore.

[00:23:54] [SPEAKER_04]: And we've got the switch on time.

[00:23:57] [SPEAKER_04]: Now, this is the scheduled moment to switch on the engine of the Avum upper stage.

[00:24:01] [SPEAKER_04]: We have that confirmed.

[00:24:03] [SPEAKER_04]: This is an important moment, actually, in the flight trajectory is nominal.

[00:24:07] [SPEAKER_04]: We're hearing we've really started the next phase now of this part of the journey

[00:24:11] [SPEAKER_04]: because the Avum or Avum has taken the wheel

[00:24:14] [SPEAKER_04]: and its job is to deliver our passenger to its required orbit.

[00:24:18] [SPEAKER_04]: Yeah, we've got confirmation.

[00:24:20] [SPEAKER_04]: Confirmation, yeah.

[00:24:22] [SPEAKER_04]: We have a switch on of the second boost for the Avum upper stage.

[00:24:29] [SPEAKER_04]: It's switched its engine on again.

[00:24:31] [SPEAKER_04]: All going according to plan, all nominal coming up now on Avum cutoff.

[00:24:39] [SPEAKER_04]: And we have confirmation there.

[00:24:41] [SPEAKER_04]: Second switching off of the Avum upper stage confirmed.

[00:24:45] [SPEAKER_04]: We're on the targeted injection orbit required for Sentinel-2C.

[00:24:49] [SPEAKER_04]: The separation actually is going to start pretty soon now.

[00:24:51] [SPEAKER_00]: In a matter of seconds.

[00:24:53] [SPEAKER_04]: And he's telling us that the orbit is completely nominal.

[00:25:00] [SPEAKER_04]: Beginning of the orientation maneuver,

[00:25:02] [SPEAKER_04]: getting Sentinel-2C ready to be released onto its orbit.

[00:25:07] [SPEAKER_09]: Departure Sentinel-2C.

[00:25:09] [SPEAKER_04]: You have separation there of Sentinel-2C.

[00:25:12] [SPEAKER_04]: That's good news.

[00:25:14] [SPEAKER_04]: We are looking at happy faces in the mission control center here,

[00:25:19] [SPEAKER_04]: Jupiter Mission Control Center.

[00:25:21] [SPEAKER_01]: Sentinel-2C will provide high resolution data as part of the Copernicus Earth Observation Program,

[00:25:28] [SPEAKER_01]: monitoring climate change and environmental challenges globally.

[00:25:32] [SPEAKER_01]: It'll ensure the continuity of vital data

[00:25:34] [SPEAKER_01]: in support of agricultural, forestry, maritime and pollution monitoring.

[00:25:39] [SPEAKER_01]: Two previous Sentinel-2 satellites, Sentinel-2A and Sentinel-2B,

[00:25:43] [SPEAKER_01]: were launched back in 2015 and 2017 respectively, both using Vega rockets.

[00:25:49] [SPEAKER_01]: Sentinel-2C marked the final liftoff for the Vega rocket.

[00:25:53] [SPEAKER_01]: All future Vega launches will now use the new upgraded Vega-C.

[00:25:58] [SPEAKER_01]: The Copernicus Sentinel-2 mission provides high resolution optical imagery for land,

[00:26:03] [SPEAKER_01]: water and atmospheric monitoring.

[00:26:05] [SPEAKER_01]: The mission is based on a constellation of two identical satellites flying in the same orbit 180

[00:26:11] [SPEAKER_01]: degrees apart.

[00:26:12] [SPEAKER_01]: Currently, they are Sentinel-2A and Sentinel-2B.

[00:26:16] [SPEAKER_01]: Together they cover the entire planet's land and coastal waters every five days.

[00:26:21] [SPEAKER_01]: With Sentinel-2C now in orbit, it'll soon replace its predecessor Sentinel-2A

[00:26:26] [SPEAKER_01]: following a brief period of tandem observations.

[00:26:29] [SPEAKER_01]: Eventually a fourth satellite, Sentinel-2D, will be launched to take over from Sentinel-2B.

[00:26:35] [SPEAKER_01]: Later it's planned that the Sentinel-2 Next Generation mission will ensure data continuity

[00:26:40] [SPEAKER_01]: beyond 2035.

[00:26:42] [SPEAKER_01]: The current Sentinel-2 satellites each carry a high resolution multispectral imager which

[00:26:47] [SPEAKER_01]: generates optical images in the visible, near-infrared and shortwave infrared part

[00:26:52] [SPEAKER_01]: of the electromagnetic spectrum.

