The X-Price vehicles itself will not compete with orbital launch vehicles. But they are a good way to learn how to build a real reusable space vehicle instead of just converted ICBMs like we have been doing for the last 50 years.
And there is a commercial rocket in production that is small compared to its competitors and has a reusable first stage. It will be used to launch satellites for the DOD, among others.
There are already plans to scale this vehicle up to a much larger size. And the first stage will still be reusable.
There is no official information on the scaled site yet. But there are many people in mojave who are very interested in space, and launching a spacecraft is not exactly something you can hide that easily.
So probably there was a guy with a telescope and a stopwatch watching this. From the data it is quite easy to estimate altitude and velocity. We will get much better and more accurate data from scaled soon.
There is a very logical upgrade path from a suborbital to an orbital vehicle.
A manned suborbital vehicle going to 100km altitude needs a reaction control system to orient itself in a vacuum. It needs to be pressurized. And it needs a (small) heat shield.
So it really is a space craft that just does not have enough delta-v to make orbit.
By increasing the available delta-v incrementally you can work out the bugs much easier than if you had to do it all in one big step like they did with the shuttle.
A suborbital craft is also very interesting as a reusable first stage for a microsattelite launch vehicle. For example with the payload of the spaceship one and an expendable upper stage it should be possible to get about 10kg into low earth orbit. This would be very interesting for universities and radio amateurs that can not affor d a large launch vehicle.
The DOD has also shown some interest in microsattelites. This is a nice way to make some money while developing a real reusable orbital space craft.
The second stage is quite cool in other aspects too:
-It does not use liquid hydrogen, so the propellants can be stored for a few weeks.
-It uses heated helium for propellant settling and gimballing and dual redundant torch igniters for ignition, so it can be restarted basically indefinitely as long as there is some propellant left.
-As a pressure fed stage it is extremely rugged, so the empty stage could be reused as the hull of a space station. That would make most sense for the falcon V, since the falcon I upper stage is not big enough.
You are right of course. But what makes you think that spacex has not thought of that? They produce a large part of the vehicle inhouse for that very reason.
It is not exactly mass production, since there are just not enough customers. But they make an effort to minimize manual labor.
Falcon I and Falcon V would be a bit too small to be useful for SPS. But the long term planning of Elon Musk is to build a real heavy lifter (Saturn V class). That would make it possible to build solar power satellites and really open up the space frontier.
Lets just hope the first launch goes according to plan. That would be really good for attracting outside investors.
For the payloads of today, you are right. But first of all, falcon I and especially falcon V is designed to be extremely reliable. Simple technology has a tendency to just work once it is debugged. Just ask the russians.
And second, the main reason satellites are so expensive is that they have to use very exotic materials and low margins to save mass. If you have a cheaper launcher you can build your satellite heavier, cheaper and more rugged.
Nasa has a habit of having so much paperwork and specification stuff that only the big launch companies (boeing and lockmart) need apply. They also have a habit of being heavily biased against new companies.
The DOD on the other hand seems to be really interested in cheap, reliable and fast launch. They want to be able to put up a sattelite on short notice, and none of the incumbent companies are able to provide this.
That is why the DOD has bought the first launch of the Falcon I and will buy many launches on Falcon V. Of course the high value payloads will go up on Atlas V for the forseeable future, but there will be a lot of pressure on boeing and lockmart if falcon is successful.
The falcon first stage, which represents the bulk of the mass of the vehicle, is designed to be reusable. It will deploy a parachute, land in the ocean and be recovered. The only expendable part in the first stage is the nozzle.
They have also developed their own turbopump and reusable engine with quite impressive performance.
And all that for less than 100 million $. For that kind of money, NASA could probably produce a really nice paper study, but nothing that gets off the ground.
Do you have any plans to add BeOS style live queries to ReiserFS? They were IMHO the best feature of the BeOS, and they are the only thing I really miss when using linux. Could this be done as a plugin, or does it require more fundamental changes?
I know that linux has the dnotify mechanism, but that is only useful for watching for changes in a single directory, so it is basically useless for most purposes.
"Without seeing (in the Java source code) how the templates are implemented I can't say that I agree or disagree with your statement that they will be inefficient, though I'm inclined to disagree based on your example."
