this is bbc news. the headlines: search and rescue efforts are under way after one of the deadliest tornadoes to have ever hit the us state of mississippi. at least 25 people have died, with more thought to have been trapped under the rubble of destroyed buildings. the governor has declared a state of emergency. vladimir putin has said russia will station nuclear weapons in belarus — the first time it has deployed such arms outside its territory in almost 30 years. the us department of defence said it was monitoring the situation but did not currently see any reason to adjust its nuclear posture. the uk government is preparing to announce further alternatives to hotel accommodation for migrants as early as next week.

those behind the policy say it's a "big break" from hotels and a shift to more basic accomodation in an effort to deter people from coming to the uk illegally. now on bbc news, click. this week, get ready for blastoff — we are filming a hotfire rocket test in superslow—mo, and it will blow you away. woo! laughter. that went right through me! how do you choose your perfect shade? we've got an app to help

you build your foundations. and shona goes for a walk on the wild side, but you don't know what's around the next corner. we've discovered something like 20,000 new paths in the short time we have been running the project already. have you ever wondered what happens when a satellite goes wrong? how would you know what was up? how would you find out if it had been sabotaged? that's what i have come to texas to find out. 30 seconds... we are at this 200—acre site to film a hot fire test of a rocket engine. when it first starts up, it's going to be relatively gamey, you're going to see some shock waves. oh wow. and we are going to do it in a way that even the rocket makers themselves have not done before. four, three, two, one...

in 2022, firefly aerospace became one ofjust a few us companies that have successfully put things into orbit. look at that view! the company has also won contracts from nasa to build a lunar lander that will deliver payloads to the moon in 2024 and 2026, and put a satellite into lunar orbit. but it's the bit between launching from the earth and landing on the moon that has piqued my interest. we also want to build an orbiting spacecraft that has the ability to be on call for our customers. you can literally go to a web browser and say i have an asset in space and it is in distress, i'd like a camera shot of it, or it needs to de—orbit. firefly, can you do that? well, we can.

ultimately that will be a constalation of 30, 40, 50 of those spacecraft that are dispursed in the different regions of space and are on—call, available for customers say "to go over there. i have trouble." i need a pizza on the iss! we haven't really thought about the oven system of how we might keep the pizza warm... but we can do that! well i've seen the oven, it's strapped to the back. it's a little bigger. this is a pretty big deal. everything that is in orbit is going really really fast to make sure that as it falls towards the earth it continually misses it. changing course is not just a case of stopping and going in a different direction, because it will fall straight back to earth. no, this kind of manoeuvre needs maths and fuel, and lots of both. the early iterations that will have a finite set of fuel, but the next generations will be refuellable, or have soloar power, so they will be able to be recharged.

what is interesting is one of the reasons quoted for why you might need to go and check out another satellite is national security. in the example that bill gives me, imagine what would happen if a critical satellite mysteriously stopped responding to ground control. every satellite that deploys does not have a 360 camera or radar system, just for weight and space concerns. so sometimes they are blind objects up there that are just communicating their piece of data, so the ability to go to that region and say �*check that out for me�* is critical for national security. is there something attached to it? was it moved out of orbit? this constellation of rapid response satellites is planned to be in orbit by 2025, and before that, firefly is developing a rapid response rocket for the us space force that can be on standby and ready to take a payload and get it into orbit with just

one or two days notice. it takes four firefly designed reaver engines to get that rocket off the ground, and it is the test of one of those that we are here to film today. is this your baby or one of your babies? this is one of my babies. 0k. sporting her lucky launch shoes, bridget 0akes will be studying the rocket test in great detail. from an engine perspective, we want to make sure that our engines start up healthy, steady state that is healthy, and we are getting the thrust and power levels that we need, and a lot of that we can test on the ground because those are the things that we want to make sure are healthy in orbit. what is the height of it? is it pretty muchjust the horizontal frame? it does not go too high? now we brought along a friend to film the test. remember gav? he is one half of the slo—mo

guys who helped me get egg all over my face a couple of weeks ago, and he is going to be capturing the action at 2000 frames per second. that's 80 times slower than real life. the only thing is, he, like the rest of us, has to be hundreds of metres away when the rocket ignites. so i'm going to leave him to set the remote triggers and work out how his camera's not going to be incinerated, and we will come back later in the programme to see a rocket ignite like you have never seen before. nasa has been putting rockets into space since the �*50s and increasingly, it has been working with companies like firefly to deliver its stuff. mo has been finding out about its future plans with nasa's doctor kristinjohnson. and lift off of artemis i. the artemis moon mission signalled nasa's continued commitment to space exploration. what recent technological advances do you think make sustainable settlement on mars

