Curiosity’s Spare Rover Heads to the Moon: Gravity Reconnection, Record-Cold Atoms...

[00:00:00] [SPEAKER_01] Somewhere in a building at the Jet Propulsion Laboratory sits a Mars rover that never went to Mars. It's Curiosity's twin, the testbed vehicle that rehearsed every drive before the real one made it on the Red Planet.

[00:00:14] [SPEAKER_02] And on Saturday, NASA announced it's finally getting a mission. Not to Mars, though. To the Moon's south pole, with a nuclear generator, a drill, and a job scouting the ground for the first lunar base.

[00:00:26] [SPEAKER_01] Also today, a new way of reading Einstein's equations that lets gravity behave a bit like a solar flare. A record-breaking cold experiment on China's space station. And the second of NASA's twin Mars probes firing its engine right over southern Australia.

[00:00:43] [SPEAKER_02] And I'm Avery. Let's get going.

[00:00:45] [SPEAKER_01] Hitting the start button now.

[00:00:47] [SPEAKER_02] On Saturday, at an aerospace expo and air show at Kennedy Space Center, NASA announced a whole bundle of Moonbase awards. The one that's going to stick in people's minds is a rover called PROMISE. That stands for Polar Rover for Observation, Mapping, and In-Situ Exploration.

[00:01:04] [SPEAKER_01] And it's nuclear-powered, which is the headline.

[00:01:07] [SPEAKER_02] It is. But the bit I find most interesting is where it comes from. JPL isn't building a new rover from scratch. Engineers are taking the electronics, body structure, and mobility system from the duplicate version of Curiosity. The one that served as the vehicle system testbed for the Mars mission. And turning it into a lunar rover. They'll add flight spare and testbed parts built for curiosity and perseverance.

[00:01:33] [SPEAKER_01] So the rover that spent years driving the Mars yard so that the real curiosity didn't have to take risks, finally gets to go somewhere.

[00:01:43] [SPEAKER_02] That's the story. And it's powered the same way, by a flight spare multi-mission radioisotope thermoelectric generator, an MMRTG. That's essentially a nuclear battery. The heat from decaying plutonium is turned into electricity. Same kind of power source that's running Perseverance right now.

[00:02:02] [SPEAKER_01] Let's get to why that matters on the Moon specifically. Because solar panels work fine on the Moon most of the time.

[00:02:09] [SPEAKER_02] Most of the time is the catch. A lunar night lasts about two Earth weeks. Solar-powered landers either shut down or freeze. And promise is going to the South Pole, where there are craters whose floors haven't seen sunlight in billions of years. NASA calls them permanently shadowed regions. Some of them are among the coldest places measured in the solar system.

[00:02:33] [SPEAKER_01] And those are exactly the places where the water ice is supposed to be.

[00:02:36] [SPEAKER_02] Exactly. Ice that could be drinking water, breathing oxygen, rocket propellant. That's why everyone wants to land near the South Pole.

[00:02:44] [SPEAKER_01] How sure are we that it's there?

[00:02:46] [SPEAKER_02] Sure enough to plan around. Not sure enough to build on. The best direct evidence is from 2009, when NASA deliberately crashed a spent rocket stage into Cabeas Crater near the South Pole. The LCROSS mission. And a trailing spacecraft saw water in the plume of debris. Since then, orbiters have mapped hydrogen, cold traps, and ice signatures in the shadows.

[00:03:12] [SPEAKER_02] But all of that is from a distance. Or from a single violent splash. Nobody has driven into one of those dark craters and dug. And a solar rover can't do that. It can't. NASA's own numbers for the shadowed craters run as low as minus 242 degrees Celsius. To give our sense of scale, Jackleton Crater, right next to the pole, is about 21 kilometers wide and 4 kilometers deep, with a floor in permanent shadow.

[00:03:43] [SPEAKER_02] A nuclear rover can keep its electronics warm, keep its batteries topped up, and keep working in the dark, where a solar rover would simply stop.