Slashcode swallowed some brackets even though I was in text mode:-(
What I mean is the following: If you create for example an ArrayList of ints, the most efficient way to store these ints internally would obviously be an int[] and not an Object[]. But even though java uses templates, it still stores primitive types such as int in an Object[], so there is a huge temporary object creation overhead. Whenever you store an int in your IntArrayList, a new Integer object is created on the heap and an old Integer object has to be garbage collected. In.NET you just store a 32bit value in an array, which is a single operation on most processors.
The.NET templates will create a different class for each primitive type, so that primitive types will indeed be stored in their corresponding primitive arrays without creating objects on the heap. For classes, the.NET implementation behaves similar to the java implementation: There is only one internal class created for all reference types.
"Templates or not, objects are going to be stored the same way. The difference is how those objects are retrieved. Right now you have to cast everything coming out of an ArrayList (unless the Object reference is sufficient)...not only is that being moved to the language but you also gain compile-time type checking. That will only serve to reduce errors and make the software more reliable. Templates are optional anyway - you don't have to use them. I'm looking forward to them."
Me too. It is not that I dislike the new features. I just think that they could have been implemented better, faster and earlier.
"I don't think you're ever going to see VM sharing. If applications can share VMs then one rogue app could bring down other apps by trashing the VM (never supposed to happen) or by poor thread management."
VM sharing does not mean that all java programs must run in one process. But for most desktop applications this would make a lot of sense. You are right about the thread management, but you could always restrict the number of threads an application can create. Just have a nice XML file which describes how much resources each application may allocate. That is the way.NET does it, by the way.
If sun will not do VM sharing, you will never see decent client applications written in java. Just think about it: for each java application you start, the whole swing library has to be JIT-Compiled anew. What a huge waste of processing power!
For years java zealots have told us that features like automatic boxing and templates are dangerous because they hide what really happens.
Now that java has them too, they are suddenly the biggest thing since sliced bread. Most modern languages have had automatic boxing for ages, and never made a big deal about it.
And about the new templates: they are just syntactic sugar. For example if you have an ArrayList, the elements will still be stored on the heap as Integer objects. That is very inefficient.
And what about VM sharing? Will it be in java 1.5, or will we still have to wait 30 seconds for java programs to start up?
Re:It is all by design...
on
Hijacking .NET
·
· Score: 1
Mod this up!
This has to be the most stupid slashdot posting I ever saw. There is a mechanism in place so that only fully trusted code can use private members, but still you get the impression that this is some kind of huge security hole.
Maybe some people should try think before they embarass themselves.
Why do you think that it is "rather unlikely" that freedom of speech will be seriously impaired in western nations? In Nordrhein-Westfalen, a state in germany, several sites such as Stormfront.org and also rotten.com are blocked at the DNS and router level. Sites like Indymedia will be next, because they have open posting and therefore occasionally post illegal material.
There is most definitely a need for an anonymous and decentralized information exchange system even in western "democracies".
Why don't you do the same if you care about free speech? Freenet is already used by the chinese opposition. Some european countries like france, greece and germany already censor the internet, so freenet is also important for western "democracies".
Some day soon something like freenet will be nessecary even in the US if you want to say something critical about bush or ashcroft without getting on some list of potential terrorists.
There is absolutely nothing wrong with the music industry trying to invent a good watermarking technology. As long as they fight illegal copies with technical means i am all for it.
The problem starts when they buy legislation instead of using technology to protect their stuff. My problem with mandatory DRM is *not* that I can no longer get britney spears songs for free, but that I am no longer allowed to own a general purpose computer.
This is a really nice project. But it only makes sense if it is combined with agriculture or other forms of solar power generation.
The carnot efficiency is defined as e=(T1-T0)/T1. If we assume T1=20C=293K, T0=0C=273K, the maximum thermodynamic efficiency is 20/293=0.068=7%. And this is the theoretical maximum. So it would be more reasonable to expect something like 4% for the total efficiency.
On the plus side, this design comes with built-in energy storage for the night, it can be used for agriculture, and it might be possible to increase its efficiency by placing photovoltaic cells in the collector area.
If you consider that this thing will be a huge tourist attraction, building it will definitely be worth it.
