I am not well versed in regenerative biology, but my girlfriend happens to be getting her PhD in that field. I sent her this link for comment and here's what she said:
From article: "The wounded Marine's recovery is particularly exciting for scientists as it involves the regeneration of skeletal muscle which ordinarily does not grow back"
From any book in any regenerative scientist's library: "It has been known for more than a century that skeletal muscle, the most abundant tissue of the body, has the ability to regenerate new muscle fibers after it has been damaged by injury or as a consequence of diseases such as muscular dystrophy (1)"
(in this case the reference = Carlson BM. The regeneration of skeletal muscle. A review. Am J Anat. 1973;137(2):119–149. View this article via: PubMed CrossRef)
Annoying! Maybe he is on to something that really does help quicken the natural regeneration response or promotes better healing or something, but no one will ever know because there are no controls. He has no mouse controls... he obviously can't do human controls and people are just slapping this stuff on there because... "at least it doesn't hinder the response". (but he could be charging billions for a placebo!)
Oh well. Science is stupid. The media is even dumber.
In other words: Slashdot, please stop posting articles from the Daily Mail. Also, on background, I know the doctor mentioned in the article, Badylak, was kicked out of his group for poor research practices that included trial by media instead of peer review. This sort of publicity piece is his MO.
They don't test shuttle tanks in Mississippi. They could have tested in Florida and in fact did do some testing for a 240" solid booster in south Florida and they test Centaurs in West Palm to this day. The large space? They where building the VAB so building a production building in Florida would have been simple. There is a good reason for it to be Louisiana instead of say AZ. But the reason that it wasn't in Florida was to spread the "wealth" around. In many ways it isn't a bad idea if you look at maximizing the economic benefits or a program. But if you look at just the cost it adds up. That is one of the good things about a lot of big government programs like that. Yes they cost a lot of tax dollars but a good amount of that money gets recycled from the jobs that it creates. You also have the RnD benefit as well. I am not even saying that this is the worst or best way to do these projects. Just that is the way they are done.
Actually, they DID test the space shuttle tanks in Mississippi. See here: http://en.wikipedia.org/wiki/MPTA-ET. They don't test every tank there, but they tested the early ones and they test tanks that have certain kinds of problems, such as leaks.
As for building the tanks in Florida, the Kennedy VAB in Florida is 8 acres. The Michoud facility in New Orleans is vastly larger: more than 43 acres. Saying "because they built the VAB in Florida they could have built a manufacturing facility for large scale boosters" shows little knowledge of how the tanks are produced and how much space it takes to produce them. There was an existing 43 acre facility laid out to produce large scale industrial products in LA that the government already owned. The only additional cost of putting production there was barge traffic to Mississippi/Florida. Compare that to the cost of building a new 43-acre environmentally controlled facility from scratch in Florida, and I don't think that's a trivial decision. You can convince me, but you haven't thus far.
I'll freely admit that most of the Michoud space is not currently used. Original production plans were to produce one or two tanks per month, which grossly overestimated the Space Shuttle's turnaround efficiency. In the end, much of the Michoud capacity was not needed. But if you want to make the argument that Michoud was selected wholly or even primarily as a political favor, you have more homework to do.
I can't speak to the other cases, but they built the first stage of the Saturn V in Louisiana because...
1. They needed a very large industrial space. The factory is a converted aircraft production facility built during WWII.
2. They needed deep water access to ship the giant vehicles. External Tanks and the Saturn S-IC cannot be shipped by road or rail.
3. The selection was tied to accessibility of both Kennedy Space Center in Florida (for launching) and Stennis Space Center in Mississippi (for testing). Once you start to pick a few locations, logistics become non-trivial and your next choice becomes more constrained.
I can't assure you that graft had nothing to do with it (can you assure me that any part of any government program in history didn't have some back-deal component?), but the locations were not selected purely for political effect.
I totally agree; I too was left very concerned after reading his thoughtful and thorough analysis. And I'm really disappointed that (practically) no one on Slashdot took a look at it. Especially after reading his analysis of confirmation bias and so on, the knee-jerk responses on this thread are particularly disheartening.
The law review article upon which the linked story is written is 80 pages long. It is, as best I can tell, totally consistent with known science (it doesn't postulate "black holes destroying the universe" or any such nonsense). It is an attempt to do 3 things:
1. Ask how a court ought to address a science experiment that could, by some very unlikely chance, destroy the earth. He uses LHC as an example, but also suggests Strong AI and nanotechnology as possible future examples.