[00:03:51] [SPEAKER_01] So what's in the toolkit?

[00:03:53] [SPEAKER_02] The centerpiece is a drill called Trident, built by Honey Bee Robotics. It brings regolith up from as deep as a meter, in 10-centimeter steps, and measures how hard and how cold the ground is as it goes. Then there's a mass spectrometer, called mSolo, to sniff the gases released from that material. A near-infrared spectrometer, called Nervis, to look for ices and minerals. And a neutron spectrometer that detects hydrogen under the surface. Those four sound familiar.

[00:04:22] [SPEAKER_02] They should. They're the same four instruments flying on Viper, the earlier ice-prospecting rover. NASA's framing is that the two rovers will give complementary datasets from two different parts of the South Pole, which is a sensible way to turn one measurement into a comparison. What else? A radiometer called La Forge, to map how cold the shadowed regions get. Built on sensor technology from the Diviner instrument on the Lunar Reconnaissance Orbiter.

[00:04:51] [SPEAKER_02] A radiation detector, Rad, whose earlier version has been running on Curiosity on Mars for 15 years. A laser reflector, so orbiting spacecraft can pin down where the rover is to within centimeters. And a camera suite NASA's calling the Lunar Dash Cam, built from the system that filmed Perseverance landing.

[00:05:11] [SPEAKER_01] And there's a self-driving angle too.

[00:05:13] [SPEAKER_02] There is. A new radiation-tolerant computer. A lidar to map the terrain in 3D. And autonomy software meant to let the rover drive further in the dark, with less hand-holding from Earth. Even the wheels are an instrument. NASA says the rover might use one of them to dig a trench and record how the ground behaves. How firm or loose the regolith is, matters a lot when you're choosing where to land something heavy. When does it fly?

[00:05:41] [SPEAKER_02] NASA is targeting late 2028, with an 18-month primary mission. Blue Origin has been awarded a $94 million base contract, with an option worth up to another $140 million depending on performance, to deliver it on its Mark I lander.

[00:05:57] [SPEAKER_01] And promise was only one piece of Saturday's announcement.

[00:06:00] [SPEAKER_02] Right. NASA picked eight companies for the next phase of its commercial lunar delivery program, CLPS-2. Blue Origin, Firefly, Intuitive Machines, iSpace US, Lockheed Martin, Northrop Grumman, SpaceX, and Voyager Technologies. It's a 10-year contract with a combined maximum value of $10 billion. The original CLPS contract was raised from $2.6 billion to $4.2 billion.

[00:06:28] [SPEAKER_01] Then there's a separate set of launch and transport orders.

[00:06:31] [SPEAKER_02] Six task orders, worth about $1.3 billion combined, to Aeroscience and Technology, Blue Origin, and Impulse Space. They include flying Capstone O2 to test navigation and communications around the moon, and delivering Moonfall, a set of drones designed to scout the South Pole before astronauts arrive. And SpaceX will fly communications satellites on a starship to cislunar space in 2028.

[00:06:56] [SPEAKER_01] Let's be careful with those big numbers.

[00:06:59] [SPEAKER_02] Yes. $10 billion is a ceiling, not money spent. That kind of contract sets the maximum that can be ordered over 10 years. And the companies still have to compete for individual missions. And late 2028 is a target. Lunar landers have had a rough record of slipping, and of landing badly when they do get there.

[00:07:18] [SPEAKER_01] And there's no Australian angle hiding in this one.

[00:07:20] [SPEAKER_02] No. And I won't invent one. This is an American program with American contractors. What I'd point to is what it means for the science. For decades, lunar ice has been a line on a map, made from orbit. Promise is designed to put a drill into the ground where the map says the ice should be, and tell us whether it's there, how deep, and how much. If the answer is less than hoped, that's just as important to know before anyone builds anything.

