Naked Science Questions and Answers

26 March 2006


Answering all your burning science, technology and medicine questions this week are Drs Chris, Dave and Phil, who will be looking at why purifying seawater is not the answer to water shortages, how 3D glasses work and whether a man on a meteor would have to hold on tight or just soak up the stellar scenery. Also on the show, Daniel Scuka at the European Space Agency provides a Venus Express update, Diana Liverman talks about how to turn down the heat on climate change, and in Kitchen Science Anna Lacey finds out why we hear strange voices when we play old records backwards.

In this episode

A Whiff of Methane Has Helped Japanese Researchers To Sniff Out Signs of Earth's Earliest Life in Rock Samples From Western Australia. Yuichiro Ueno And his Colleagues At The Tokyo Institute of Technology Studied Samples of

Flexible Flight

Researchers at MIT have found a way to take the drag out of flying, at least for the wings if not the passengers. Aeroplanes are currently controlled by wing flaps that hinge up and down, which change the shape of the wings and alter the flow of air over the surface. The major disadvantage of wing flaps is the creation of a corner which leads to the formation of drag, reduced speed and decreased manoeuvrability. The problem could be solved by using a material that changes shape smoothly, allowing the wing to bend without drag. But until now it seemed that such a material had evaporated into thin air. However, scientists at MIT may have discovered a solution. They noticed that the compounds used to store energy in lithium rechargeable batteries change shape as they charge and discharge, which occurs due to the movement of ions in and out of the material. The researchers took advantage of this gentle bending and incorporated the material into the wings. In addition to changing shape, the material is light and can even morph under large forces. This means that the pilot can still control the plane even when heading towards the ground at high speed. Although a breath of fresh air for aerodynamics research, practical applications for the material are still in the development stages. However, the high flying scientists hope to have made a shape-morphing helicopter blade by the end of the year.

Decoding a computer-generated voice

Anna - Welcome to the King's School in Ely where this week we're going to be astounding you with sound and finding out all the glorious glorious things about the science behind music. And here to help us do that this week, we've got our amazing science guru Wendy. So , can you introduce yourself?

Wendy - I'm Wendy Sadler and I'm from Science Made Simple and we take loads of science stuff around to schools and try and make it fun and really exciting.

Anna - What is it that we're exactly going to be doing today?

Wendy - Today we're going to be testing out people's listening skills and we're going to see how good they are at spotting some words within an electronic voice.

Anna - Wow that sounds pretty intriguing. Also here with us, we've got some student helpers. So can you tell us your name and your ages please?

Emily - Hi I'm Emily and I'm ten years old.

Anna - And what about you sir?

Matt - I'm Matthew and I'm nine years old.

Anna - And so Matt, what's your favourite thing about science?

Matt - It's probably the experiments.

Anna - And obviously most importantly, do you know anything about the science behind music Emily?

Emily - No!

Anna - That is a good job because that's exactly what we're here to tell you today. So what exactly is it we're going to be doing Wendy?

Wendy - We're going to be doing a fun experiment that's about the science of sound and also bout how our brains work. We're going to play a clip in a moment which is a very early attempt at a computer trying to speak. So it's a computer synthesising a human voice. The human voice is a very complicated sound. It's quite hard to work out what it's saying, so this is the challenge for everyone, to listen and see if they can work out what the voice is saying.

Anna - So people at home, you should be listening very carefully to what Wendy's going to play you here. You need absolutely no equipment whatsoever so there are no excuses this week. So Wendy's going to play this song for us now and I want you guys, Matt and Emily, to try and tell us what you think it says…. Any ideas?

Emily - No!

Anna - And what about you Matt?

Matt - I haven't got a clue.

Anna - Can we hear it again Wendy, and this time we'll listen a bit more carefully…. Were there even any words that you could pick out there Emily?

Emily - Absolutely none.

Matt - I think I heard sound at one point.

Anna - Ok so we've got a bit of a hypothesis there. Well we're not going to tell you exactly what it says quite yet because we want you people at home to have a think about what it said. We'll be playing it again later on in the show and we want you to phone in and tell us what you think they said. Thanks to Wendy, Matt and Emily and we'll be going straight back to the studio now.

LATER ....

Chris - Anna, let the cat out of the bag. What does it say?

Anna - Hello and welcome back to the King's School in Ely where we're here with Wendy from Science Made Simple and our student helpers Matt and Emily. Now what we've been doing is listening to some very strange computer generated voices and having no idea whatsoever about what it's saying. So what are we going to do now then Wendy?