2. Analyze how a non-expert court can, or should, evaluate highly technical and possibly controversial scientific claims for and against the safety of a bleeding-edge research project.
3. Analyze how logical or cognitive errors could realistically lead a scientist to accidentally or intentionally understate or mischaracterize the risks of her research.
Anyone on this board droning on about "Shut-up-the-LHC-can't-destroy-the-world" either DRTFA or totally misunderstood it. I will now quote the author:
My motivation in writing is certainly not to engender fear. I have no apprehension to share...
It is part of our 21st Century reality that we must take seriously a number of surreal planetary disaster scenarios. In that sense, the synthetic-black-hole disaster is not unique. For some time now, we have been confronted with the possibility of nuclear war and global climate change. In the future, we may have to remove still more scenarios from the science fiction category and place them on a list of real worries. Someday, we may need to seriously consider catastrophic threats from nanotechnology, genetic engineering, or artificial intelligence. Each one of these human-made global disaster scenarios involves incredibly complex questions of science, engineering, and mathematics. Courts must develop tools to deal meaningfully with such complexity. Otherwise, the wildly expanding sphere of human knowledge will overwhelm the institution of the courts and undo the rule of law—just when we need it most.
If he had chosen anthropogenic global climate change as his topic of analysis, I think there would have been a more interesting debate on Slashdot, but apparently any mention of "LHC" in the same breath as "black hole" causes some sort of hysterical allergic reaction in some people.
They still are broadcast! Well, on basic cable anyway. I get to work launch support for the External Tank from here in New Orleans (which is kind of like sitting at the kiddie table of the "real" launch support at Johnson Space Center), and we actually watch the launch on live TV, along with our official NASA video feed. Sometimes the TV version is more informative, frankly.
You're right that LOX isn't as cold as some of its cryo kin, but it's so damn heavy and reactive that I would still argue that using it would be beyond anything this designer seems to be accounting for. Even loading it is a problem, because it gassifies and takes time to reach optimal density, hence the replenish loading cycles on most LOX systems. And remember also that the author claimed he could launch without substantial ground support.
No requirement for fixed launch facilities -- The space plane can operate from a conventional runway without any requirements of ground launch facilities.
No ground support, but you want to use cryogenic propellants? I mean, this guy is delusional! (The author, not you).
Scaled Composites did their best to build a composite tank that could safely and repeatedly handle N2O, which should be a better-behaved oxidizer, and they still managed to blow one up and kill a few technicians. A different system, of course, but if you read the article, it just seemed like the author was completely insane about the difficulty of pulling this stuff off.
As to the nozzle savings, I used to have a chart that explained the penalty a nozzle suffers in thrust due to over-expansion at sea level and under-expansion in the upper atmosphere, but I can't find it. Maybe you can correct me; I don't think the savings gained by starting the engine at altitude would be tremendous unless you could tow to above 30,000 ft, when using a large area ratio becomes really advantageous. Could the tow vehicle get you that high? Remember, you're carrying an awful lot of heavy propellant. And remember also that the author promised development costs of $4 million, total! I think you'd need a heck of a tow vehicle, one that would cost well north of $4M.
Anyway, thanks for elevating this conversation with some really great examples, putting the necessary Isp in perspective.
Manned space flight will have to be demanding and precise no matter who does it. You're right that the "difficult" part may have more to do with NASA than anything.
Otherwise, I totally agree. The shuttle was deeply flawed, and NASA is a deeply dysfunctional organization. But for all its flaws, the shuttle is real and not imaginary.
Of course, the shuttle has cost real dollars and real lives, whereas this fellow's fantasy ship hasn't hurt anyone and probably never will (because nobody would fund it). So I guess to be morally consistent, I would be better off directing my ire at NASA.
But there's a certain arrogance and laziness in the posted article. It's like it can't even be bothered to pretend to be a real spaceship.
One can argue that, for all its flaws, the shuttle was an earnest attempt at creating a revolutionary space architecture. One doomed by bureaucracy, politics, mission creep, economics and technological deficiencies, perhaps, but REAL.
I'm all for privatization of space, and part of privatization is criticizing the hell out of weak proposals. Part of it is getting a little angry at inferior products and ideas. Part of it is being impatient with insincere companies.