[00:07:48] [SPEAKER_01] A spare rover, a spare power source, and a very real question. I like it.

[00:07:55] [SPEAKER_02] Now for something completely different. A theory paper. Luca Comiso at Columbia University and Felipe Asenio at Universidad Adolfo Ibañez in Chile have published a study in Physical Review D called Reconnection of Gravitational Fields. It appeared on the 28th of October, and a preprint has been around since September.

[00:08:17] [SPEAKER_01] And the idea borrows from the sun.

[00:08:19] [SPEAKER_02] It does. In a plasma, magnetic field lines get stretched then twisted until, in the right conditions, they snap and reconnect in a new arrangement. That's magnetic reconnection. It dumps the stored magnetic energy into the particles, and it's the engine behind solar flares. Camiso has worked on reconnection for years.

[00:08:40] [SPEAKER_01] So the question is whether gravity can do something like that?

[00:08:44] [SPEAKER_02] Right. Einstein's equations can be rewritten using quantities that behave a lot like electric and magnetic fields. Because phase time has four dimensions rather than three, the gravitational equivalent of a field line is a sheet. Camiso's comparison is that if you put lots of lines together, you get a sheet. Under ideal conditions, those sheets keep their connections. The new paper works out what happens when those ideal conditions break down. The sheets can reconnect.

[00:09:14] [SPEAKER_02] And when they do, energy moves out of the gravitational field and into matter.

[00:09:18] [SPEAKER_01] And they can put numbers on it?

[00:09:19] [SPEAKER_02] They derive measures of how fast it happens, and show it changes how energy and momentum are exchanged between gravity and matter. Asenjo's point is that Einstein's equations contain constraints on how space time can evolve that aren't obvious until you write them this way. Now the caveats. Two of them. First, these sheets are mathematical tools, not physical surfaces. Space time isn't tearing like fabric.

[00:09:48] [SPEAKER_02] Second, this is purely theoretical. Nobody has observed gravitational reconnection. The obvious place to look is in black hole and neutron star mergers, where gravitational fields change violently and quickly. So the open question is whether it leaves a signature in the gravitational waves we already detect.

[00:10:06] [SPEAKER_01] So it's a new lens on equations we've had for 110 years.

[00:10:11] [SPEAKER_02] Exactly. A lens. Not a discovery. Yet.

[00:10:15] [SPEAKER_01] From the hottest energy releases to the coldest matter. A team working with China's Tiangong space station reported in Science last week that they cooled a cloud of atoms to an equivalent temperature of 9.7 pico-Kelvin.

[00:10:31] [SPEAKER_02] Pico-Kelvin being trillionths of a degree.

[00:10:35] [SPEAKER_01] Trillionths of a degree above absolute zero. The atoms are rubidium-87, about 20,000 of them. And at those temperatures, they merge into a single quantum state, called a Bose-Einstein condensate. Instead of a crowd of individual atoms, they behave as one giant matter wave. Why go to space for this? Gravity. On the ground, the cloud falls. So you have to hold it in a trap.

[00:11:01] [SPEAKER_01] And the trap itself limits how weakly you can confine it and how long you can watch it. In orbit, everything's in free fall, together. The cloud can drift and expand for a long time. The Chinese Academy of Sciences says they observed it for seven seconds after release. It doesn't sound long, but for a cold atom experience, it's huge. And expansion is how they got it so cold? Right.

[00:11:25] [SPEAKER_01] They combined evaporative cooling, where the most energetic atoms are allowed to escape, with a further stage in which the cloud is allowed to expand, which lowers its energy even more. One honest note that 9.7 pico-Kelvin is an equivalent temperature, a way of expressing how little kinetic energy the atoms have left, not a thermometer reading in the usual sense.

[00:11:44] [SPEAKER_02] How does it compare with the record before?

