Radioactive Thermal Generators (RTG's) require a large thermal gradient to function efficiently - they make use of large banks of thermocouples to directly convert heat to elctricity - they also require shielding to protect the electronics and spacecraft systems from radiation - usually by putting the thing on a boom out away from the main body of the craft - RTG's are also fairly heavy (nuclear fuel is denser than lead) and not desirable for a craft that must land. All and all if you have bright enough sunlight - solar cells are probably the best alternative.
I seriously doubt that this design would offer "continous" coverage over 650 sqaure miles - as the parent post mentioned thats like a 5 mile range on each AP - to get that kind of range would require directional gain antennas AND/OR illegal linear power amplifiers - the multipath effects would be terrible in an urban environemnt especially at the overlap regions between AP's. And Lord help you if someone fires up a microwave oven or a cordless phone:-)
Here is an ADC (dual actually) and an FPGA to do the decoding for you:-) you still need to mix down the 2.4 GHz but that is pretty easy and inexpensive - this one is fast enough that if you were nuts enough you could create your own software radio with it (its a nice card with good VHDL support) Benadda dual AD DA card And I agree with you it is a cool idea !
Kind of off topic BUT since you brought it up you don't need liquid nitrogen to do that - we were able to use a really nice spectrum analyzer to downconvert (mixer output) the 2.4 GHz RF signal to baseband and then decoded it with a pretty modest A/D converter (11 Mb/s aint that fast). But even that was overkill we just wanted to be able to see the bits flipping:-)
What about all the other Operating Systems that currently work on Intel platforms like VxWorks and QNX, With the significant effort (and money) required to use custom RT OS's with Intel hardware I can see this is going to be a major reason to NOT go with Intel hardware and stick with Motorola PPC based products.
What about the first moon landing ? Neal Armstrong took control due to a computer malfunction that put the LEM off course - he successfully landed the Eagle in NO Atmosphere - in a craft designed before most of the people posting on Slashdot were born...
An absurd gift, An Amish man (beard, hat etc..)puppet who's spring loaded arms can pack quite a nice hit - A completely bizarre gift from my equally bizarre sister... The company that makes it also makes a Nun punching puppet...
I think thats a poor comparison - the Beagle 2 is a very low cost probe ad so are its landing systems - I don't believe we will ever use bouncing balls for a manned landing and a human is a much more adaptable landing computer than any automated system we could build (yet).
not new here... I just hit my breaking point with this story, I guess the Christmas holiday has me kind of edgy and I didn't get enough caffeine today....
I am so sick of the how the stories that get posted on Slashdot always have some wording to get this site going on a political bent. This story could have stimulated some interesting technical discussion - but because it had a tag line that mentioned the French / American thing, it will degrade into yet another Slashdot American / European / Asian / etc. bashing.... Please PLEASE keep it about "News for Nerds" and "Stuff that Matters"
"Feathering" as in the feathers on a badmitton shuttlecock - basically it makes the whole aircraft very very draggy (which obviates the need for ablative coatings or heat tiles) and also stable by moving the CG of the aircraft in a predictable manner (again just like a shuttlecock will always eventually end up with the feathers up and nose down)- the feathering feature is not used during powered flight as far as I know.
In this case they are - Spaceship One is a glider with a rocket engine. I was fortunate enough to personally see Mike Melville pilot the Spaceship One back in November during a test of the feathering feature - I saw him dive the aircraft and then pull it up until it stalled (planned) and then effortlessly recover and glide into a perfect landing in Mojave - Spacehip One is one heck of an "aircraft" but its also tight and strong enough to survive the vacuum of space.
Congratulations Scaled Composite's and Burt Rutan you guy's are truly making history !!
I agree that for some purposes its a neat idea - BUT I for one find it very annoying to listen to someone's loud walkie-talkie conversation - in the mall, at airport, eating out - ugghhh. Please put your ear bud in and talk softly so the rest of us don't have to listen to your conversation about your colonoscopy.
You are partially correct the laser was "officially" invented in 1958 - however the maser was invented in 1953 (microwaves instead of visible light) The laser was at the time a predictable outgrowth - and was theorized to be possible. The patent in question mentions radiation in general, as well as lasers radiation. So while it seems amazing that somone could have that much foresight, its not improbable.
I have used QNX and I can tell you it is great for embedded systems - it is like an affordable VxWorks - a real time OS with lots of bells and whistles and super stability. However like VxWorks it does lack a lot of hardware support - but you can write your own drivers (of course). You use to be able to download the OS for free for evaluation in a single executable that runs kind of like Knoppix - no real install necessary. Its a cool way to kill an afternoon if your bored (and a geek).
30 satellites is a full Galileo constellation, it needs more because the orbits are lower than the GPS constellation - any positioning system however really only needs 3 or 4 birds visible for a 3D solution, many systems can create a composite solution of up to 12 birds (all that are visible). And FYI there are 24 GPS satellites in a full up GPS constellation not 3. GPS works globally, it has not had any limitations on latitude since ~ 1995 (a little earlier actually)when it went FOC. Galileo will have similar limitations until the entire constellation is in orbit.
Slashdot Mirror
Radioactive Thermal Generators (RTG's) require a large thermal gradient to function efficiently - they make use of large banks of thermocouples to directly convert heat to elctricity - they also require shielding to protect the electronics and spacecraft systems from radiation - usually by putting the thing on a boom out away from the main body of the craft - RTG's are also fairly heavy (nuclear fuel is denser than lead) and not desirable for a craft that must land. All and all if you have bright enough sunlight - solar cells are probably the best alternative.