Gosh. I find myself getting really riled up by this article. I work on the Shuttle External Tank, so I see every day how demanding, how difficult and precise manned space flight has to be.
I have a lot of respect for the suborbital tourism industry, and for SpaceX, since they're both doing very difficult things, too (getting a human to the boundary of space, and getting a payload to orbit without government funding, respectively).
And here, this guy just waltzes in and claims he can do all of that and more for a low, low cost of $4 million and a bad Photoshop of a Lear Jet with "rocket" and "propellant tank" drawn on the fuselage? Cripes!
In fairness, they don't need to reach escape velocity. Just orbital.
But they won't be able to do that either. Someone down thread offered damning reasons why the aeronautics don't add up, and I can tell you right now: there is NO way this works from a propulsion point of view. Plus, the writing style is so immature; it's obvious the interviewer knows very little about space flight (or is criminally incurious about the answers he gets).
Excellent analysis. I described some other problems, mostly from a propulsion perspective, in my post. How did this "article" get up here? It's a glorified press release, and it doesn't even make sense internally.
Well, it clearly wasn't RobGoldsmith's fault. The article does indeed claim this business-jet sized craft will reach orbit. The first stage would be a tow plane.
I'm just not seeing this. The tow plane can get the vehicle to a moderate altitude, but nowhere near orbital velocity (delta-v=20,000 km/hr, after drag?). You'd need a mass ratio of 10-to-1 on propellant ("easy" with a capsule that jettisons everything behind it; much harder with a space plane), and you'd have to be using something with an extraordinary Isp, around 320. That probably means cryogenic propellant. So this plane is made of cryo-compatible low-weight, reusable materials? Are there turbopumps on board? I don't see a rocket engine, I see a nozzle. OMS? Reentry heat shield? How do you restart your engine for a controlled reentry burn? Do you keep propellant in those tanks for that? Have you accounted for O2 slosh?
This just doesn't LOOK like an orbital vehicle. To build an orbital craft with that profile and no significant 1st stage would require ludicrous developments in materials science.
And his answers come across as insanely naive.
"Our proposed flight profile from launch to orbital insertion enjoys the same level of safety as conventional aircraft."
No, it can't possibly. You don't even have a prototype, so I can't even entertain such a statement.
"Towing aircraft is common and NASA successfully demonstrated towing a space plane."
NASA hasn't demonstrated a space plane, so how can they have demonstrated towing one? They may have demonstrated towing a REGULAR PLANE. It is true that NASA has launched orbital missiles from airplanes (not via tow, however, to my knowledge).
"One thought I had was that the complexity of this vehicle may actually cause more safety issues, I was told that its simplicity and reliability are un-matched in any other system."
Oh, well that settles that, then. Who wrote this?
"With regards to cost I was also told that a prototype would cost $4 million USD."
That won't even pay for your propellant. For reference, a new Lear Jet STARTS at $5 million. That's off-the-lot; all development costs behind it. So an orbital space plane costs less, including R&D than a Lear Jet? How about the tow plane? Does that come free?
"The design can easily be scaled up, both in terms of the first stage capability and the capability of the parent vehicle."
No, spacecraft do not "easily" scale up. You pick your target orbital payload mass/velocity and you do whatever it takes to get you there. You can't build an orbital, man-rated spacecraft, and then just multiply the entire thing by 1.3.
"The project is currently getting a team together and looking towards getting funding."
So, really, no design yet?
I read up a bit on Robert Talmage. His expertise seems to be in rescue/escape vehicles. I think this entire thing is a publicity stunt for his cockpit-jettisoning escape system (which is all they really talk about in that article; they don't mention fuel or engines once), which, for the record, seems to depend on lifting surfaces:
"After separation, the EV (which is designed to fly at higher dynamic pressures than the parent vehicle) will naturally pitch down and accelerate. Releasing the forward weight of the EV will cause the parent vehicle to be out of balance. With the center of gravity now well behind the center of lift, the parent vehicle will be unstable and pitch up. The high drag configuration of the unstable parent vehicle will provide good horizontal separation from the EV."
...so it wouldn't even work in orbit.
I'm sure Mr. Talmage has some hand-wavy answers to all of these questions, and I would LOVE to get my hands on a $4 million space ship. But I think it's safe to say this guy has his head in the clouds, not his hardware.