Wendy - Well before we reveal the answers, we'll play it one last time to give people their last chance to see if they can get any words. I think Matt picked one up before.

Anna - Ok well that's still all Greek to me, so Matt can you reveal exactly what it says here?

Matt - Sound and music can be used for the synthesis of speech.

Wendy - It sounded a bit different when Matt said it!

Anna - It did indeed sound different. So can we actually see whether it actually said sound and music can be used for the synthesis of speech?

Wendy - Ok, this is exactly the same track again and I haven't changed it at all.

Anna - Emily, could you hear that this time?

Emily - Yes.

Anna - Are you sure?

Emily - Well I can hear bits of it now that I know what it's saying.

Anna - Shall we listen to it one more time? Sound and music can be used for the synthesis of speech.

Wendy - Matt actually picked up one of the words because he got sound right.

Anna - Wow that's absolutely amazing. I really can hear that. How did you make that sound in the first place using a computer voice? How does that all work?

Wendy - Well this is quite an early attempt at computer voice synthesis, but it's actually quite hard to copy a human voice. Every time you speak, you've got two elements of sounds going on. One is the pitch part, so you're essentially singing as you speak. You can speak really high or you can speak really low. That's one part the computer has to generate. The second thing it has to do is generate these sounds that are like percussion. They're called fricatives which are things like 'p' and 'k' and they're very hard sounds to form. Now one of the problems with this voice is that when you hear it you'll hear it's all on one pitch. This makes it sound very robotic. You immediately know that it's not human being and it's very hard to copy a human voice. It's almost as unique as your fingerprint. The reason it's very hard to understand is that you've only got one pitch and it's not very good at making those 'p' and 'k' sort of sounds.

Anna - But why is it that as soon as you showed us exactly what it was and showed us those words sound and music can be used for the synthesis of speech, that then all of a sudden we could hear it?

Wendy - Well your brain is really powerful at filling in the gaps and obviously if you suggest to someone what they're meant to be hearing then when they hear the words in their head and hear the voice again, they can put in all the stuff that was missing.

Anna - So is that kind of like when I'm listening to someone in French and I only know a few French words, I can fill in the gaps and kind of get what they're saying?

Wendy - Yes. You can put the sentence together effectively by the words that you're missing. In fact it's a little bit like when people suggest that they can hear hidden lyrics in songs played backwards. If someone suggests to you that you can hear these certain words, then you're likely to hear them because you are expecting them.

Anna - And Matt, you had a question.

Matt - It seemed really amazing that when we knew what it was saying, that it seemed so much clearer.

Anna - Yeah that really was amazing and now do you feel that you understand exactly why that was, with our brains filling in the gaps?

Matt - Yeah.

Anna - And what did you think of the experiment then Emily?

Emily - Quite weird!

Anna - And were you expecting it to actually say anything in the end?

Emily - No.

Anna - Well I have to say thanks very much Wendy for that. Computer voices and our brains being amazing and filling in the gaps. Well that's it for this week and that's enough from the King's School in Ely. Thanks very much Emily, Matt and Wendy. Did you enjoy yourself Wendy?

Wendy - Yeah it was great fun.

Anna - Thanks very much. We'll be back doing some more kitchen science next week somewhere in the Eastern region. So goodbye for now.

- Tracking Venus Express

The Naked Scientists spoke to Daniel Scuka from the European Space Agency

Tracking Venus Express
with Daniel Scuka from the European Space Agency

Chris - There's mission called Venus Express which is going to meet our near planetary neighbour, Venus. Already in the series, we've heard how Venus has a runaway greenhouse effect and also we want to find out if there are active volcanoes on the surface. Well this week, in part three, we're going to be catching up with Kris Capelle about ESA's worldwide network of ground tracking systems. Here's Daniel Scuka, who brings this report from ESA.

Daniel - Venus Express is a fantastically advanced spacecraft and in April it will enter into orbit around Venus with seven sensitive instruments to gather a wealth of data. But that data has to be transmitted to Earth and throughout the mission, telecommands and instructions must be radioed up from the ground. This is where the European Space Agency's worldwide ESA Tracking Ground Station Network comes into action. ESA maintains eight stations in the ESTRACK network, located in Spain, Belgium, Sweden, South America and Australia. Earlier this week Kris Capelle, Venus Express operations manager, was in the main control room at ESOC, participating in an intensive simulation exercise.