[00:11:47] [SPEAKER_01] NASA's Cold Atom Lab on the International Space Station reported Bose-Einstein condensates expanding with energies of a few tens of pico-Kelvin in 2022. So this goes a step colder. The hardware is a cold atom physics rack built by Peking University and the Shanghai Institute of Optics and Fine Mechanics, carried up on the Mengtian module in October 2022.

[00:12:12] [SPEAKER_02] And the payoff?

[00:12:13] [SPEAKER_01] Mostly precision. Ultra-cold atoms make extraordinarily sensitive sensors. Atom interferometers that could measure gravity, test whether everything really falls at the same rate, or one day help search for dark matter. The Chinese team has also invited researchers worldwide to propose experiments on the facility.

[00:12:34] [SPEAKER_02] A follow-up to our story from episode 222. NASA's twin Escapade spacecraft, Blue and Gold, spent the past year looping around the point a million and a half kilometers beyond Earth, waiting for Earth and Mars to line up. This month, each one has to fly back past Earth and fire its engine at closest approach to slingshot itself to Mars.

[00:12:54] [SPEAKER_01] It's a maneuver no NASA spacecraft has flown before. A powered flyby. Right.

[00:13:01] [SPEAKER_02] The trick is called the Oberth effect. A rocket burn is most efficient when you're already moving fastest, which is when you're closest to Earth. Each burn lasts about nine minutes and adds more than 1,600 kilometers an hour, taking each spacecraft from about 10.1 to 10.8 kilometers per second. And Blue went first on Saturday. Blue's burn began at 8.51 p.m. Australian Eastern Daylight Time on Saturday the 7th over Southern Australia.

[00:13:30] [SPEAKER_02] Gold's began at 9.51 p.m. Monday night Sydney time, which was 5.51 a.m. Eastern in the U.S., again over Southern Australia.

[00:13:39] [SPEAKER_01] And Gold's burn is confirmed as well?

[00:13:42] [SPEAKER_02] Yes, NASA has confirmed both burns went ahead. Both twins are now on their way to Mars.

[00:13:47] [SPEAKER_01] And the team won't know exactly how well they're aimed for several days. That's right.

[00:13:53] [SPEAKER_02] Small correction burns will tidy up the path over the 10-month cruise, with arrival at Mars planned for the 7th and 9th of September, 2027. Then they'll fly in formation and measure how the solar wind is stripping away the Martian atmosphere. And if the strategy works, it means Mars missions don't have to launch in that narrow window every 26 months.

[00:14:14] [SPEAKER_01] A few quick ones. Starship Flight 15 is targeted for Friday the 13th of November, with the window opening at 4.45 p.m. Central Time. That's 22.45 UTC or 9.45 on Saturday morning in Sydney. It's pending regulatory approval, and SpaceX says it's aiming to catch both the super heavy booster and the Starship upper stage with the tower for the first time.

[00:14:37] [SPEAKER_02] Targeted, not scheduled. We've learned that lesson.

[00:14:39] [SPEAKER_01] We have next, Voyager 1 is about to become the first spacecraft to sit a full light day from Earth. Meaning its signals take 24 hours to reach us. As I expect the milestone around the 18th of November, and is marking it on the 17th with an event called Shine Bright for Voyager's Light Day.

[00:14:59] [SPEAKER_02] 49 years to get there.

[00:15:01] [SPEAKER_01] And finally, ESA says the first stage of Euclid's data release one is due this month. Raw data, calibrated images, catalogs, and spectra covering about 1,900 square degrees of sky. No exact date yet, but we'll be watching.

[00:15:16] [SPEAKER_02] Time to look up! The moon was new on Monday at 6.02 p.m. in Sydney, 2.02 a.m. Eastern in North America. So this week starts with dark skies everywhere.

[00:15:26] [SPEAKER_01] The best show is in the morning. Venus is low in the east before sunrise, sitting about a degree from Spica, the brightest star in Virgo, on Monday and Tuesday mornings. Venus is far brighter, magnitude minus 4.2. So look for Spica as a fainter point beside it.