"The TAAS Company have released details on their new Orbital Space Plane."
Is the word "orbital" being used in some context I don't understand? This vehicle does not appear to be anywhere close to capable of reaching orbit. "Suborbital space plane," I can get behind.
I work in CFD, so this is all thrilling to me. I suspected it was only a matter of time before methods were discovered for applying quantum computation to large systems of linear equations, and I certainly hope your work stands up to peer review. Cheers!
I don't know if this has come up already, but there's a handy online circuit simulator here: www.falstad.com/circuit
You can create circuits from scratch or load and play with a large library of existing circuits. I used it a lot in grad school when I had to build something electronic for the lab, just to make sure it was going to do what I expected.
Slashdot Mirror
I am not well versed in regenerative biology, but my girlfriend happens to be getting her PhD in that field. I sent her this link for comment and here's what she said:
From article: "The wounded Marine's recovery is particularly exciting for scientists as it involves the regeneration of skeletal muscle which ordinarily does not grow back"
From any book in any regenerative scientist's library: "It has been known for more than a century that skeletal muscle, the most abundant tissue of the body, has the ability to regenerate new muscle fibers after it has been damaged by injury or as a consequence of diseases such as muscular dystrophy (1)"
(in this case the reference = Carlson BM. The regeneration of skeletal muscle. A review. Am J Anat. 1973;137(2):119–149. View this article via: PubMed CrossRef)
Annoying! Maybe he is on to something that really does help quicken the natural regeneration response or promotes better healing or something, but no one will ever know because there are no controls. He has no mouse controls... he obviously can't do human controls and people are just slapping this stuff on there because... "at least it doesn't hinder the response". (but he could be charging billions for a placebo!)
Oh well. Science is stupid. The media is even dumber.
In other words: Slashdot, please stop posting articles from the Daily Mail. Also, on background, I know the doctor mentioned in the article, Badylak, was kicked out of his group for poor research practices that included trial by media instead of peer review. This sort of publicity piece is his MO.
They don't test shuttle tanks in Mississippi.
They could have tested in Florida and in fact did do some testing for a 240" solid booster in south Florida and they test Centaurs in West Palm to this day.
The large space? They where building the VAB so building a production building in Florida would have been simple.
There is a good reason for it to be Louisiana instead of say AZ. But the reason that it wasn't in Florida was to spread the "wealth" around.
In many ways it isn't a bad idea if you look at maximizing the economic benefits or a program. But if you look at just the cost it adds up.
That is one of the good things about a lot of big government programs like that.
Yes they cost a lot of tax dollars but a good amount of that money gets recycled from the jobs that it creates.
You also have the RnD benefit as well.
I am not even saying that this is the worst or best way to do these projects. Just that is the way they are done.
Actually, they DID test the space shuttle tanks in Mississippi. See here: http://en.wikipedia.org/wiki/MPTA-ET. They don't test every tank there, but they tested the early ones and they test tanks that have certain kinds of problems, such as leaks.
As for building the tanks in Florida, the Kennedy VAB in Florida is 8 acres. The Michoud facility in New Orleans is vastly larger: more than 43 acres. Saying "because they built the VAB in Florida they could have built a manufacturing facility for large scale boosters" shows little knowledge of how the tanks are produced and how much space it takes to produce them. There was an existing 43 acre facility laid out to produce large scale industrial products in LA that the government already owned. The only additional cost of putting production there was barge traffic to Mississippi/Florida. Compare that to the cost of building a new 43-acre environmentally controlled facility from scratch in Florida, and I don't think that's a trivial decision. You can convince me, but you haven't thus far.
I'll freely admit that most of the Michoud space is not currently used. Original production plans were to produce one or two tanks per month, which grossly overestimated the Space Shuttle's turnaround efficiency. In the end, much of the Michoud capacity was not needed. But if you want to make the argument that Michoud was selected wholly or even primarily as a political favor, you have more homework to do.
I can't speak to the other cases, but they built the first stage of the Saturn V in Louisiana because... 1. They needed a very large industrial space. The factory is a converted aircraft production facility built during WWII. 2. They needed deep water access to ship the giant vehicles. External Tanks and the Saturn S-IC cannot be shipped by road or rail. 3. The selection was tied to accessibility of both Kennedy Space Center in Florida (for launching) and Stennis Space Center in Mississippi (for testing). Once you start to pick a few locations, logistics become non-trivial and your next choice becomes more constrained. I can't assure you that graft had nothing to do with it (can you assure me that any part of any government program in history didn't have some back-deal component?), but the locations were not selected purely for political effect.
