# Douglas Adams was right, ish... Super-Earth world clocked orbiting 'nearby' Barnard's Star

A planet three times the size of Earth has been spotted orbiting Barnard's Star, one of the closest suns to our Solar System. Various science-fiction authors – notably Douglas Adams, Arthur C. Clarke and Michael Moorcock – have written about an alien world around Barnard's Star, which at six light years away is relatively …

1. #### Getting a proble there?

For some reason I still find it hard to believe currently available technology will allow a probe to reach 0.2c. And if that is possible, how will that probe decelerate and/or get results back to us?

1. #### Re: Getting a proble there?

The probe is powered by lasers on Earth driving the solar sail. You can flex the solar sail to modulate the lasers and then look at the reflection from the solar sails back to Earth.

As for deceleration, you might get far (no pun) by not bothering about that for the first probe, just send back some early data, just as for the probe to Pluto. It was all one intense flyby. If you want to decelerate you could do as described in Accellerando, where parts of the sail is detached, reflecting the laser light from Earth to the remaining sail attached to the probe, thus in a direction towards Earth.. The detached sail will accelerate but the probe will decelerate.

1. #### Re: Getting a proble there?

What if your vacuum is 100% - meaning: what if you hit something/something hits you at that speed?

Flying around for decades near the speed of light, I would assume that you got a good chance of hitting something eventually. ;-)

1. #### Re: Getting a proble there?

What if your vacuum is 100% - meaning: what if you hit something/something hits you at that speed?

It doesn't matter whether you hit it or it hits you. Even a tiny object like a Helium atom is going to have a lot of kinetic energy at relativistic speeds. IIRC Arthur C Clarke put a big block of ice out in front of his probes in "Songs of a Distant Earth" -- which remains about the only well thought out description of interstellar travel while complying with the laws of physics.

2. #### Re: Getting a proble there?

@_LC_

Well said.

Hitting a grain of dust at near light speed will be like an atomic warhead destroying the probe.

I have long thought the science fiction of cruising the galaxy in star ships is indeed fiction for just that reason.

1. #### Re: Getting a proble there?

Indeed.

The fastest man-made moving object is currently Voyager, and it's doing 0.00005c (3.6 AU/year).

It would need over 17,000 years to travel a light-year at that speed.

You just have to hope that space is incredibly empty.

1. #### Re: Getting a proble there?

"The fastest man-made moving object is currently Voyager, "

No it isn't. Parker solar probe is faster. 60km/s vs. 17km/s for Voyager.

http://parkersolarprobe.jhuapl.edu/The-Mission/index.php#Where-Is-PSP

https://www.space.com/42283-parker-solar-probe-closest-to-sun-record.html

2. #### Re: Getting a proble there?

"Re: Getting a proble there?

Indeed.

The fastest man-made moving object is currently Voyager, and it's doing 0.00005c (3.6 AU/year)."

I think you're confusing furthest man-made object with fastest.

https://www.jpl.nasa.gov/infographics/infographic.view.php?id=11489

1. #### Re: Getting a proble there?

The other objects are all in orbit around somewhere. It's cheating to consider orbit a speed, because then you get ridiculous values when planets are moving away from each other, etc.

The Pioneer's might qualify but seeing as we haven't contacted either in over a decade, it's pushing it. They were last doing 0.000041c and 0.000037c (same number of zeroes as Voyager).

Let me clarify: Consistent speed relative to Earth. That knocks all of the top 10 out.

2. #### Re: Getting a proble there?

I think your themysteriousworld website sprained my parser.

3. #### Re: Getting a proble there?

The Parker Solar Probe holds the current speed record -- at a 15-million-mile perihelion, it was going 213,200 miles per hour. (This is a bit over .0003 c.) It will get closer, and faster, each time it goes by (using planetary gravity assists). At closest planned approach, it will be 3.9 million miles away, which should bring its speed MUCH higher. But it's only doing that because it's very close to the Sun, and if you'd try to use that velocity to get to Barnard's star, it simply wouldn't be there. The probe would use it up trying to get away from our Sun.

2. #### Re: Getting a proble there?

hitting a mass of 1 gram at 0.2c would be like getting hit by around 60 kN of force. That's a decent amount (translates to about 13,500 lbs of force) but you're vastly exaggerating the effects.

3. #### science fiction

"I have long thought the science fiction of cruising the galaxy in star ships is indeed fiction for just that reason."

