OK, so am I the only one surprised at this, and given their HUGE market share, who in their right mind would want one?
Not only that, the Fujitsu-Siemens joint venture is reportedly breaking apart. What that means for the future of FS laptops remains to be seen. I for one would be wary of that kind of deal.
OK, I'm dating (and placing) myself with this one...
But I honestly think that no list of error messages should omit the scourge of ZX Spectrum users. Ah, the joys of fiddling with volume, treble and head alignment.
Too bad most of the satellites will be knocked out of orbit by all the debris their last little stunt in orbit left behind. Most unlikely, since most of the satellites will use the medium Earth orbit, probably ~20000 km, which is far, far above the debris field left by the ASAT shootdown. The rest of the satellites will be geostationary (per TFA), still farther away.
Original HP pocket calculators used bubble memory.
Um, no. The HP 9100A used core memory (both parts of ROM and all of RAM), but that was a honking big desktop machine. All pocket calculators used PMOS RAM until the appearance of "continuous memory" (CMOS) models.
Sure there's toxic side by-products, but who's not to say that plutonium can't be used in something else?
Oh wait it can,
radioisotope thermoelectric generators (think long lived spaceprobes)
That Plutonium isotope (Pu-238) is obtained by irradiation of Np-237, itself a reactor-produced isotope which has to be chemically separated from other nuclear waste. All of which makes Pu-238 horrendously expensive. Just FYI.
While I'm not managing more than a couple of/22s, that's still a lot of subnets, as we're mainly doling out/29 and/28 blocks. I've had all of parent's issues (minus router memory, so far), and I'm still doing fine with a spreadsheet.
Unallocated subnets have a light yellow background.
The leftmost column (dark gray boxes) tracks/28s, and the second column (light gray) tracks/27s.
So, if a box occupies a single row, the corresponding allocation is of that size (cf. 160/27, 192/27 and 224/28.) If it spans multiple rows, the allocation is subdivided. With a little practice, it's quite obvious if there's a free subnet, what size it is, how easy would it be to expand etc.
The inflatable spacecraft idea has been floated (heh) in the 80s by a scientist at LLNL who previously came up with the idea of using gobs of small interceptors for strategic missile defense -- the concept known as Brilliant Pebbles. His rather aggressive promotion of inflatables attracted a lot of criticism, and someone called the scheme "Brilliant Condoms". With a moniker like that, it's no wonder that support and funds have been scarce.
The idea has its merits, as mentioned elsewhere in the comments... Volume to mass ratio is much better than that of a solid structure, and micrometeorite shielding can be provided adequately.
Unless we're talking about a shuttle engine that I'm not familiar with, the three main shuttle engines do burn in the air.
They are ignited on the ground, and ignition depends on ground infrastructure. In-flight ignition would require engine modifications, and that is why the J-2 is an attractive alternative -- while its performance is lower, the engine is far simpler and specifically designed for in-flight startup.
You might enineer it well enough to measure a wobble of the earth, but to actually package it so it can survive 10.000 years and still have a meaning is not only an engineering feat, it must be an antropology feat as well, to make people long after this understand what it is and leave it in pieces.
The last part of that sentence indeed summarizes the chief obstacle to longevity of any monument.
Incidentally, this is not the first time that such a time-scale has been deliberately studied. A while ago the U.S. Dept. of Energy actually commissioned a study into the problem of marking a long-term nuclear waste repository (WIPP in New Mexico, Yucca Mountain if it ever opens) so as to prevent unintentional intrusion and possible spread of contamination.
Physicist and SF author Gregory Benford was on the team, and his account appears as the first chapter of his book, Deep Time. The book is, it seems, out of print, but still available on Amazon. There is a slightly garbled copy of that chapter online, minus the cool illustrations of several marker concepts. Some illustrations appear in the excerpted report of the WIPP Marker Panel. Fascinating and slightly unsettling stuff.
You mentioned Burt Rutan's works as an example for NASA to follow. Well, First off, Burt did not go high. He went 60 miles. Well, now he needs to go to 300 miles. My understanding is that it gets exponentially harder as you go higher.
He went high, but not fast. Shooting payload 300 miles up isn't too difficult. What is harder (truly exponentially harder, due to the rocket equation) is reaching orbital velocity.
...many designers are looking to using ramjets or oxygen-breathing rockets, as that reduces the fuel you need.
Air-breathing launch assist engines are of dubious practicability, for several reasons. First, you cannot start a ramjet engine from standstill: it has to be accelerated to at least half the speed of sound, preferably more. Second, a ramjet peters out at about Mach 5-7, after which (if you still want to air-breathe) you must use a scramjet (supersonic combustion ramjet). Finally, you'll need rocket engines anyway, since it's difficult to air-breathe in vacuum;)
So you need at least two sets of engines (air-breathing + rocket), plus the means of accelerating the craft until the first set works. You might as well use the rockets all the way.
Complexity aside, you really want to spend as little time as possible within the atmosphere, to reduce drag losses, further limiting the utility of air-breathing.
There are viable air-breathing designs, such as Skylon/SABRE. But that one is not your regular (sc)ramjet -- look it up to see why. In the words of Alan Bond, the designer of the concept, "I began with a good rocket engine and made it a bad air-breather. Everybody previously had done the reverse."
at least Reagan got this point right: make them _think_ you're crazy enough to use the bomb, without actually _saying_ you're going to use it
Well, he had a worthy predecessor: Nixon and his belief in the Madman Theory of foreign policy. Not that it really worked when tried out. For a fascinating write-up, see this article.
25 metric tons...does this mean we are one step closer to start launching our garbage into the sun?