Kris - The stations are controlled locally from ESOC so we do remote control of the stations, except for critical operations like the Venus orbit insertion.

Daniel - The ESTRACK system comprises six stations having smaller 15 metre antennae and two deep space stations with giant 35 metre antennae. These latter two are located in New Norcia, Australia and Cebreros, Spain. Venus Express is being telecommanded via the 35 metre station in Cebreros, which is the newest station to join ESTRACK. Having been completed in September 2005 on the site of an old NASA Apollo tracking station. The Cebreros ground station communicates with Venus Express at X-band gigahertz radio frequencies.

Kris - For Venus Express we're using eight gigahertz. It's about eighty times more than a normal radio station

Daniel - But die to the Earth's rotation, the station can only send telecommands or receive data when Venus Express passes overhead. As a result, the spacecraft gathers data in a store and dump mode; storing precious science data on board in a twelve gigabit memory array until it can contact Cebreros for download. During the upcoming and risky Venus Express orbit insertion, the spacecraft will be 125 kilometres from Earth and it will take radio signals travelling from Cebreros at the speed of light, six minutes and 46 seconds to reach the spacecraft. I asked Kris how many missions ESA is currently controlling from ESOC.

Kris - We have 14 satellites flying. We have scientific satellites like XMM, and we have our Earth observation satellites, and then we have our deep space satellites like Venus Express, Mars Express and Rosetta, and Smart 1 around the Moon.

Daniel - During next month's orbit insertion, the X-band antenna on the spacecraft will not be facing Earth. Only the smaller and weaker S-band antenna will. So ESA has asked NASA to help out.

Kris - They have 70 metre dishes and for some deep space missions we are requesting their support just to get some additional coverage or communication with the satellite.

Daniel - Join us again next week for a report direct form ESOC's main control room when we speak with the veteran ESA flight director on the high tech drama that takes place here during launches, orbital manoeuvres and landings. For the European Space Agency, I'm Daniel Scuka reporting from the European Space Operations Centre in Darmstadt, Germany.

- Science Update - Communication and Cat Proteins

The Naked Scientists spoke to Chelsea Wald and Bob Hirshon

Science Update - Communication and Cat Proteins
with Chelsea Wald and Bob Hirshon

Chris - Every week we cross the pond to find out what's going on courtesy of the American Association for the Advancement of Science. Chelsea Wald and Bob Hirshon are there with Science Update, and this week they're going to be telling us about how disabled kids could be better at communicating, how cats could be knocking off sea otters and also getting proteins out of prehistoric things like dinosaurs.

Chelsea - For the Naked Scientists this week we'll be taking a look at new technologies that are helping disabled children find their voices. But before that we have a story of particular interest to cat lovers. New research shows that keeping cats indoors instead of out is not only safer for them but is also safer for other cute fuzzy animals too.

Bob - That's right. Cats are killing sea otters in California, but probably not in the way you're thinking. Cats carry a parasite called toxoplasma that they shed in their faeces. That's according to scientist Pat Conrad of the University of California at Davis.

Pat - When cats defecate outside or if cat litter is dumped outside and then it rains, those parasites are washed into rivers and streams and those ultimately reach the ocean.

Bob - There the parasite causes brain disease in sea otters, killing many of them outright and making others easier prey for sharks. Conrad says that sea otters are vulnerable because they live near the coast, but other marine mammals such as manatees can also get infected, In humans, toxoplasma can be dangerous for pregnant women or people with weak immune systems. Conrad says pet owners can control this parasite by keeping their pets indoors and bagging all litter.

Chelsea - That's right. I know that many Naked Scientist fans are fond of composting, but I'm sorry to say that kitty litter isn't a good candidate for the compost pile because of these parasites. Our next story is about a scientist who has discovered a new way to get information out of some very old bones.

Bob - That's right and they're old as in prehistoric. You may remember in the movie Jurassic Park that scientists use ancient DNA to bring dinosaurs back to life. Well biogeochemist Peggy Ostrom from Michigan State University doubts DNA can last that long but she does think that she may be able to find and sequence the next best thing: dinosaur proteins. Her lab has already sequenced one type of protein in bones from a nearly 50 000 year old horse and a half million year old musk ox.

Peggy - SO that gives us some hope that we could push back the time limits in other fossils. So we're working our way back in time.