a realistic proposition? oh, my goodness. we have had improvements in communication, a demonstration of the laser communications relay from the international space station, so laser communication is going to make the pipeline, you can get sent a whole lot more data. there's also been quite a bit of investment in al and virtual reality. people think gaming technology isjust for gaming but no, so imagine if we are going to have people living on mars, you are going to have to have a way to really to be able to assess what is happening inside the body without carrying an mri with you there. if you can imagine having sensors on your body or you can pull the heart out virtually and spin it around and see what is happening, that is going to be incredible. how important is the collaboration between nasa and private companies in achieving a sustained presence on mars? this is absolutely critical. there is no way that nasa can do this alone and there is no way that all the agencies,

the international agencies that nasa partners with, there is no way that they could do it alone. you think about spacex and the united states. spacex has gotten where it is in collaboration and partnership with nasa. nasa has invested quite a bit of money in spacex to help get where they are, and we are going to continue working with private industry companies like spacex and some of the new space companies that are coming out. does space have a role in helping us solve terrestrial issues? absolutely. the james west space telescope. in order for those mirrors to give you the beautiful images we have today, we have had to very precisely measure the curvature of those mirrors, so we came up with algorithms and technology to be able to do that, and we transferred that to the opthalmologist community so that they can scan

the surface of your eye very very precisely and quickly, so that they could determine astigmatism, farsightedness, nearsightedness on the international space station. we have a system that has to capture the waste water there, the water from your respiration, from your sweat and from your urine, and be able to take that and transfer it into drinking water, and apparently good tasting drinking water. they can actually take very contaminated water out of a field that is filled with bacteria and be able to process that water to get 99% of the bacteria and everything out of that so you can have pure drinking water in remote locations. when you have really impossible dreams, and impossible goals, if you reach for those goals and you create things that don't exist to achieve those goals, you inadvertently create incredible revolutionary changes for improving the quality of live right here on earth. time for a look at this

week's tech news. the tiktok boss testified before us congress to fight for the future of the social media app. this after president biden called for its sale to reduce potential influence by the chinese government. over half a dozen countries have full or potential bans of its use on government devices due to privacy and security fears. google has started rolling out its ai chatbot bard. the bbc was one of the first to try it out. let's start by asking bard to write a thank you note for a wedding gift. not bad. unlike chatgpt, it can access up—to—date information from the internet, but google warned that bard could have limitations and might share misinformation. amazon will cut another 9000 jobs as it seeks to save costs. with one and a half million people employed worldwide, cuts will fall in areas including cloud computing

and advertising. the firm had already said injanuary it was due to axe 18,000 jobs. microsoft has announced plans to launch its xbox mobile gaming online store next year. with an offering including call of duty and candy crush saga, it hopes to take on apple and google. one of the hottest trends in the cosmetics world is personalised beauty. brands are creating digital tools that recommend shoppers products like foundation or eyeshadow specifically for their unique skin type. there are plenty of personalisation services out there, but what about a device designed to detect the skin's undertone? skin undertone in cosmetics is basically what we call hue in science.

it's not about is your skin light or dark, nothing to do with lightness, it's to do with the colour that runs underneath your skin. so you can be very light and be pink, or you could be very light and be yellow and it's very important to know that so you can actually get beauty products that work for you. there are different ways to measure skin undertone, but the skin colour chart here which powers the tool makes the method unique. having an olive complexion, i really struggle to find make up that will match, and being a biochemist, i decided to look into it and i discovered that beauty magazines were recommending, look at your veins and that will help determine your undertones. we realised there was no way that actually skin was being classified accurately, so we thought we need to start right at the beginning, we started by reclassifying the entire human skin gamut and came up

with this index and that gave us the base to say now we understand the classification of human skin, we can digitalise the system. shall we give it a go? shall i give it a try? that's me taking my selfie, and can you tell me what does this information here say? it has identified five different types of undertone which is very different to what the beauty industry has at the moment. basically, it is saying that you have quite a large percentage of yellow and green in your skin which is the determining factor in our skins. the web—based tool is powered by a! which required a colour scientist from the university of leeds to analyse thousands of images of skin. some photos were captured in a very precise colour measurement camera booth, while others were snapped on phones, laptops or regular cameras,