And rather short on science for that matter.

2. #### Re: "The detached sail will accelerate but the probe will decelerate"

Why ? This is space, there is no aether to decelerate the probe. The probe will continue at its speed, and the sail, being pushed by the laser, will accelerate further and go faster than the probe.

But the probe has no reason to slow down simply because it detached from its sail.

The only way for the probe to slow down is to have a mass drive of some sort that exerts the necessary pressure in the right direction to slow it down.

1. #### Re: "The detached sail will accelerate but the probe will decelerate"

"Re: "The detached sail will accelerate but the probe will decelerate"

Why ? This is space, there is no aether to decelerate the probe. The probe will continue at its speed, and the sail, being pushed by the laser, will accelerate further and go faster than the probe.

"

Because they are proposing two sails - one that is detached, and still accelerated by the earth bound laser, and one which is pushed by the light reflected from the detached sail...

That would be a retarding force.

Unfortunately I don't think that we could target one of the two sails from here, so we'd likely hit the 'back' back of the 'braking' sail, and accelerate it instead... Additionally the accuracy with which the second sail would need to be positioned for reflected momentum to target the prove would be insane.

1. #### Re: "The detached sail will accelerate but the probe will decelerate"

The trick of using part of the sail to decelerate the remainder was devised by Robert Forward, and detailed in his novel Rocheworld about a crewed voyage to Barnard's Star.

He even found a way to bring the ship back again, still using only the Earth-based lasers.

His scientific paper describing the system seems to be behind a paywall, but here's the abstract

2. #### Re: "The detached sail will accelerate but the probe will decelerate"

"Because they are proposing two sails - one that is detached, and still accelerated by the earth bound laser, and one which is pushed by the light reflected from the detached sail...

That would be a retarding force.

Unfortunately I don't think that we could target one of the two sails from here, so we'd likely hit the 'back' back of the 'braking' sail, and accelerate it instead... Additionally the accuracy with which the second sail would need to be positioned for reflected momentum to target the prove would be insane."

I would have thought you'd stand more chance just blasting the sails themselves out of the front, if you're detaching them anyway. Shove some lead on them if they need to be heavier, and turn up the intensity of the laser if necessary.

2. #### Re: "The detached sail will accelerate but the probe will decelerate"

The idea is only to detach one part of the sail. The laser will still hit that part and accelerate it further. But the laser is being reflected from the detached part and hits the probes remaining sail from the front, which decelerates the probe. But this would be a highly complicated stunt given the differences and the communication latency of 12 years. You could just pre-program the procedure and fire the laser at the right time (six years earlier) in the hope that everything is where is should be. And this simple calculation doesn't even include relativity, which will already play a big role at 0.2c,

1. #### Re: "The detached sail will accelerate but the probe will decelerate"

"The idea is only to detach one part of the sail. The laser will still hit that part and accelerate it further. But the laser is being reflected from the detached part and hits the probes remaining sail from the front, which decelerates the probe. But this would be a highly complicated stunt given the differences and the communication latency of 12 years. You could just pre-program the procedure and fire the laser at the right time (six years earlier) in the hope that everything is where is should be. And this simple calculation doesn't even include relativity, which will already play a big role at 0.2c,"

I get the idea. I just think it's stupid. First, the laser hitting the detached sail will push it forwards and the probe backwards (assuming it works), so the sail will need some sort of power of its own to continually readjust the focus of the reflection. Second, we'll worry about how narrowly focused the laser beam needs to be to hit a single object (and not the probe's sail) from six light years away, sent six years ago based on where you think the probe will be. Then, as you say, the fact that you've already pushed the probe to 0.2c makes slowing it down harder as it's now heavier.

This is why I suggest chucking the whole sail and everything else you don't immediately need out the front, or equivalently just firing the whole recording equipment out the back of the probe when you get there would decelerate it more. If it's going at 0.2c, I reckon that will get it down to about 0.19999c, maybe a bit more. Which is still better than the sail detachment idea.

Also, suppose you can accelerate a 1kg probe to 0.2c in six months of laser shining. I reckon that the power requirement is 0.2^2c^2/2/180/24/3600 (0.2^2c^2/2 is the kinetic energy of the probe), which means the laser needs to be about 1GW in power, after heat loss from the atmosphere. And that ignores relativistic effects: both special and general. (The special effect is the mass of the craft getting heavier, so we need to add that into the calculation. The general effect is the loss of power due to gravity on the laser itself, as it will still have to leave the Earth's gravity well. You can build a space-based laser, but on order to harvest 1GW from the sun, well, it's going to have to be big. Something like 3-4sq km.) Chinny reckon.