I totally agree; I too was left very concerned after reading his thoughtful and thorough analysis. And I'm really disappointed that (practically) no one on Slashdot took a look at it. Especially after reading his analysis of confirmation bias and so on, the knee-jerk responses on this thread are particularly disheartening.
The law review article upon which the linked story is written is 80 pages long. It is, as best I can tell, totally consistent with known science (it doesn't postulate "black holes destroying the universe" or any such nonsense). It is an attempt to do 3 things:
1. Ask how a court ought to address a science experiment that could, by some very unlikely chance, destroy the earth. He uses LHC as an example, but also suggests Strong AI and nanotechnology as possible future examples.
2. Analyze how a non-expert court can, or should, evaluate highly technical and possibly controversial scientific claims for and against the safety of a bleeding-edge research project.
3. Analyze how logical or cognitive errors could realistically lead a scientist to accidentally or intentionally understate or mischaracterize the risks of her research.
Anyone on this board droning on about "Shut-up-the-LHC-can't-destroy-the-world" either DRTFA or totally misunderstood it. I will now quote the author:
If he had chosen anthropogenic global climate change as his topic of analysis, I think there would have been a more interesting debate on Slashdot, but apparently any mention of "LHC" in the same breath as "black hole" causes some sort of hysterical allergic reaction in some people.
They still are broadcast! Well, on basic cable anyway. I get to work launch support for the External Tank from here in New Orleans (which is kind of like sitting at the kiddie table of the "real" launch support at Johnson Space Center), and we actually watch the launch on live TV, along with our official NASA video feed. Sometimes the TV version is more informative, frankly.
Wow, quite a lecture!
You're right that LOX isn't as cold as some of its cryo kin, but it's so damn heavy and reactive that I would still argue that using it would be beyond anything this designer seems to be accounting for. Even loading it is a problem, because it gassifies and takes time to reach optimal density, hence the replenish loading cycles on most LOX systems. And remember also that the author claimed he could launch without substantial ground support.
No ground support, but you want to use cryogenic propellants? I mean, this guy is delusional! (The author, not you).
Scaled Composites did their best to build a composite tank that could safely and repeatedly handle N2O, which should be a better-behaved oxidizer, and they still managed to blow one up and kill a few technicians. A different system, of course, but if you read the article, it just seemed like the author was completely insane about the difficulty of pulling this stuff off.
As to the nozzle savings, I used to have a chart that explained the penalty a nozzle suffers in thrust due to over-expansion at sea level and under-expansion in the upper atmosphere, but I can't find it. Maybe you can correct me; I don't think the savings gained by starting the engine at altitude would be tremendous unless you could tow to above 30,000 ft, when using a large area ratio becomes really advantageous. Could the tow vehicle get you that high? Remember, you're carrying an awful lot of heavy propellant. And remember also that the author promised development costs of $4 million, total! I think you'd need a heck of a tow vehicle, one that would cost well north of $4M.
Anyway, thanks for elevating this conversation with some really great examples, putting the necessary Isp in perspective.
Manned space flight will have to be demanding and precise no matter who does it. You're right that the "difficult" part may have more to do with NASA than anything.
Otherwise, I totally agree. The shuttle was deeply flawed, and NASA is a deeply dysfunctional organization. But for all its flaws, the shuttle is real and not imaginary.
Of course, the shuttle has cost real dollars and real lives, whereas this fellow's fantasy ship hasn't hurt anyone and probably never will (because nobody would fund it). So I guess to be morally consistent, I would be better off directing my ire at NASA.
But there's a certain arrogance and laziness in the posted article. It's like it can't even be bothered to pretend to be a real spaceship.
One can argue that, for all its flaws, the shuttle was an earnest attempt at creating a revolutionary space architecture. One doomed by bureaucracy, politics, mission creep, economics and technological deficiencies, perhaps, but REAL.
I'm all for privatization of space, and part of privatization is criticizing the hell out of weak proposals. Part of it is getting a little angry at inferior products and ideas. Part of it is being impatient with insincere companies.