but it was streamlining the quality of these images that proved challenging. when we use a smart phone to picture someone, it gets red, green and blue rgb values on every pixel. actually converting camera rgb values into something scientifically meaningful is very difficult. we used some relatively simple machine learning algorithms, but to do that we need to have lots of examples of images of people, and then their true skin colour, which we measure in the laboratory, and based on those two sets of data we can learn relationships between the two. what were your key findings in the process of creating the index? the main way in which people's skin colour varies is in terms of hue and lightness, but we actually analyse quite a lot of people who had very very dark skin in our process. we didn't find anybody with a blue undertone, if you like, so we tend to think that is probably a myth.

the web—based tool and the index provide a framework for detecting up to 10,000 different skin undertones. if you can basically specify every single person's skin colour uniquely, using their app and this index, then you actually have the potential in the future to match, for example, cosmetics foundation to an individual�*s skin colour. and in an industry where there is a lot of wastage, partly because people are buying the wrong products, further personalisation could be a good idea. we are hoping other people can come in, build on that knowledge to allow the beauty industry and other industries to really thrive, so that we can actually notjust talk about inclusivity in skin tone, but we can also make sure that consumers are being catered for properly.

scotland. there's no better place to enjoy nature. going for a walk and getting outdoors is so good for you — not just to stretch the legs but also for your mental health as well. but sometimes the route you want to go on just isn't on the map. well, it's hoped that's going to change and that's where these guys come in. this group are from ramblers scotland, a charity who are passionate about walking. scotland has really good access rights, so you can walk more or less wherever you wish, as long as you are responsible about it. but it lacks a complete map of its path network. so the charity has been creating a digital map of its own. it brings together all known

existing paths using data from ordinance survey and information from 0penstreetmap and local authorities. one of the surprising things about scotland as it is actually harder to find places to walk than you might imagine. we have got all this amazing green space around us but if you pick a paper map you might really struggle to find a path you want to walk. so one of the things we are trying to do with the scottish paths map is to actually make those places easier to find her everybody, wherever they live. how many paths do you think are out there for people to discover that aren't on the map? so we have discovered something like 20,000 new paths in the short time we have been running the project already. i think probably we could easily double the number of paths that people have to walk in scotland when they look at this map, compared to many traditional maps. we have hoovered up all the open source data, all the data we can get

from partners, but now we have 300—plus fabulous volunteers to discover more paths but also to record information about all the paths that we discover. the only way this was ever going to work is if we have the support of people who love the outdoors, who love walking, who love maps, who love technology. the tech is powered by ezrauk. the geographical software uses powerful mapping and spatial analytics technology. it allows the team to create and manage the location information, and it is all done on your phone. digital mapping is really the way forward, isn't it? yeah, it means we can make changes super quick and make it easily accessible to everyone, but also it is interactive and we can change things on the fly, we can highlight things, we can take things out, we can add things in, so it is much more responsive and adaptable compared to when you are updating stuff like paper maps. can you show me how it all works? of course. go to the map where you are, you find the path you want to audit, and you tap on the path and tap on open survey, and it takes you through to the questionnaire. and then we tell volunteers

they can fill in as much or as little as possible, a lot of the questions are not mandatory so if volunteers are unsure about something they can skip it, because we don't want to put them off, like, "i don't know the answer to that question so i won't do at all." volunteers have so far added over 9,000 new paths to the interactive map. from as far north as the shetland islands to the borders region in the south. i think the project is really important for our paths in scotland, it is a chance to support and to maintain that right to roam. but it also makes these paths more accessible to a wider variety of people, it means everyone can get out there. and we are on a nice path here in perthshire, is this a path you have been on before? it's not, and it is not one that is on the map yet. so today we are ticking another one off the list as we go. it's notjust the co—ordinates but the data about the routes and information the walkers might find useful that is recorded, like how steep

the hills are, is it muddy, is it stony, and even if there's angry landowners nearby. ramblers map shows the status of parts in different colours and volunteers use it to check what needs surveying. purple shows new paths yet to be audited, like the one we are standing on, and the green shows a completed path. just looking at the map you can see the majority of the 40,000 miles of paths still need to be audited — but if more volunteers come out and enjoy notjust the walks but the technology too, the team will only get closer to achieving their aim. now, earlier in the programme we'd met back up with gav from the slo mo guys to film a rocket engine test at 80x slow motion — that's 2000 frames per second. and here's how we got on. we are in a nice, flat part of texas. seems like a sensible place to do a rocket