Bob - Proteins in dinosaur bones could tell scientists what dinosaurs ate and what diseases they had. And since proteins contain genetic information, they could also reveal new clues about how dinosaurs evolved.

Chelsea - Thanks Bob. Autism, Down's Syndrome and cerebral palsy are very different disabilities but one thing they have in common is that they make it harder to communicate through speech and that can make other things harder too.

Bob - That's right. Children with disabilities often fall behind in reading, writing and even social skills later on. But most speech therapy technologies are skewed towards adults. That's why Penn State University communication scientist Janis Light is leading an effort to re-tool them.

Janice - So our work has really looked at trying to develop computer technologies that are more appealing to young children that are really fun to interact with and at that same time to develop ones that are extremely easy for the children to understand and use. Our goal is that we would put a computer system in front of a child as young as a year of age or even younger and that from the moment they first see the computer system, that they would be able to interact with it and use it.

Bob - One strategy is to custom tailor the computers to each child's life. To hear the word 'dog' for example, the child might touch a picture of his or her own pet rather than a stock photo. The new systems have already helped disabled children learn language at near normal rates.

Chelsea - Well that's all for this week's Science Update from AAAS, the science society. Next week we'll be learning about a tiny plane that flaps its wings. Until then, back to you Naked Scientists.

- How To Turn Down The Heat of Climate Change

The Naked Scientists spoke to Anna Lacey interviews Professor Diana Liverman, University of Oxford

How To Turn Down The Heat of Climate Change
with Anna Lacey interviews Professor Diana Liverman, University of Oxford

Chris - Every single year in Cambridge they have a series of lectures called the Darwin lectures and this year they're on survival. The final talk in the series this year was by Professor Diana Liverman from Oxford University and she talked to Naked Scientist Anna Lacey about why ignoring climate change won't make the problem go away.

Diana - Climate change is a very serious threat to the survival of certain ecosystems and certain cultures. The reason it's a threat is that we now know that climate change is already occurring and we know that it's likely to occur more rapidly and more discontinuously than we think it's going to. It's also going to have serious effects on people in low lying coastal areas and for ecosystems that are going to have to change because of higher temperatures.

Anna - We've been hearing about things like this for years now and still we leave our televisions on standby and still we drive a mile down the road to the shops. How are you going to make people care about this?

Diana - That's a very good question. I think our challenge is to get over climate fatigue. People keep hearing about it and what we've got to say is that we now know something new and it really is very serious. In terms of what we've got to do about it, I do think that there's a lot that individuals need to do, but I actually think the government could do a lot more to help individuals respond. A lot of us might want to do things such as insulate our houses and buy cars with higher mileage per gallon, but we can't afford it or we would do better if there were some regulations or incentives to help us respond.

Anna - What about changing technology and new technologies like wind farms?

Diana - Technology is going to be a very important part of solving the climate change problem. The most obvious set are those concerned with efficiency and conservation. I drove here in a Toyota Prius.

Anna - Are these the type of car that have both electric and petrol?

Diana - Yes and they get pretty good fuel efficiency, but it's actually not their fuel efficiency, it's that they've got the lowest carbon dioxide emissions on the road. If the government puts in incentives then that's going to drive technological innovation and we'll get to a lower carbon future much faster.

Anna - But do you think that governments actually believe in changing climate, aside from all the things they say in parliament?

Diana - The British government I think believes in the problem but it's just that the decisions they've got to make, they don't seem to have the courage to make them at the moment. There's been a lot of things that have been done in the UK but it's not enough. We've got to get our emissions down by 60% is we're going to stabilise the climate. At this point, we're barely at about 13 or 14%.

Anna - But how on earth are we going to make up that massive gap?

Diana - I don't think it's enormously difficult but people need a little bit of financial help and a little bit of convincing in order to make those changes. So what we need is wise government to help push us in that direction.

Anna - And until the government actually sit up and really make a change, what can people do to help with climate change?

Diana - I would turn down your thermostat a couple of degrees, I'd switch all your appliances off standby and get on your bicycle.

- Is desalination the solution to water shortages?

With the ever increasing shortage of water in reservoirs, why can't we purify seawater to overcome the problem?

Is desalination the solution to water shortages?