[00:26:54] [SPEAKER_01]: From their 786 km high orbit, they provide continuous imagery in 13 spectral bands with

[00:27:01] [SPEAKER_01]: resolutions of 10 metres, 20 metres and 60 metres and a wide survey width of 290 kilometres.

[00:27:09] [SPEAKER_01]: Sentinel-2 data is currently being used for agriculture, water quality monitoring and

[00:27:13] [SPEAKER_01]: natural disaster management including wildfires, volcanic eruptions and floods.

[00:27:19] [SPEAKER_01]: The mission's already surpassed its original expectations by demonstrating its ability

[00:27:23] [SPEAKER_01]: to detect emissions of the greenhouse gas methane.

[00:27:27] [SPEAKER_01]: For agriculture, the mission helps monitor crop health, it predicts yield outcome and

[00:27:31] [SPEAKER_01]: it enables precision farming.

[00:27:33] [SPEAKER_01]: The images are being used to detect crop type and to determine biophysical variabilities

[00:27:38] [SPEAKER_01]: such as leaf area, leaf chlorophyll content and water content in order to monitor plant

[00:27:43] [SPEAKER_01]: growth and health.

[00:27:45] [SPEAKER_01]: This report from ESA TV.

[00:27:48] [SPEAKER_08]: Sentinel-2 is based on a constellation of two identical satellites.

[00:27:52] [SPEAKER_08]: Sentinel-2A and Sentinel-2B.

[00:27:56] [SPEAKER_08]: They both fly in the same orbit but apart to optimise coverage and revisit time.

[00:28:02] [SPEAKER_08]: The satellites carry a high resolution multi-spectral imager and generate optical images from the

[00:28:08] [SPEAKER_08]: visible to the shortwave infrared region of the electromagnetic spectrum.

[00:28:14] [SPEAKER_08]: The constellation was originally designed to monitor land surfaces but its scope has

[00:28:19] [SPEAKER_08]: since expanded.

[00:28:21] [SPEAKER_08]: It now covers a wide range of applications.

[00:28:25] [SPEAKER_08]: This includes land cover changes like deforestation, agricultural monitoring and mapping variables

[00:28:31] [SPEAKER_08]: like leaf chlorophyll, leaf area index and water content.

[00:28:37] [SPEAKER_08]: It also monitors water quality, changes in water bodies and coastal erosion.

[00:28:43] [SPEAKER_08]: It has witnessed icebergs breaking, glaciers retreating, ice sheets melting, changes in

[00:28:49] [SPEAKER_08]: sea ice.

[00:28:49] [SPEAKER_08]: And variations in snow cover.

[00:28:53] [SPEAKER_08]: It has even spotted penguin poo from space, helping monitor emperor penguin colonies.

[00:29:01] [SPEAKER_08]: Sentinel-2 has also proved useful in monitoring natural disasters like wildfires, earthquakes,

[00:29:07] [SPEAKER_08]: volcanic eruptions, floods and landslides.

[00:29:11] [SPEAKER_08]: These data feed into the Copernicus Emergency Management Services and the International

[00:29:17] [SPEAKER_08]: Disasters Charter, providing essential imagery to support local teams.

[00:29:24] [SPEAKER_08]: The Sentinel-2 mission even went above and beyond its original expectations, demonstrating

[00:29:29] [SPEAKER_08]: its ability in detecting methane emissions.

[00:29:34] [SPEAKER_08]: Sentinel-2C will replace the Sentinel-2A unit, prolonging the life of the Sentinel-2

[00:29:39] [SPEAKER_08]: mission and ensuring a continuous supply of data for Copernicus, the Earth observation

[00:29:45] [SPEAKER_08]: component of the EU space program.

[00:29:48] [SPEAKER_01]: This is Space Time.

[00:29:53] [SPEAKER_01]: And time now to take a brief look at some of the other stories making use in science

[00:30:09] [SPEAKER_01]: this week with a science report.

[00:30:11] [SPEAKER_01]: A World Health Organization commissioned systematic review of the potential health

[00:30:16] [SPEAKER_01]: effects of radio wave exposure has found that cell phones are not linked to any head cancers.

[00:30:22] [SPEAKER_01]: The findings, reported in the journal Environmental International, looked at over 5,000

[00:30:27] [SPEAKER_01]: individual studies.

[00:30:29] [SPEAKER_01]: Of these, 63 which were published between 1994 and 2022 were included in the final analysis.

[00:30:37] [SPEAKER_01]: Scientists found that although the use of wireless technology has massively increased

[00:30:41] [SPEAKER_01]: in the last 20 years, there has been no increase in the incidence of brain cancers.