test, doesn't it? and as you walk along you start to get hints that yeah, there is something going on here. lots of compressed nitrogen in canisters. when you get to this shed, there is a massive canister of something there. some more serious and complicated looking pipes, some dials. you start to get the impression yeah, the engine must be quite close by now, and then — oh, actually, this is actually the engine that we have been walking past. they have attached it to a building, so at least it's not going to go anywhere. and what is interesting is how we have to film this test. we have to put our cameras inside these protect their boxes, for obvious reasons. and then a whole hour before they run the test, we need to clear out of here, which means we have to run a really long remote control wire for our cameras all the way around to that remote viewing area there. we did bring the really long wire, didn't we? the camera is locked down and the remote control line is set.

and with duckner left in charge of the heat absorption lake and us having retreated to a safe distance... 0perator, please start the hot fire router. ..it is time. in three, two, one. engine roars you can feel the rumbling! woo! laughs. that went right through me. wow! that was so loud and so bright, my eyes couldn't — that's like looking at the sun. wow!

and finally, it's time to see whether we caught the shot that everyone wants to see. what were the risks? the power could have come out, the trigger could have been wrong, the camera could have melted, an asteroid could have come straight down. 0k, well, ithink that didn't happen. all right. so we seem to have... 0h! 0k. immediately! that's footage. oh, wow. it's just igniting the air. look at the shock waves on the flame. oh my gosh, this is kind of pulsing. that is incredible. that is so cool. so that smoke is coming out at quite a speed. look how dark i made this image, and it is still very bright.

but we are seeing detail, we are seeing information right around the end of the booster there. and that is it for this week — i will leave you with the beauty shots. oh, and if you are worried about duckner, he was found 500 feet away and returned to his natural habitat, uncooked. hello. looks like things are turning colder brieflyjust—in—time for british summertime. 0ur clocks went forward one hour during the early

hours of sunday. it will be turning colder across northern areas today and we will start to notice the difference in the south once we lose the early morning rain, all courtesy to this area of low pressure, pushing into the near continent as it pulls away, northerly winds will set and initially across the north of the uk and then spread outwards and you notice the blue colours spreading to pretty much all areas by the end of sunday. but we start this morning on a rather wet note across southern areas, that rain takes its time to clear away from east anglia and the south—east, could leave a bit of a hang back of cloud for the north. some good spells of sunshine around but it will be cold in the northerly wind with some showers which will have a wintry element to them particularly in north and east of scotland so temperatures here, low single digits and single figures for much of england and wales as well, away from the southwest. as we move through sunday night, that cold air spreads southwards, sky is clear, it is going to be a very cold night, widespread frost i think away from the far south—west of england and south wales,

so ice and frost could be an issue. into monday, we are in between weather systems, this will arrive as we head into tuesday but a ridge of high pressure will bring a lot of fine and dry conditions on monday to much of the uk, it will start cold and frosty mind you, watch out for any early ice across northern areas and it should stay sunny into the afternoon as well. cloud tending to build a southern and western areas later on, temperatures lifting to 11 degrees but after that cold start in the strong late march sunshine, temperatures will reach highs of 7—9 celsius. on tuesday it starts to turn cloudier, windier, wetter, rain pushes in, preceded by some snow certainly across the hills and across the north of england and scotland but temperatures will be on the rise you will notice, southern and western areas, we are back into the low teens and beyond tuesday, it looks like low pressure dominates the scene, sitting out to the west of us ushering in some very mild airfrom the south—west there will be strong winds and rain too. i think one of the mildest days will be thursday, we could be up to 16 or 17 degrees across southern and eastern areas but it will be mild and unsettled

right across the board.

this is bbc world news. i'm monika plaha. our top stories: a state of emergency in mississippi after a violent tornado kills at least 25 people. as soon as we would go from one vehicle to the next vehicle orfrom building to building, we could hear screams and we could hear cries for help. donald trump heads to texas to start his campaign to win back the us presidency in 2024. vladimir putin says russia has agreed to keep tactical nuclear weapons in neighbouring belarus. thousands of israelis take to the streets for the 12th straight week protesting benjamin netanyahu's proposed changes to the law.