Its most definitely a brilliant idea. It is impossible to build a drilling rig that drills a 30m deep hole into a comet with 500kg, let alone all the equipment for decelerating from 6km/s and a soft landing.
A 500kg copper ball on the other hand is cheap as dirt to build and can not break like other fragile nasa equipment (remember mars polar lander?). And contrary to popular belief, by far the most expensive part of a scientific mission is building the probe, not launching it (Scientific probes are not buildt in series).
So I think that this mission is a remarkably good idea. Maybe NASA should build these things in series: Wanna find out if there is water on the mars or some moon? Just blow a hole into its surface and measure the composition of the output plume.
And for all those wackos that think that blowing a hole into a comet or whatever is immoral: The solar system is huge, there are millions of comets, asteroids etc. and each and every one of them is capable of destroying civilisation as we know it. So finding out stuff about their density, structural strength and composition is vital if humankind wants to survive. Still not convinced? Better commit suicide right now!
Hello everybody, and thanks to Linus and all the other kernel hackers for this marvelous piece of software called linux 2.4.
Please do yourself a favor and compile the kernel with HZ=1024 instead of HZ=100 (this is the frequency for multitasking timeslices).
This gives you a much better "perceived performance" especially for gui applications.
The drawback is that since the machine switches the execution context more often, performance goes down a bit. But on my machine (K6-II 350MHz, 196MB) it is less than one percent, so it does not matter at all as long as you do not do serious number crunching.
If you compile with a very strange value like 4096 Hz (yes, I tried that too:-), ps and top get irritated but everything else works just fine. In fact, I write this post at 4096! Proof:
With 1024 even ps and top do work, since this frequency is used by the alpha port. And your KDE/Gnome/whatever will feel much better even with the current scheduler.
Sorry if this is redundant, but I think it is important,
Slashdot Mirror
There are some images on RLV News . And there is also a story on space.com. Everybody in mojave must have seen and heard this.
The X-Price vehicles itself will not compete with orbital launch vehicles. But they are a good way to learn how to build a real reusable space vehicle instead of just converted ICBMs like we have been doing for the last 50 years.
And there is a commercial rocket in production that is small compared to its competitors and has a reusable first stage. It will be used to launch satellites for the DOD, among others.
There are already plans to scale this vehicle up to a much larger size. And the first stage will still be reusable.
There is no official information on the scaled site yet. But there are many people in mojave who are very interested in space, and launching a spacecraft is not exactly something you can hide that easily.
So probably there was a guy with a telescope and a stopwatch watching this. From the data it is quite easy to estimate altitude and velocity. We will get much better and more accurate data from scaled soon.
There is a very logical upgrade path from a suborbital to an orbital vehicle.
A manned suborbital vehicle going to 100km altitude needs a reaction control system to orient itself in a vacuum. It needs to be pressurized. And it needs a (small) heat shield.
So it really is a space craft that just does not have enough delta-v to make orbit.
By increasing the available delta-v incrementally you can work out the bugs much easier than if you had to do it all in one big step like they did with the shuttle.
A suborbital craft is also very interesting as a reusable first stage for a microsattelite launch vehicle. For example with the payload of the spaceship one and an expendable upper stage it should be possible to get about 10kg into low earth orbit. This would be very interesting for universities and radio amateurs that can not affor d a large launch vehicle.
The DOD has also shown some interest in microsattelites. This is a nice way to make some money while developing a real reusable orbital space craft.
Many launchers have common bulkheads. Most notably the Saturn V. There was never any problem with that.
So I think your fears are unfounded.
The second stage is quite cool in other aspects too:
-It does not use liquid hydrogen, so the propellants can be stored for a few weeks.
-It uses heated helium for propellant settling and gimballing and dual redundant torch igniters for ignition, so it can be restarted basically indefinitely as long as there is some propellant left.
-As a pressure fed stage it is extremely rugged, so the empty stage could be reused as the hull of a space station. That would make most sense for the falcon V, since the falcon I upper stage is not big enough.
You are right of course. But what makes you think that spacex has not thought of that? They produce a large part of the vehicle inhouse for that very reason.
It is not exactly mass production, since there are just not enough customers. But they make an effort to minimize manual labor.
Falcon I and Falcon V would be a bit too small to be useful for SPS. But the long term planning of Elon Musk is to build a real heavy lifter (Saturn V class). That would make it possible to build solar power satellites and really open up the space frontier.