[00:30:46] [SPEAKER_01]: The study was led by experts from APANSA, the Australian Radiation Protection and Nuclear

[00:30:51] [SPEAKER_01]: Safety Agency.

[00:30:54] [SPEAKER_01]: A new study claims that more than a third of the world's fish species never received

[00:30:58] [SPEAKER_01]: an extinction threat classification simply because scientists don't know enough about

[00:31:02] [SPEAKER_01]: them.

[00:31:03] [SPEAKER_01]: Now researchers are using artificial intelligence to try and predict which of these thousands

[00:31:08] [SPEAKER_01]: of data deficient species are most at risk.

[00:31:11] [SPEAKER_01]: A report in the journal PLOS One quintuples the number of species in the threatened category,

[00:31:16] [SPEAKER_01]: with Australia's west coast and many Pacific islands being hotspots for the need for protection.

[00:31:24] [SPEAKER_01]: Paleontologists have described a new species of dinosaur which roamed the Iberian Peninsula

[00:31:28] [SPEAKER_01]: 75 million years ago.

[00:31:31] [SPEAKER_01]: Fossils of the 6-metre tall Quincasauro pinnaconiestra were discovered during construction

[00:31:36] [SPEAKER_01]: works on one of Spain's many new high-speed rail lines.

[00:31:39] [SPEAKER_01]: A report in the journal Communications Biology claims the Late Cretaceous ericeropod is one

[00:31:45] [SPEAKER_01]: of the most complete skeletons ever found in Europe, including cervical, dorsal and

[00:31:50] [SPEAKER_01]: caudal vertebrae as well as part of the pelvic girdle and even elements of the limbs.

[00:31:55] [SPEAKER_01]: Ceropods are those large herbivore dinosaurs similar in appearance to Fred Flintstone's

[00:32:00] [SPEAKER_01]: pet Dino.

[00:32:01] [SPEAKER_01]: They have large elephant-like bodies and legs, a long tail at one end and a long neck

[00:32:06] [SPEAKER_01]: and small head at the other.

[00:32:09] [SPEAKER_01]: Well, it sounds like something out of the X-Files, but a group of scientists is seriously

[00:32:14] [SPEAKER_01]: proposing that some UFO sightings could be a secretive population of advanced dinosaur

[00:32:20] [SPEAKER_01]: humanoid beings that evolved from Velociraptors.

[00:32:24] [SPEAKER_01]: Because of their large brains, senior paleontologists have long speculated that had the warm-blooded

[00:32:29] [SPEAKER_01]: Velociraptors survived the extinction of non-avian dinosaurs 66 million years ago,

[00:32:34] [SPEAKER_01]: mammals might still be shrew-like creatures scurrying around the forest floors.

[00:32:39] [SPEAKER_01]: You see, the size of Velociraptor's brain in proportion to its body is relatively high,

[00:32:45] [SPEAKER_01]: especially compared to most other reptiles, including most other dinosaurs, so it seems

[00:32:49] [SPEAKER_01]: likely it was comparatively clever.

[00:32:52] [SPEAKER_01]: And that raises the possibility that, had they survived, they might have eventually

[00:32:56] [SPEAKER_01]: evolved into a species of intelligent humanoids filling the same ecological niche as Homo

[00:33:02] [SPEAKER_01]: sapien does today.

[00:33:04] [SPEAKER_01]: This so-called dinosauroid was a serious hypothetical study based on the evolution of Homo sapiens,

[00:33:11] [SPEAKER_01]: looking at what Statonic Dinosaurus raptors might have eventually become had they continued

[00:33:15] [SPEAKER_01]: to evolve until the present day.

[00:33:18] [SPEAKER_01]: With a larger brain, they would have had a shorter neck and a more upright posture.

[00:33:23] [SPEAKER_01]: That would have been arrived as a way to better balance the head more efficiently.

[00:33:27] [SPEAKER_01]: The vertical posture would also have removed the need for a tail.

[00:33:31] [SPEAKER_01]: The legs were modified simply by lowering the ankle to the ground, and the foot was

[00:33:35] [SPEAKER_01]: lengthened.

[00:33:36] [SPEAKER_01]: But of course all that's just a thought experiment.

[00:33:39] [SPEAKER_01]: The KT Boundary Event asteroid impact at Chicxulub in the Yucatan Peninsula put an end

[00:33:44] [SPEAKER_01]: to that line of evolution.

[00:33:46] [SPEAKER_01]: Or did it?

[00:33:48] [SPEAKER_01]: The new hypothesis by scientists from Harvard University speculates that some unexplained

[00:33:53] [SPEAKER_01]: UFO sightings could actually be signs that these creatures are here.