[00:15:45] [SPEAKER_02] And this is one where the North does better. At civil dawn, Venus is about 17 or 18 degrees up from Los Angeles and New York, 13 from London, but only about 11 from Sydney. You'll want a clear eastern horizon here in the south. Then there's Mars and Jupiter. They're still closing in. On Tuesday, they're about 2.5 degrees apart. And on the 16th, they reach about 1.2 degrees by our own calculation.

[00:16:13] [SPEAKER_02] Some listings give less than a degree, so expect a slight disagreement between sources. Jupiter's the bright one, around magnitude minus 2. Mars is the fainter orange one. They're near Regulus and Leo.

[00:16:26] [SPEAKER_01] And again, the North gets the higher view.

[00:16:28] [SPEAKER_02] Much higher. At civil dawn on Wednesday, they're 65 to 70 degrees up from Los Angeles and New York, over 50 from London, and 33 or 34 from Sydney. Still very easy from the south, just lower in the northeastern sky.

[00:16:45] [SPEAKER_01] The evening belongs to the south. The thin crescent moon comes back into the western sky. And on Wednesday evening, the 11th, it sits about 2 degrees from Antares, the red heart of Scorpius, around 8 o'clock in Sydney.

[00:16:58] [SPEAKER_02] And from London, the moon has already set by then. While from New York, it's barely 5 degrees up, half an hour after sunset. From Sydney, it's 16 degrees up and climbing higher each night. By Friday, it's over 35 degrees up at dusk.

[00:17:13] [SPEAKER_01] Saturn's up in the evening, too.

[00:17:15] [SPEAKER_02] It is! Half an hour after sunset, Saturn's about 45 degrees up from Sydney, against 24 to 30 from New York and Los Angeles, and about 16 from London. It's a good week for a telescope while the moon is still thin.

[00:17:27] [SPEAKER_01] The northern torids peak around the 11th and 12th. It's a slow, modest shower, maybe a handful an hour, but it's known for bright fireballs. At midnight, the radiant in Taurus is about 30 degrees up from Sydney, and 60 to nearly 80 degrees up across the northern cities. So the north will see more.

[00:17:46] [SPEAKER_02] And looking ahead, the Leonids peak on the 17th. At 4 in the morning, their radiant is about 50 to 60 degrees up from the northern cities, but only around 16 degrees from Sydney. First quarter moon sets around midnight, so the pre-dawn hours will be dark.

[00:18:01] [SPEAKER_01] And for southern observers with a dark sky this week, there's the 4 galaxy talent. Yes.

[00:18:07] [SPEAKER_02] With no moon in the evening sky, you can try to see the large and small Magellanic clouds, the Milky Way, and the Andromeda galaxy. With your eyes in one session. That's a southern special. From the north, the Magellanic clouds never rise.

[00:18:22] [SPEAKER_01] And our standing reminder. Never look at the sun directly, through binoculars or through a telescope without proper protection. If you're observing the sun, use only eclipse glasses or solar filters certified to the ISO 12312-2 standard. And check them for damage before every use.

[00:18:42] [SPEAKER_02] That's the show. A curiosity spare heading for the moon's south pole, gravity behaving like a solar flare on paper, atoms colder than anything ever recorded, and two small spacecraft on the way to Mars.

[00:18:57] [SPEAKER_01] If you've got a question about anything in today's episode, send it through the contact form at AstronomyDaily.io. Some of our best segments have started with listener questions.

[00:19:07] [SPEAKER_02] You'll find the show notes, links, and our newsletter there too. And we're at AstroDailyPod on social media.

[00:19:15] [SPEAKER_01] Astronomy Daily is part of the Bytes.com podcast network. I'm Anna.

[00:19:20] [SPEAKER_02] And I'm Avery. Clear skies everyone. And we'll see you tomorrow.