3. #### Re: "The detached sail will accelerate but the probe will decelerate"

Accelerando was mentioned. I can make a drawing. What is the Reg approved image hosting site?

4. #### Re: When there's no more magic left it's time to stop.

Robert Forward, who was a professional physicist and science fiction author used described the deceleration of a laser powered space ship in his Rocheworld books.

5. #### Re: "The detached sail will accelerate but the probe will decelerate"

"Why ? This is space, there is no aether to decelerate the probe. The probe will continue at its speed, and the sail, being pushed by the laser, will accelerate further and go faster than the probe.

But the probe has no reason to slow down simply because it detached from its sail."

That was also my first take. Then on careful re-reading : "parts of the sail is detached, reflecting the laser light from Earth to the remaining sail attached to the probe," the idea is to detach one of the sails and keep aiming the laser at it and not at the sail attached to the probe. So probe would go on at same velocity, detached sail would accelerate past the probe. Then when detached sail is far enough in front of the probe, reflect laser from the detached sail towards the forward surface of the sail still attached to the probe, which will decelerate the probe.

And my take on that was: "Holy crap, no effing way!". The theory is nice, but hitting a probe's sails (few hundred m at most?) millions of km away with a laser is hard enough. Hitting one specific sail but not the probe on the main beam AND hitting the probe's sail with the reflected beam is so far beyond our engineering capabilities as to be truly science fiction.

3. #### Re: Getting a proble there?

Am I missing something here? There are no fixed points in space and light is notorious for wanting to travel in straight lines. How do you keep a terrestrial based laser targeted at sails on a probe? Especially when, say, the Sun is between the Earth and the probe.

2. #### Re: Getting a probe there?

Maybe not quite today's technology but certainly in the near future and most likely using Ion Drive propulsion systems.

As for getting the information back they will use radio waves, which will take 6 years but better than 30.

Unless they are able to use something like quantum entanglement, which means essentially real-time communications may become possible.

1. #### Re: Getting a probe there?

As I understand it (or not) quantum entanglement does not provide faster-than-light communication.

http://curious.astro.cornell.edu/our-solar-system/the-earth/137-physics/general-physics/particles-and-quantum-physics/810-does-quantum-entanglement-imply-faster-than-light-communication-intermediate

1. #### Re: Getting a probe there?

Fair point!

Back to the drawing board I guess!

2. #### Re: Getting a probe there?

As I understand it (or not) quantum entanglement does not provide faster-than-light communication.

http://curious.astro.cornell.edu/our-solar-system/the-earth/137-physics/general-physics/particles-and-quantum-physics/810-does-quantum-entanglement-imply-faster-than-light-communication-intermediate

While I wouldn't want to make a pronouncement on the possibility of faster than light or not of quantum communication (a subject even Einstein could get things wrong about: see John Bell), that explanation slightly dodges the quantum communication aspect of the question.

Undoubtedly, as in the description, if you tell two friends that you'll send them light beams of red and blue, send them off in different directions and then send the light beams, 1. they will know the other person's colour before the other person could communicate the signal to them, 2. the information conveyed only travelled out from you at c (which choice you made about who to send what colour) and <c (the setup in the first place). In a quantum context that choice about red or blue is representing the outcome of state collapse (if you believe in state collapse), which is generally thought to occur at the time of measurement. So the explanation is, in a way, a hidden variable explanation. If that hidden variable doesn't exist, then the outcome for Alice determines the outcome for Bob at the time the measurement is made.

The quantum entanglement part is this: Alice and Bob head out with entangled particles. Measurement on a particle collapses the waveform and you know from the answer what answer the other person will get. However, that's not how you intend to communicate. How you want to communicate is in deciding how to make the measurement.

Say instead of two colours we have four. Blue, green, red, yellow and Alice and Bob can both measure for either blue/red or green/yellow. If A measures for blue/red and Bob measures for blue/red they will always get opposite answers (as before). Same if they both measure for green/yellow.