Launching into the Sun is energetically wasteful; the needed delta-v is about 30 km/s, as opposed to 16 km/s or so for the Solar escape trajectory, i.e., leaving the Solar system forever. There are even less demanding and arguably better destinations, see this discussion for the list of possibilites.
(The assumed "garbage" is concentrated, long-lived radioactive waste; the feasibility of launching other types of waste is questionable.)
Slashdot Mirror
OK, so am I the only one surprised at this, and given their HUGE market share, who in their right mind would want one?
Not only that, the Fujitsu-Siemens joint venture is reportedly breaking apart. What that means for the future of FS laptops remains to be seen. I for one would be wary of that kind of deal.
OK, I'm dating (and placing) myself with this one... But I honestly think that no list of error messages should omit the scourge of ZX Spectrum users. Ah, the joys of fiddling with volume, treble and head alignment.
Cisco IOS will route IPv6, but it does doesn't do it in hardware
Sup720 + PFC3 + DFC3 routes IPv6 in hardware. It's not exactly new.
Original HP pocket calculators used bubble memory.
Um, no. The HP 9100A used core memory (both parts of ROM and all of RAM), but that was a honking big desktop machine. All pocket calculators used PMOS RAM until the appearance of "continuous memory" (CMOS) models.
So who's IAN
That would be me...
and why does he 'heart' AL?
Beats me.
Sure there's toxic side by-products, but who's not to say that plutonium can't be used in something else?
That Plutonium isotope (Pu-238) is obtained by irradiation of Np-237, itself a reactor-produced isotope which has to be chemically separated from other nuclear waste. All of which makes Pu-238 horrendously expensive. Just FYI.Oh wait it can,
radioisotope thermoelectric generators (think long lived spaceprobes)
While I'm not managing more than a couple of /22s, that's still a lot of subnets, as we're mainly doling out /29 and /28 blocks. I've had all of parent's issues (minus router memory, so far), and I'm still doing fine with a spreadsheet.
What's the trick? Visualisation. Look at the image:
So, if a box occupies a single row, the corresponding allocation is of that size (cf. 160/27, 192/27 and 224/28.) If it spans multiple rows, the allocation is subdivided. With a little practice, it's quite obvious if there's a free subnet, what size it is, how easy would it be to expand etc.
Actually, just yesterday I was praying for VI key bindings for eclipse.
There is a quite decent vi plugin for Eclipse (payware, but worth it if you don't want to fight your muscle memory.)
correction:
en
conf t
int fa0/15
shut
exit
do wr
... they were already using portable translators of a kind?
The inflatable spacecraft idea has been floated (heh) in the 80s by a scientist at LLNL who previously came up with the idea of using gobs of small interceptors for strategic missile defense -- the concept known as Brilliant Pebbles. His rather aggressive promotion of inflatables attracted a lot of criticism, and someone called the scheme "Brilliant Condoms". With a moniker like that, it's no wonder that support and funds have been scarce.
The idea has its merits, as mentioned elsewhere in the comments... Volume to mass ratio is much better than that of a solid structure, and micrometeorite shielding can be provided adequately.
They are ignited on the ground, and ignition depends on ground infrastructure. In-flight ignition would require engine modifications, and that is why the J-2 is an attractive alternative -- while its performance is lower, the engine is far simpler and specifically designed for in-flight startup.
The last part of that sentence indeed summarizes the chief obstacle to longevity of any monument.
Incidentally, this is not the first time that such a time-scale has been deliberately studied. A while ago the U.S. Dept. of Energy actually commissioned a study into the problem of marking a long-term nuclear waste repository (WIPP in New Mexico, Yucca Mountain if it ever opens) so as to prevent unintentional intrusion and possible spread of contamination.
Physicist and SF author Gregory Benford was on the team, and his account appears as the first chapter of his book, Deep Time. The book is, it seems, out of print, but still available on Amazon. There is a slightly garbled copy of that chapter online, minus the cool illustrations of several marker concepts. Some illustrations appear in the excerpted report of the WIPP Marker Panel. Fascinating and slightly unsettling stuff.
He went high, but not fast. Shooting payload 300 miles up isn't too difficult. What is harder (truly exponentially harder, due to the rocket equation) is reaching orbital velocity.
Air-breathing launch assist engines are of dubious practicability, for several reasons. First, you cannot start a ramjet engine from standstill: it has to be accelerated to at least half the speed of sound, preferably more. Second, a ramjet peters out at about Mach 5-7, after which (if you still want to air-breathe) you must use a scramjet (supersonic combustion ramjet). Finally, you'll need rocket engines anyway, since it's difficult to air-breathe in vacuum ;)
So you need at least two sets of engines (air-breathing + rocket), plus the means of accelerating the craft until the first set works. You might as well use the rockets all the way.
Complexity aside, you really want to spend as little time as possible within the atmosphere, to reduce drag losses, further limiting the utility of air-breathing.
There are viable air-breathing designs, such as Skylon/SABRE. But that one is not your regular (sc)ramjet -- look it up to see why. In the words of Alan Bond, the designer of the concept, "I began with a good rocket engine and made it a bad air-breather. Everybody previously had done the reverse."
Well, he had a worthy predecessor: Nixon and his belief in the Madman Theory of foreign policy. Not that it really worked when tried out. For a fascinating write-up, see this article.
Launching into the Sun is energetically wasteful; the needed delta-v is about 30 km/s, as opposed to 16 km/s or so for the Solar escape trajectory, i.e., leaving the Solar system forever. There are even less demanding and arguably better destinations, see this discussion for the list of possibilites.
(The assumed "garbage" is concentrated, long-lived radioactive waste; the feasibility of launching other types of waste is questionable.)