The simple answer is that we can. However the problem is that it uses loads and loads of energy. There are two ways of doing it. You can either boil up the water into steam and then recondense it into water. Obviously that's going to use loads of energy, as you can see how expensive it is to boil a kettle. The other way of doing it is something called reverse osmosis. This is when you take a really fine filter and push the water through it. The salt then stays on the other side. This is a lot more efficient than boiling it, but it's still very energy expensive. Considering that the greenhouse effect is a big problem because we're using too much energy already, if started producing water by desalination in one way or another, we'd really be in trouble. There's no such thing energetically as a free lunch and what you're trying to do is take salt water which has a great concentration of minerals in it and separate those minerals into a strong concentration of minerals and a strong concentration of water. In other words, you've got to do work to sort the wheat from the chaff. That work comes at a high price. If we do it, we have to burn a fossil fuel in some way or another. The sun does that almost all the time all around the Earth. The sun is hitting the surface of the ocean, evaporating some water and leaving behind the minerals in the sea. The water forms clouds and then comes to Earth as precipitation. So the sun is desalinating all the time, but then the sun has money to burn.

- How many satellites are currently circling the Earth?

How many satellites are currently circling the Earth?

How many satellites are currently circling the Earth?

We've obviously got one natural satellite, our Moon. But we've actually launched around 8000 artificial satellites up into orbit around the Earth. However, that's not all there is orbiting around the Earth. As well as these 8000 solid lumps of whole satellite that are up there, we've got lots and lots of little bits of junk swirling around. Now that can be anything from a nut and a bolt that's been lost to astronaut gloves that have been lost during space missions. This stuff can actually be quite a problem, because as it's up there whizzing around at kilometres per second, if it hits another satellite it can seriously damage it and blow some more bits off. So all the time this stuff is accumulating, but there's no easy way to go up and remove it. Eventually all of it will slow down and fall into the Earth but it's up there for a long period of time.

- How do 3D glasses work?

How do 3D glasses work, and if you need these 3D glasses to appreciate the effect at the end, how do they produce them in the beginning?

How do 3D glasses work?

In 3D glasses, one lens is one colour and the other is another colour. Now when they project the film, they have a very powerful projector that projects two images side by side. One of the images is very slightly displaced from the other one. The reason for this is that you've got two eyes looking at the world and so you're getting two images of the world reaching your brain. These are slightly overlapping but separated by a small amount, or by the distance your eyes are apart. On the screen, they're projecting these two images: one in one colour and the other in a slightly different combination of colours. What your glasses do is to screen out the colours of one of the images while allowing the colours of the other image through. When your brain recombines them, it's seeing two different sets of images overlapping each other in just the right way to recreate a three dimensional image. If you shut on eye and move your head from side to side, the world looks slightly different. Things close to you move differently from things far away and that's one of the ways your brain judges how far away things are. The way they make the films is that they have two film cameras maybe six inches apart and that produces the same effect as looking through two different eyes.

- Which way does the Earth travel around the sun and is the sun spinning and moving too?

Which way does the Earth travel around the sun and is the sun spinning and moving too?

Which way does the Earth travel around the sun and is the sun spinning and moving too?

If you look at the Earth from above, then it's going around anticlockwise. Now the obvious question is 'which way is above in the vacuum of space'? How do you define that? Well if you're looking down on the Earth onto the North Pole it's going anticlockwise. The sun is also spinning. It goes around every few hours and is actually moving around through the galactic disk around the galactic centre. The galaxy is also spinning, so our sun is making a grand tour of the galaxy I think every few million years. Of course, the Milky Way is also moving through the Universe so everything is moving and it's all down to what you perspective is on that.

- What makes the Earth spin and will it ever stop?

What makes the Earth spin and will it ever stop?

What makes the Earth spin and will it ever stop?

The Earth has been spinning ever since it was created. It could have been because the Moon was created after a big collision with the Earth. If the collision was just off centre, then it would have spun the Earth really fast. When the Moon was created, it was really close to the Earth. The tides are actually slowing the Earth down. In fact, two hundred million years ago there were about 400 days in a year. This is actually a legacy of how all our planets formed because there was a big disk of material going around the sun and everything was spinning. As everything coalesced and formed planets, the conservation of momentum meant that they carried on spinning. This is the same principle as when an ice skater spins and brings their arms in and spins faster.

- Does the Earth attract a lot of meteor strikes?

We know that meteorites hit the Earth quite well. The sun is hundreds of thousands times bigger than the Earth, and so consequently I wou...

Does the Earth attract a lot of meteor strikes?