Now imagine that I'm actually sending purple and orange. Purple shows up as red or green, orange as blue or yellow (you'll notice this isn't a lecture on colour theory). If A and B make the same measurement then when they compare later they get compatible answers. If they make different measurements then they can still work out what the other person would have got if they knew what the measurement was. My purple/orange choice is a hidden variable.

But this isn't what happens with entanglement. A measures r/b, and gets an answer. B measures g/y. No matter what answer A got, B has a 50:50 chance of g or y, the measurements are independent. Even if they make the measurements at the same time or at an interval shorter than the time light can travel between them. It's not just a case of the blue going one direction and the red going the other (in which case you could assume there's some hidden variable), it's that the measurement A chooses to take appears to influence the answers B can get instantly. This gives rise to the Bell inequality https://en.wikipedia.org/wiki/Bell%27s_theorem and one of the great missed Nobel prizes.

But, for communication of information it's no good. From B's point of view, while their answer does depend on the measurement A made, they can't tell which answer A actually got. And this is also due to the "state collapse" (probably it doesn't) part of the entanglement. If A always got red when measuring r/b and green when measuring g/y then you can construct a noisy channel (this is just off the top of my head, probably a more efficient way):

A sends "1", by reading in r/b requires four measurements:

A -> B

r -> (r/b) b

r -> (r/b) b

r -> (g/y) g

r -> (g/y) y

Note the first two results would be fixed, the second are 50:50 different.

Similarly A could send "0" by making four g/y measurements. Now the first two b measurements would be 50:50 to be different and the second two would be yellow. So you have to discard 50% of these quartets, but the others you know what the original measurement was.

But you can't do this either, and the reason is that you can only be in one pair of states. It's perfectly possible to have a deterministic "A always gets red when measuring r/b", we could do that with the lights example. But you can't simultaneously have the full set: "A and B get different answers", "A always gets red if r/b", "B gets 50:50 g/y if A measures r/b" and "A always gets g if A measures g/y", because of the symmetry of the entanglement. So though something is going on, the way the statistics work mean you can't use it until you compare the answers A and B got.

(I mentioned being dubious about state collapse, weak measurement experiments suggest it doesn't happen. If Alice believes Hugh Everett, she has gone out of phase with the Bob who measured red after she did, and can therefore never meet him again to compare notes.)

1. #### Re: Getting a probe there?

massive comment that got away from me

If you think that was long, you could try reading https://en.wikipedia.org/wiki/No-communication_theorem

2. #### Re: quantum entanglement ... real-time communications may become possible.

Not under QM as it stands. Whilst you might argue that some kind of influence travels faster than light, no usable information does. To transfer information you need the measurement results at *both* ends,

and that from the far end still has to travel to you at the speed of light.

3. #### Re: Getting a probe there?

>As for getting the information back they will use radio waves, which will take 6 years but better than 30.

Has a decision been made? It would after all require a reasonably directive antenna, otherwise the received signal strength will be far to low to decode. Optical bands are more attractive since divergence is small for a small aperture, though you have to use a band that is not swamped by the star.

As for ion drive, where do you propose to get the energy from? Or how do you keep the weight down? The huge advantage about laser propelled sails is that the power is expended on Earth leaving a very light weight probe that can be accelerated hard.

And even if you had a local power source it would take a long time to decelerate from near light speed to in system orbital speed.

1. #### Re: Getting a probe there?

I suggest you direct your excellent questions to Elon Musk who will provide a collection of facile and only mildly improbable answers as well as an opportunity to invest in his new Barnard or Bust company, a free (after shipping and handling) flamethrower, and a 97% off if you promise to stay over a Saturday night round trip coupon for the Barnard Express that BoB plans to launch in 2027. I suggest that you pass on the flamethrower. It can only get you in trouble. But keep the coupon. It might actually have some value someday although I can't see how.

1. #### Re: Getting a probe there?

"I suggest you direct your excellent questions to Elon Musk who will provide a collection of facile and only mildly improbable answers"

He'll probably call you a 'pedo' actually for saying his stupid invention won't work.

2. #### As for ion drive, where do you propose to get the energy from?

Nuclear power plant.

1. #### Re: As for ion drive, where do you propose to get the energy from?

If you can use a planet's gravity to slingshot (i.e. accelerate) a probe, why couldn't you use one to slow it down too?

All you do is fly AGAINST the motion of the planet, rather than with it.