Lets just hope the first launch goes according to plan. That would be really good for attracting outside investors.
I read the sci.space newsgroups regularly as well as the very good hobbyspace site, and I have heard nothing about this.
Could you elaborate? Or are you just spreading FUD?
For the payloads of today, you are right. But first of all, falcon I and especially falcon V is designed to be extremely reliable. Simple technology has a tendency to just work once it is debugged. Just ask the russians.
And second, the main reason satellites are so expensive is that they have to use very exotic materials and low margins to save mass. If you have a cheaper launcher you can build your satellite heavier, cheaper and more rugged.
Nasa has a habit of having so much paperwork and specification stuff that only the big launch companies (boeing and lockmart) need apply. They also have a habit of being heavily biased against new companies.
The DOD on the other hand seems to be really interested in cheap, reliable and fast launch. They want to be able to put up a sattelite on short notice, and none of the incumbent companies are able to provide this.
That is why the DOD has bought the first launch of the Falcon I and will buy many launches on Falcon V. Of course the high value payloads will go up on Atlas V for the forseeable future, but there will be a lot of pressure on boeing and lockmart if falcon is successful.
Isn't competition great?
The falcon first stage, which represents the bulk of the mass of the vehicle, is designed to be reusable. It will deploy a parachute, land in the ocean and be recovered. The only expendable part in the first stage is the nozzle.
They have also developed their own turbopump and reusable engine with quite impressive performance.
And all that for less than 100 million $. For that kind of money, NASA could probably produce a really nice paper study, but nothing that gets off the ground.
Do you have any plans to add BeOS style live queries to ReiserFS? They were IMHO the best feature of the BeOS, and they are the only thing I really miss when using linux. Could this be done as a plugin, or does it require more fundamental changes?
I know that linux has the dnotify mechanism, but that is only useful for watching for changes in a single directory, so it is basically useless for most purposes.
"Without seeing (in the Java source code) how the templates are implemented I can't say that I agree or disagree with your statement that they will be inefficient, though I'm inclined to disagree based on your example."
:-(
.NET you just store a 32bit value in an array, which is a single operation on most processors.
.NET templates will create a different class for each primitive type, so that primitive types will indeed be stored in their corresponding primitive arrays without creating objects on the heap. For classes, the .NET implementation behaves similar to the java implementation: There is only one internal class created for all reference types.
.NET does it, by the way.
Slashcode swallowed some brackets even though I was in text mode
What I mean is the following: If you create for example an ArrayList of ints, the most efficient way to store these ints internally would obviously be an int[] and not an Object[]. But even though java uses templates, it still stores primitive types such as int in an Object[], so there is a huge temporary object creation overhead. Whenever you store an int in your IntArrayList, a new Integer object is created on the heap and an old Integer object has to be garbage collected. In
The
"Templates or not, objects are going to be stored the same way. The difference is how those objects are retrieved. Right now you have to cast everything coming out of an ArrayList (unless the Object reference is sufficient)...not only is that being moved to the language but you also gain compile-time type checking. That will only serve to reduce errors and make the software more reliable. Templates are optional anyway - you don't have to use them. I'm looking forward to them."
Me too. It is not that I dislike the new features. I just think that they could have been implemented better, faster and earlier.
"I don't think you're ever going to see VM sharing. If applications can share VMs then one rogue app could bring down other apps by trashing the VM (never supposed to happen) or by poor thread management."
VM sharing does not mean that all java programs must run in one process. But for most desktop applications this would make a lot of sense. You are right about the thread management, but you could always restrict the number of threads an application can create. Just have a nice XML file which describes how much resources each application may allocate. That is the way
If sun will not do VM sharing, you will never see decent client applications written in java. Just think about it: for each java application you start, the whole swing library has to be JIT-Compiled anew. What a huge waste of processing power!
For years java zealots have told us that features like automatic boxing and templates are dangerous because they hide what really happens.
Now that java has them too, they are suddenly the biggest thing since sliced bread. Most modern languages have had automatic boxing for ages, and never made a big deal about it.
And about the new templates: they are just syntactic sugar. For example if you have an ArrayList, the elements will still be stored on the heap as Integer objects. That is very inefficient.