I seriously doubt that this design would offer "continous" coverage over 650 sqaure miles - as the parent post mentioned thats like a 5 mile range on each AP - to get that kind of range would require directional gain antennas AND/OR illegal linear power amplifiers - the multipath effects would be terrible in an urban environemnt especially at the overlap regions between AP's. And Lord help you if someone fires up a microwave oven or a cordless phone :-)
Here is an ADC (dual actually) and an FPGA to do the decoding for you :-) you still need to mix down the 2.4 GHz but that is pretty easy and inexpensive - this one is fast enough that if you were nuts enough you could create your own software radio with it (its a nice card with good VHDL support)
Benadda dual AD DA card
And I agree with you it is a cool idea !
Kind of off topic BUT since you brought it up you don't need liquid nitrogen to do that - we were able to use a really nice spectrum analyzer to downconvert (mixer output) the 2.4 GHz RF signal to baseband and then decoded it with a pretty modest A/D converter (11 Mb/s aint that fast). But even that was overkill we just wanted to be able to see the bits flipping :-)
What about all the other Operating Systems that currently work on Intel platforms like VxWorks and QNX, With the significant effort (and money) required to use custom RT OS's with Intel hardware I can see this is going to be a major reason to NOT go with Intel hardware and stick with Motorola PPC based products.
Back for a return engagement..
Around the World in a Solar Plane
I guess an army of Amish punching puppets would be quite an extraordinary force :-)
Thanks for the laugh this morning...
What about the first moon landing ? Neal Armstrong took control due to a computer malfunction that put the LEM off course - he successfully landed the Eagle in NO Atmosphere - in a craft designed before most of the people posting on Slashdot were born...
An absurd gift, An Amish man (beard, hat etc..)puppet who's spring loaded arms can pack quite a nice hit - A completely bizarre gift from my equally bizarre sister... The company that makes it also makes a Nun punching puppet...
I think thats a poor comparison - the Beagle 2 is a very low cost probe ad so are its landing systems - I don't believe we will ever use bouncing balls for a manned landing and a human is a much more adaptable landing computer than any automated system we could build (yet).
not new here... I just hit my breaking point with this story, I guess the Christmas holiday has me kind of edgy and I didn't get enough caffeine today....
I am so sick of the how the stories that get posted on Slashdot always have some wording to get this site going on a political bent. This story could have stimulated some interesting technical discussion - but because it had a tag line that mentioned the French / American thing, it will degrade into yet another Slashdot American / European / Asian / etc. bashing....
Please PLEASE keep it about "News for Nerds" and "Stuff that Matters"
"Feathering" as in the feathers on a badmitton shuttlecock - basically it makes the whole aircraft very very draggy (which obviates the need for ablative coatings or heat tiles) and also stable by moving the CG of the aircraft in a predictable manner (again just like a shuttlecock will always eventually end up with the feathers up and nose down)- the feathering feature is not used during powered flight as far as I know.
In this case they are - Spaceship One is a glider with a rocket engine. I was fortunate enough to personally see Mike Melville pilot the Spaceship One back in November during a test of the feathering feature - I saw him dive the aircraft and then pull it up until it stalled (planned) and then effortlessly recover and glide into a perfect landing in Mojave - Spacehip One is one heck of an "aircraft" but its also tight and strong enough to survive the vacuum of space.
Congratulations Scaled Composite's and Burt Rutan you guy's are truly making history !!
more importantly can you make a Beowolf cluster of them :-)
nuff said...
Just for reference an ancient Boeing 707 can do .85 mach or better.
don't mean to be an a-hole - but that's what the TM in superscript next to the words "Direct Connect" mean (registered Trade Mark)
I agree that for some purposes its a neat idea - BUT I for one find it very annoying to listen to someone's loud walkie-talkie conversation - in the mall, at airport, eating out - ugghhh. Please put your ear bud in and talk softly so the rest of us don't have to listen to your conversation about your colonoscopy.
You are partially correct the laser was "officially" invented in 1958 - however the maser was invented in 1953 (microwaves instead of visible light) The laser was at the time a predictable outgrowth - and was theorized to be possible. The patent in question mentions radiation in general, as well as lasers radiation. So while it seems amazing that somone could have that much foresight, its not improbable.
I have used QNX and I can tell you it is great for embedded systems - it is like an affordable VxWorks - a real time OS with lots of bells and whistles and super stability. However like VxWorks it does lack a lot of hardware support - but you can write your own drivers (of course). You use to be able to download the OS for free for evaluation in a single executable that runs kind of like Knoppix - no real install necessary. Its a cool way to kill an afternoon if your bored (and a geek).
Thanx everywun for prooving meye poynt :-)
Sentient Meat
your wrong - there are no planets with intelligent life...
nuff said...
30 satellites is a full Galileo constellation, it needs more because the orbits are lower than the GPS constellation - any positioning system however really only needs 3 or 4 birds visible for a 3D solution, many systems can create a composite solution of up to 12 birds (all that are visible). And FYI there are 24 GPS satellites in a full up GPS constellation not 3. GPS works globally, it has not had any limitations on latitude since ~ 1995 (a little earlier actually)when it went FOC. Galileo will have similar limitations until the entire constellation is in orbit.