InSight probe winding down activity

In other news, a sad moment is on the Martian horizon for the probe, InSight, its retirement looming. You can see from the lander’s own sad selfies that dust has accumulated over the solar panels, now only capable of generating a tenth of the power it did when it first touched down. For the rest of the summer, NASA will be using the remaining juice for just 12 hours a day, which will then drop down to 12 hours every other day before the power plus is metaphorically ripped out prior to the end of the calendar year. Dave Rothery from the Open University tells Harry Lewis what it’s all been for…

David - Insight is the NASA lander Mars that doesn't have a rover. It's just a static lander and it deployed, in particular, a sizmometer. It landed on the surface and, with its arm, it took its sizmometer out and placed it firmly into the ground and covered it with a lid to keep the wind off it. This sizmometer is sensitive to the vibrations in the ground caused by Mars-quakes. It's our way of listening to what's going on inside Mars.

Harry - And what has it been able to find?

David- Well, first of all, it's told us that Mars is seismically active. There are Mars-quakes. The biggest one, magnitude five on the famous Richter scale, happened only two or three weeks ago. We're able to use the wave vibrations that travel through the body of Mars, different types of vibrations, compressional waves and shaking waves, and look at the polarization of the waves as well. You can work out the layered structure of Mars, so we've detected that Mars does have a core for the first time. It's not a surprise, we expected it to have an iron core. It's a bit bigger than we expected, the crust of Mars is a little bit thinner than we expected - then there's a mantle in between. So, we've got the internal structure of Mars constrained and we think part of the core is probably fluid as well.

David - There's an experiment on board that measures the exact rotation of Mars, and how that varies on a fairly short time scale shows that Mars is a little bit sloppy inside. So, we've got hints of the core being fluid as well. If we're honest, we don't understand the early stages of planetary formation - when does for core separate from the rocky part and how thick the various layers are? What is going on inside a body? Why do we still have earthquakes on the earth? We know we 've got plates moving around as well as erosion and deposition changing the loading on the crust so things are creaking all the time. We don't have plates moving around on Mars, but we do have erosion and deposition, so the load on the crust is changing. But how does it respond to these changing forces? Insight has told us a lot about the inside of the planet and this hasn't been done before. The only body where a working size monitor has been deployed previously is onto the moon by Apollo astronauts who left four working sizmometers on the moon at the end of the Apollo program, but we've never had a sizmometer on any other planet. We've had one on Mars for three and a half years now.

Harry-  Other probes that are out there on Mars, I'm not sure how many there are, are they facing similar issues or is this something that is quite specific to Insight?

David- There are three rovers working on Mars at the moment, there's a Chinese one, which has been there several months now. We don't hear much of that. NASA has Curiosity, which I think has been going for a decade or more, and there's Perseverance, which landed early in 2021. That's just about to trundle up towards the top of the delta where it landed. So, we have rovers moving around Mars and because they're moving they don't get solar panels covered with dust and a lot of the power comes from radio thermal generators anyway, they've got plutonium on board to generate electricity from that process. They're not dependent on sunlight for power.

Harry- Where are we up to in Mars exploration? What are we expecting to happen in the near future?

David- Well, the big disappointment this year is for the Rosalind Franklin Rover, the European space agency lander on Mars, which now isn't going. This is because it was going to be launched on a Soyuz-Fregat launch vehicle from Kourou in French Guyana, and indeed the descent and landing system is Russian as well. The whole Ukraine situation means that that mission is not now going ahead. It would be great to have Europe's own Rover trundling around on Mars as well. I have a lot of colleagues who work very hard on defining the landing site and all their careers are on hold now. But, that aside, we are getting samples collected by NASA's Perseverance rover, which eventually will come back to earth through a joint NASA - European Space Agency project to bring samples of Mars back for analysis.

Harry- And that's a crazy thought that we'll soon have something that's so far away within reaching distance.

David- It'll be great to have samples from Mars that we've collected ourselves. We do have bits of Mars already because there are meteorites, chunks of rock that have been knocked out of Mars by impact, and then have gone through space and fallen down to earth and been recognized. So, we do have some out of context Mars samples, but we have nothing that we've collected ourselves.