Gosh. I find myself getting really riled up by this article. I work on the Shuttle External Tank, so I see every day how demanding, how difficult and precise manned space flight has to be.
I have a lot of respect for the suborbital tourism industry, and for SpaceX, since they're both doing very difficult things, too (getting a human to the boundary of space, and getting a payload to orbit without government funding, respectively).
And here, this guy just waltzes in and claims he can do all of that and more for a low, low cost of $4 million and a bad Photoshop of a Lear Jet with "rocket" and "propellant tank" drawn on the fuselage? Cripes!
Of course, of course. It wouldn't even be a spectacular failure; I don't think it could get that far.
In fairness, they don't need to reach escape velocity. Just orbital.
But they won't be able to do that either. Someone down thread offered damning reasons why the aeronautics don't add up, and I can tell you right now: there is NO way this works from a propulsion point of view. Plus, the writing style is so immature; it's obvious the interviewer knows very little about space flight (or is criminally incurious about the answers he gets).
Excellent analysis. I described some other problems, mostly from a propulsion perspective, in my post. How did this "article" get up here? It's a glorified press release, and it doesn't even make sense internally.
See my own reply to my comment down thread. There are a number of GIGANTIC red flags here.
I'm not saying it's impossible. I'm saying that if it IS possible, the designer is the greatest engineering genius who has ever lived.
Well, it clearly wasn't RobGoldsmith's fault. The article does indeed claim this business-jet sized craft will reach orbit. The first stage would be a tow plane.
I'm just not seeing this. The tow plane can get the vehicle to a moderate altitude, but nowhere near orbital velocity (delta-v=20,000 km/hr, after drag?). You'd need a mass ratio of 10-to-1 on propellant ("easy" with a capsule that jettisons everything behind it; much harder with a space plane), and you'd have to be using something with an extraordinary Isp, around 320. That probably means cryogenic propellant. So this plane is made of cryo-compatible low-weight, reusable materials? Are there turbopumps on board? I don't see a rocket engine, I see a nozzle. OMS? Reentry heat shield? How do you restart your engine for a controlled reentry burn? Do you keep propellant in those tanks for that? Have you accounted for O2 slosh?
This just doesn't LOOK like an orbital vehicle. To build an orbital craft with that profile and no significant 1st stage would require ludicrous developments in materials science.
And his answers come across as insanely naive.
No, it can't possibly. You don't even have a prototype, so I can't even entertain such a statement.
NASA hasn't demonstrated a space plane, so how can they have demonstrated towing one? They may have demonstrated towing a REGULAR PLANE. It is true that NASA has launched orbital missiles from airplanes (not via tow, however, to my knowledge).
Oh, well that settles that, then. Who wrote this?
That won't even pay for your propellant. For reference, a new Lear Jet STARTS at $5 million. That's off-the-lot; all development costs behind it. So an orbital space plane costs less, including R&D than a Lear Jet? How about the tow plane? Does that come free?
No, spacecraft do not "easily" scale up. You pick your target orbital payload mass/velocity and you do whatever it takes to get you there. You can't build an orbital, man-rated spacecraft, and then just multiply the entire thing by 1.3.
So, really, no design yet?
I read up a bit on Robert Talmage. His expertise seems to be in rescue/escape vehicles. I think this entire thing is a publicity stunt for his cockpit-jettisoning escape system (which is all they really talk about in that article; they don't mention fuel or engines once), which, for the record, seems to depend on lifting surfaces:
I'm sure Mr. Talmage has some hand-wavy answers to all of these questions, and I would LOVE to get my hands on a $4 million space ship. But I think it's safe to say this guy has his head in the clouds, not his hardware.
"The TAAS Company have released details on their new Orbital Space Plane."
Is the word "orbital" being used in some context I don't understand? This vehicle does not appear to be anywhere close to capable of reaching orbit. "Suborbital space plane," I can get behind.
I work in CFD, so this is all thrilling to me. I suspected it was only a matter of time before methods were discovered for applying quantum computation to large systems of linear equations, and I certainly hope your work stands up to peer review. Cheers!
I don't know if this has come up already, but there's a handy online circuit simulator here:
www.falstad.com/circuit
You can create circuits from scratch or load and play with a large library of existing circuits. I used it a lot in grad school when I had to build something electronic for the lab, just to make sure it was going to do what I expected.