Sure, the maths is damn hard, and you'll want to make sure you have a good view of the planet / system in question long before you need to do the manoeuvre but there's no reason you can't use the same trick we use to launch probe quicker and further than ever before (Voyager) to slow them down at the other end in the same way.

Literally... fire it towards the planet "in front" of it, by millions of miles to be safe... aim it at the planet, as the planet flies past, it drags it back a little, slowing it. Take some photos while you're there. Readjust the orbit as you leave (because you'll now be in an elliptical that includes the planet's position, so you'll go out of the system, and then come back in towards it for another go) and keep doing that until you're in a perfectly circular orbit.

It's the kind of celestial mechanics that you can leave a computer to do nowadays, just updating it with more accurate observations as you get closer, and it'll work out an orbit with however many dozen deceleration slingshots you want until you get to a nice stable orbit. Minimal thrust to adjust the orbit would be required, and presumably you'd be in range of a whole new sun or still be powered nuclearly by that point.

You never go TO the planet, you go past it, let it swish you back around, have another go, and another and another and another. It's perfectly viable and we did it around Mars for every launch - nobody's yet invented vacuum-brakes or a way to get geostationary (or even stable) orbit perfect first time from millions of miles away in a straight line.

1. #### Re: As for ion drive, where do you propose to get the energy from?

If you can use a planet's gravity to slingshot (i.e. accelerate) a probe, why couldn't you use one to slow it down too?

Periapsis burns are standard practice for capture. Cassini and Galileo both depended on planetary gravity to help their captures.

1. #### Re: As for ion drive, where do you propose to get the energy from?

"Periapsis burns are standard practice for capture. Cassini and Galileo both depended on planetary gravity to help their captures."

Shhhhh don't tell NASA, the last time they tried this on MARS they got their Freedom Units mixed up and hit the planet hard

1. #### Re: Getting a proble there?

The problem of course selection for optimal observation and of signal integrity back to Earth both have the same solution.

Don't send one probe.

Send a probe, then next year send another one* and then another and so on so you have a chain, when the first one arrives it makes simple observations so the following ones can alter course to make a better observation which can instruct the next ones and so on.

For signals each probe acts as a repeater sending the signal to the probe behind it.

* Actually it might be easier to launch them all at once but give them slightly different speeds so they form a chain that way.

2. #### Re: As for ion drive, where do you propose to get the energy from?

You can use it to slow you down, but not enough. To get into an orbit around the planet you need to leave it on the first pass with less than its escape velocity, and given you are approaching it at a significant fraction of the speed of light you can't do that.

Need a VERY big dish... not impossible, but a transmission from the probe that can be received here is a challenge as big as getting the probe there. Not sure if a laser solves issue. We could use a magnetron transmitter with maybe 1kW input giving 20kW pulses. Not sure were the power would come from for a CW transmitter.

>Need a VERY big dish

We send a Von Neumann device, which builds a dish when it gets there...

5. #### Re: Getting a probe there?

Quantum entanglement -- quantum anything in fact -- does not mean real-time communication is possible and there is no suggestion that it ever will. Please don't spread this silly myth.

3. #### Re: Getting a proble there?

IMHO one issue would be having good enough orbital data to perform a flyby within a useful distance - it's pretty useless if you pass when the planet is on the other side of the orbit - and the higher the speed, the less time to perform corrections.

Some kind of deceleration could be required - passing at 0.2c won't give much time to collect data, while transmitting them back will require not little power, which must be generated somehow.

4. #### Re: Getting a proble there?

Yes, with current tech we can get up to an appreciable percentage of lightspeed. Speed is money, how fast do you want to go? As for brakes, who needs brakes? Snap a few pics on the way through and send 'em home with a narrow beam antenna set to repeat indefinitely or until another solid(ish) object is detected. Lather, rinse, repeat. We'll pick up enough bits to reassemble the pictures eventually.

5. #### Re: Getting a proble there?

As for getting results, it could still use a radio transmitter with a big parabolic dish antenna. I'm sure it would use RTGs similar to the other deep-space probes to power the transmitter (and everything else), probably the tried-and-true Pu238 RTGs that were used in Voyager and Pioneer with half-life of 87.7 years. That bit doesn't seem so far fetched. It is the propulsion system that I doubt. 0.2c is two orders of magnitude faster than the fastest spacecraft thus far deployed.