[00:33:57] [SPEAKER_01]: But as Tim Mendham from Australian Skeptics points out, anything lacking is any kind of

[00:34:02] [SPEAKER_01]: evidence.

[00:34:56] [SPEAKER_03]: Yeah, I don't know how intelligent they are.

[00:34:58] [SPEAKER_03]: But yeah, people have suggested Bigfoot's an alien.

[00:35:01] [SPEAKER_03]: UFO sightings, craft and other phenomena, e.g.

[00:35:04] [SPEAKER_03]: orbs, appearing to enter and exit potential underground access points like volcanoes.

[00:35:09] [SPEAKER_03]: So they're coming in and out, hollow earth, and flying around and then flying back again

[00:35:12] [SPEAKER_03]: to where they were, just to annoy us and confuse us.

[00:35:15] [SPEAKER_01]: I don't know, it all sounds like something Harvey Loeb would write in a thesis.

[00:35:19] [SPEAKER_03]: It does sound like something he would do.

[00:35:20] [SPEAKER_03]: It also sounds like something every science fiction writer would do.

[00:35:23] [SPEAKER_03]: Remember this TV series called X or V or something, which was about aliens walking amongst us?

[00:35:28] [SPEAKER_03]: That's the other solution that they disguised as humans and they blend in with us.

[00:35:32] [SPEAKER_03]: So honestly, you can find Harvard academics or any academics anywhere.

[00:35:37] [SPEAKER_03]: Some academic will support some crazy theory.

[00:35:40] [SPEAKER_03]: And I think this one is particularly crazy.

[00:35:41] [SPEAKER_01]: And we've seen a lot of that from Harvard in recent months.

[00:35:44] [SPEAKER_03]: We've seen a lot of that from Harvard, yes.

[00:35:46] [SPEAKER_03]: So there's a lot of academics in Harvard, right?

[00:35:48] [SPEAKER_03]: So you're bound to have a variety of views, I think.

[00:35:50] [SPEAKER_03]: So if you can run the gamut from one to the other.

[00:35:52] [SPEAKER_01]: Not all views are of equal validity. That's the point.

[00:35:56] [SPEAKER_03]: That's the problem.

[00:35:57] [SPEAKER_03]: And so you mentioned it came from Harvard, which is a distinguished university.

[00:36:01] [SPEAKER_01]: It and Columbia are pretty much down the bottom of the barrel now,

[00:36:03] [SPEAKER_01]: but they used to be distinguished and reputable at one stage.

[00:36:06] [SPEAKER_03]: Yes, and old. Certainly no substantiation, no evidence, all hypothesis, all conjecture.

[00:36:11] [SPEAKER_03]: And stuff that's been done by science fiction writers for decades.

[00:36:15] [SPEAKER_03]: So nothing particularly new to see here, folks, except that it's coming from a university.

[00:36:18] [SPEAKER_01]: That's Tim Mindom from Australian Skeptics.

[00:36:21] [SPEAKER_01]: And that's the show for now.

[00:36:39] [SPEAKER_01]: Spacetime is available every Monday, Wednesday and Friday through Apple Podcasts iTunes,

[00:36:44] [SPEAKER_01]: Stitcher, Google Podcasts, Pocket Casts, Spotify, Acast, Amazon Music, Bytes.com,

[00:36:51] [SPEAKER_01]: SoundCloud, YouTube, your favourite podcast download provider,

[00:36:55] [SPEAKER_01]: and from Spacetime with Stuart Garry.com.

[00:36:58] [SPEAKER_01]: Spacetime is also broadcast through the National Science Foundation on Science Zone Radio

[00:37:03] [SPEAKER_01]: and on both iHeart Radio and TuneIn Radio.

[00:37:06] [SPEAKER_01]: And you can help to support our show by visiting the Spacetime store for a

[00:37:10] [SPEAKER_01]: range of promotional merchandising goodies.

[00:37:12] [SPEAKER_01]: Or by becoming a Spacetime Patron, which gives you access to triple episode commercial-free

[00:37:17] [SPEAKER_01]: versions of the show, as well as lots of bonus audio content which doesn't go to air,

[00:37:22] [SPEAKER_01]: access to our exclusive Facebook group and other rewards.

[00:37:26] [SPEAKER_01]: Just go to spacetimewithstuartgarry.com for full details.

[00:37:30] [SPEAKER_00]: You've been listening to Spacetime with Stuart Garry.

[00:37:34] [SPEAKER_00]: This has been another quality podcast production from Bytes.com.