And what about VM sharing? Will it be in java 1.5, or will we still have to wait 30 seconds for java programs to start up?
Mod this up!
This has to be the most stupid slashdot posting I ever saw. There is a mechanism in place so that only fully trusted code can use private members, but still you get the impression that this is some kind of huge security hole.
Maybe some people should try think before they embarass themselves.
Why do you think that it is "rather unlikely" that freedom of speech will be seriously impaired in western nations? In Nordrhein-Westfalen, a state in germany, several sites such as Stormfront.org and also rotten.com are blocked at the DNS and router level. Sites like Indymedia will be next, because they have open posting and therefore occasionally post illegal material.
There is most definitely a need for an anonymous and decentralized information exchange system even in western "democracies".
Why don't you do the same if you care about free speech? Freenet is already used by the chinese opposition. Some european countries like france, greece and germany already censor the internet, so freenet is also important for western "democracies".
Some day soon something like freenet will be nessecary even in the US if you want to say something critical about bush or ashcroft without getting on some list of potential terrorists.
regards,
mrright
Exactly!
There is absolutely nothing wrong with the music industry trying to invent a good watermarking technology. As long as they fight illegal copies with technical means i am all for it.
The problem starts when they buy legislation instead of using technology to protect their stuff. My problem with mandatory DRM is *not* that I can no longer get britney spears songs for free, but that I am no longer allowed to own a general purpose computer.
This is a really nice project. But it only makes sense if it is combined with agriculture or other forms of solar power generation.
The carnot efficiency is defined as e=(T1-T0)/T1. If we assume T1=20C=293K, T0=0C=273K, the maximum thermodynamic efficiency is 20/293=0.068=7%. And this is the theoretical maximum. So it would be more reasonable to expect something like 4% for the total efficiency.
On the plus side, this design comes with built-in energy storage for the night, it can be used for agriculture, and it might be possible to increase its efficiency by placing photovoltaic cells in the collector area.
If you consider that this thing will be a huge tourist attraction, building it will definitely be worth it.
Its most definitely a brilliant idea. It is impossible to build a drilling rig that drills a 30m deep hole into a comet with 500kg, let alone all the equipment for decelerating from 6km/s and a soft landing.
A 500kg copper ball on the other hand is cheap as dirt to build and can not break like other fragile nasa equipment (remember mars polar lander?). And contrary to popular belief, by far the most expensive part of a scientific mission is building the probe, not launching it (Scientific probes are not buildt in series).
So I think that this mission is a remarkably good idea. Maybe NASA should build these things in series: Wanna find out if there is water on the mars or some moon? Just blow a hole into its surface and measure the composition of the output plume.
And for all those wackos that think that blowing a hole into a comet or whatever is immoral: The solar system is huge, there are millions of comets, asteroids etc. and each and every one of them is capable of destroying civilisation as we know it. So finding out stuff about their density, structural strength and composition is vital if humankind wants to survive. Still not convinced? Better commit suicide right now!
greetings,
MrRight
Hello everybody, and thanks to Linus and all the other kernel hackers for this marvelous piece of software called linux 2.4.
:-), ps and top get irritated but everything else works just fine. In fact, I write this post at 4096! Proof:
Cool java games? Try www.gamemakers.de
Please do yourself a favor and compile the kernel with HZ=1024 instead of HZ=100 (this is the frequency for multitasking timeslices).
This gives you a much better "perceived performance" especially for gui applications.
The drawback is that since the machine switches the execution context more often, performance goes down a bit. But on my machine (K6-II 350MHz, 196MB) it is less than one percent, so it does not matter at all as long as you do not do serious number crunching.
If you compile with a very strange value like 4096 Hz (yes, I tried that too
ps
Unknown HZ value! (4096) Assume 100.
PID TTY TIME CMD
862 pts/0 00:00:01 cat
882 pts/1 00:00:04 bash
893 pts/1 00:00:02 wvdial
1035 pts/2 00:00:04 bash
1042 pts/2 00:00:04 ps
With 1024 even ps and top do work, since this frequency is used by the alpha port. And your KDE/Gnome/whatever will feel much better even with the current scheduler.
Sorry if this is redundant, but I think it is important,
MrRight
________________________________________________