2. #### Probe

The probe would find that the Vogons had got there first and demolished the planet so that Amazon could build its new orbital Galactic HQ in its place.

1. #### " new orbital Galactic HQ"

Woudn't be it on Trantor - or be it Trantor, in Bezos' planning?

1. #### Re: " new orbital Galactic HQ"

Coruscant would be more logical then. Capital of the Star Wars evil empire.

1. #### No

That one's reserved for Uber.

3. #### Shame the em drive never worked out

The thing with trying to slow down again after picking up all that speed is that halfway along you have to do a 180 turn and burn in reverse to slow down. Now if we knew every planet and celestial body floating around the star then we could use gravity to show down instead but then this would involve either the probe being smart enough to do the calculations or us fleshies telling it what to do. Great if we can talk instantly, not so great if we have to rely on the fastest thing there is (speed of light in a vacuum)..

1. #### Re: Shame the em drive never worked out

The fastest thing there is is not the speed of light in a vacuum, but a hire car. Any fool knows this... :-)

1. #### Re: Shame the em drive never worked out

go everywhere in 2nd.

all the time.

2. #### Re: Shame the em drive never worked out

So Tesla in Space might be the first hire car?

1. #### Re: Shame the em drive never worked out

"So Tesla in Space might be the first hire higher car?"

FTFY

2. #### Re: Shame the em drive never worked out

> "Now if we knew every planet and celestial body floating around the star then we could use gravity to show down instead..."

No we can't. Such a high-speed probe would not be close to any large mass long enough to dump a significant amount of velocity. Maybe its path would be bent slightly, but that's all.

BTW, obligatory Banard-related XKCD (published 22 Oct, 2018!)

4. #### Freedom Units

I like it :-)

Stand by for a shit storm from unimaginative pedants without a sense of humo(u)r, though. Poor bastards.

1. #### Re: Freedom Units

Fake Degrees?

2. #### Re: Freedom Units

Freedom units are all well and good, but El Reg temperature standard is the Hilton, and -150C is -17 Hiltons. Has the Vulture Central Standards Bureau been disbanded?!

1. #### Re: Freedom Units

The standard number of time the register actually references reg standard units has been declared as once per 17 months, 4 days and the time it takes to cook a penguin burger from frozen.

1. #### Re: Freedom Units

Penguin meat doesn't freeze. Besides, it tastes fowl.

5. #### Does the observation match somehow van de Kamp data?

I would find interesting it van de Kamp data were actually real and within a good enough match of these new data, and not an error of his observations.

6. #### We're not thinking this through...

What we do is, we *launch* it using a 'leave your engine at home' laser/light sail drive, adding engines as it gets further away so we don't melt the sail.

Then the locals, seeing the blue-shifted reflection of their sun coming down their throats, send out some young buck who will catch the probe in a spare airlock, while simultaneously diving toward's Barnard's star at to match velocities... oh, wait, that's the way the *Moties* do it. We have to think of something else.

7. #### Jack Vance?

Didn't Jack Vance had some conclave on barnard's star where the devil princes divided the realm?

1. #### Re: Jack Vance?

Probably.

8. This post has been deleted by its author

1. @ 89724102172714182892114I7551670349743096734346773478647892349863592355648544921

Are you trying to accumulate the most down votes in the history of The Register?

1. @ 89724102172714182892114I7551670349743096734346773478647892349863592355648544921

Are you trying to accumulate the most down votes in the history of The Register?

Only 5 after an hour? Seems he failed that as he did his Adams trivia GCSE - everyone knows Adams writing was fueled/procastinated over by numerous baths. Really not sure if he was hydroelectrically powered/fusion powered or nuclear and needed the baths to cool down.

2. #### Easier to call it "I".

Just sayin' ...

9. #### Freedom Units?!

Oh her her... My aren't we witty today.... FYI Bush Jr. was 11 Years ago. Next time try a joke that doesn't smell like a dead Fish.

10. #### Let's call it Rura Penthe

The description fits.

11. #### Frontier Elite 2

Its times like this why I fire up Frontier Elite 2 (now playable in a web browser at https://www.myabandonware.com/game/frontier-elite-ii-22i/play-22i )

My star system information says that its a stable system with 10 bodies, the largest being Barnards Star 3 - 2.14 Earth masses, but with a methane weather system and corrosive atmosphere, surface temperature -149'c.