Well that's actually a really good question but there are a few effects that you need to take into account here. The Earth and meteorites are going around the sun and in different directions and at different speeds. Every now and again, you get a crossing of paths and one hits the other so we get a meteorite landing on the Earth. It's this crossing of paths that is more important than the gravity of the Earth itself. There have been a few near misses that nobody knew about until someone took a photo of the night sky and saw a meteorite. There are millions of little meteorites that hit the Earth all the time.

ecoRacing Car

- Where does all the rubber worn away from tyres go?

Whenever you replace tyres on your car, you notice that the tread has worn away. Where does all the rubber go? You don't see it piling up...

Where does all the rubber worn away from tyres go?

I've just been doing a quick calculation. If a tyre lasts for about five years, I reckon it comes out at about 10 000 tonnes a year of rubber in the UK. Tyres are actually really bad polluters because they don't only contain rubber but also a lot of heavy metals too. That's why when people say let's just burn old tyres, it's really bad because the toxins go up into the atmosphere and drop out into the soil that animals eat. If we focus on the US, 300 million people live there. Let's assume that they all have two cars per family of four. A car has four wheels, which means that in the US at any given time there are probably roughly 600 million tyres in use in any given year. Let's assume that the tread on a rubber tyre is 10 centimetres wide, the circumference of the wheel is 3 metres, and the thickness of the tread is about a centimetre. That means that the volume of rubber on a wheel and rubbing out is about 3 litres. If there are 600 million tyres and you times that by 3 litres, and then convert that to metres cubed, that's a staggering 2 million metres cubed of rubber every single year just in America. The density of rubber is 1200 kilograms per metre cubed. That means that there are 2 billion kilograms of rubber in tyres in the US. If you assume that they last for four years, that means that roughly two billion kilos gets lost or worn out every four years. That's a staggering amount.

- Does melting floating ice alter sea level?

If you get an ice cube and put it in a glass of water, when it melts it has exactly the same volume. This is the reason that when glacier...

Does melting floating ice alter sea level?

You're right for ice that's floating on water because it doesn't change the volume at all. But if you've got ice on Antarctica or the Greenland ice sheet where it's on rock and nowhere near the sea, when that melts, it will end up in the sea and increase the volume of the sea. Greenland is a massive ice sheet and there are tonnes and tonnes of water locked up as ice on land. The melting of ice on Greenland is raising the ocean depths by about half a centimetre every single year. If all that lot goes in the next 100 years, we could see a one metre rise in sea level.

- How does NASA send signals long distance into space?

As a radio amateur, I know that trying to get a signal very far away is hard unless the conditions are exactly right. How do NASA manage ...

How does NASA send signals long distance into space?

It's actually requires a lot of power. We use huge big radio dishes and they are metres across, if not nearly kilometres. We use a large number of these in order to communicate with spacecraft. There is a large time delay. I was involved with the Huygens mission which was at Saturn and there was a delay of a few hours for the data to get back to us. Because of that we had to use everything on remote and we got the data afterwards. We had no direct control while it was actually happening.

- When will New Horizons surpass Voyager as the farthest man-made object from Earth?

New Horizons is supposed to be the fastest spacecraft yet. I'm wondering when it will surpass the Voyagers as the farthest spacecraft fro...

When will New Horizons surpass Voyager as the farthest man-made object from Earth?

The easy answer is never because the New Horizons spacecraft is actually going to go into orbit around Pluto so it's going to stop there and isn't going to go any further out. But the Voyager spacecraft are actually at an immense distance away now. They're actually outside our solar system and in interstellar space, so we will be really hard pressed to get something out that far again. They really are the furthest thing that we've ever sent out into space.

- If you landed on an asteroid, would you have to hold on?

I have question about asteroids. If someone was to land on one, would they have to hold on like if they were on the edge of a car moving ...

If you landed on an asteroid, would you have to hold on?

You would have to hold on but not because it's moving but because the gravity is so low on an asteroid. In fact we've launched the Rosetta mission that's going to land on CG, which is its short name, and that's going to have harpoons on it to lock itself onto the asteroid. If it didn't then it would just float away.

- How do planetary rovers send signals back to Earth?

If it takes huge dishes to send signals into space, how do things like Venus or Mars rovers send their signals back when they send us the...

How do planetary rovers send signals back to Earth?

The reason why we use huge dishes is because the space probes use small dishes that send weak signals. They are even weaker by the time they get here, so we have to have big radar dishes to hear them.


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