1. #### Re: Frontier Elite 2

Thanks for the link Andy. Have an upvote . PP

12. #### What's the Gravity on it?

I imagine I used to know how to work out surface gravity based on mass. Unfortunately, I finished my A levels 40 years ago and have become ignorant!

1. #### Re: What's the Gravity on it?

@Spanners

On Earth, the weight of a unit mass is GM/(R**2).

This becomes proportional to GM**(1/3).

The new exoplanet is described as 'rocky', with mass at 3.2*M. If its average density is similar to Earth, gravity at its surface will be greater by 1.47. But who cares about gravity if you live in an ocean?

13. #### Improving Telescopes

We can’t currently “see” the planet, but as time and technology moves on, no doubt we will have powerful enough telescopes to be able to zoom in. What will we see?

Probably a message written in fire in letters thirty feet high:

“We apologise for the inconvenience”

1. #### Velve re “We apologise for the inconvenience”

OR

"Make no landings here". PP

1. #### Re: Velve re “We apologise for the inconvenience”

My money's on "Google" or "Facebook" ... unless CocaCola got there first.

14. #### Who cares - red dwarf stars are a-holes

Isn't it true that the periodic and insanely hot flares from red dwarf starts make it impossible for life to survive in these systems?

15. #### I’m feeling too lazy to look it up..

But I’m Pretty sure Douglas Adams never mentioned a planet around Barnards star, it was just the next hyperspace ’jump’ location for the Vogon ship after destroying Earth (spoiler). IIRC it was equated to the Guildford roundabout in hitch hiking terms.

16. #### Fascinating discussion about how to slow down a probe 6LY distant...

... but I don't see anyone addressing the question of WHEN to do so.

We're talking about a star system that is so far away that we're really only guessing at the distance and a probe being sent to investigate a planet that we only think is there but have no data for exactly where, let alone projecting where precisely (or even approximately) it will be at the time that the probe arrives.

Even if the distance calculation is accurate, and in astronomical terms might be considered "good enough", once you're in the locality you need to be assuredly more precise. In the same way that if I were to send a package from here (Auckland) to a friend back in the UK, just saying "Please take this package 18,360km that-a-way" (points toward London) is not going to result in a successful delivery or even arrival in the right county, let alone town.

Any probe will need to be fully autonomous, able to determine it's arrival at the star system, identify and locate any and all planetary bodies and perform the calculations necessary to either achieve a stable orbit around any particular thing of interest, avoid missing everything of interest and sailing on past into the void or (irony of ironies) avoid colliding with the very thing it has been sent to probe (or something else that we haven't yet determined existence of from our current, remote observation station).

And it needs to be able to choose when and where to perform any delta-v itself. Anything reliant on Earth-based technology (requiring data to be sent to Earth and then commands or laser light destined for any sails sent back to the probe) would result in that delta-v occurring almost 12 years too late.

1. #### Re: Fascinating discussion about how to slow down a probe 6LY distant...

So, the probe needs some sensors and a copy of Kerbal Space Program?

17. #### Why did it take 21 years to confirm the planet?

The star is very close, dim, low mass and the planet is high mass. That seems to be ideal for planet detection. Yet we've found thousands of planets much further away orbiting much brighter stars. Can someone explain the seeming contradiction?

1. #### Re: Why did it take 21 years to confirm the planet?

There is simply a lot of space to look at and relatively few eyes doing so.

18. #### Could a human even survive the gravity..

Of such a planet that size, it is hard to imagine what a (100 lb. on earth) man would weigh on the surface.

1. #### Re: Could a human even survive the gravity..

It is 3x the diameter, so if the density is the same you'd weigh 3x as much. It would put quite a strain on you, but you could survive it if you were in really good shape. Not a good destination for couch potatoes!

You'd need some sort of artificial gravity for the LONG trip over to avoid losing a bunch of bone density and muscle mass. Assuming that was done via rotation you could slowly increase the rotation during the trip to help acclimate yourself slowly rather than being dumped into 3x gravity all at once.

1. #### Re: Could a human even survive the gravity..

The real problem is not weight, it's reflexes. The acceleration due to gravity will be higher than "earth trained" reflexes can handle. Falls will probably be a primary source of fatal injury at 3g ... and forget about playing ball and stick games at anywhere near a professional level (except snooker, billiards etc.).

## POST COMMENT House rules

Not a member of The Register? Create a new account here.