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The ESA wants to use the Energia rocket for its human mission to Mars as you can read from this Executive Summary (PDF) from ESA. (look at chapter 6.3: MISSION ARCHITECTURE-->Launchers and chapter 7: Conclusion, the fourth bullet)

So the ESA is ahead of you on this point.

While I cannot claim to be an expert on thermal analysis, I have been working as a software expert in ESA's spacecraft testing centre for the past six years, writing and maintaining the software used to gather, process, and present thermal data during thermal testing. The big device in the top-left corner of the image is ESA's Large Space Simulator, and the little room a little to the right of that is my office ;-)

A thermal test typically lasts a few weeks, and we would typically be gathering data from 1500-2000 sensors (mostly thermocouples and PT100's) on the spacecraft, plus another 1000-1500 from the facility itself (depending on configuration). This adds up to a couple of gigabytes worth of data.

Right now the first ATV (the Autonomous Transfer Vehicle that is scheduled to bring freight to ISS starting next year or so) is being prepped for testing, somewhere at the end of this year.

Since this is /., I should probably add that for presentation and control of the system we use a mix of HP-UX (for historical reasons) and Windows XP PC's. Our main server is an aging HP-UX machine, which we will soon be replacing by a Linux solution. I've been gently pushing Linux for a while now, but one of my problems is that many of the acquisition systems require GPIB support which is hard to find under Linux (there are no drivers available for HP cards).

There are guided tours from the Space Expo, if you are interested.

Actually, they dont just fall. I joined a vomit comit last summer in ESA's zero-g student campaign flight. http://www.estec.esa.nl/outreach/parabolic/pfc_bas ics_frame.htm And what they do is to fly a parabola, and both upwards and downwards, the plane is accellerating towards the earth with one g, and making it's inventory experience near zero g As for the time, its not usual to get more than 20-30 seconds. From level flying you first enter a steep cimb up to 45degrees, with max 2-2.5g acceleration. Then you have approx 100m/s speed upwards, in additioon to your 200m/s speed forwards. After approximately 10 seconds, you are left with no speed upwards, starting to fall. After falling another 10 seconds you have a 100m/s downwards speed, time to brake! The plane then flattens out and and gives it's inhabbitants another couple of g's to stop the downwards flight. If your in the crazy corner, you can fall for 30 seconds, giveing you 30*g=300m/s, and if you have this speed before you start the parabola, you can have a minute zero-g, but: You have then fallen .5*g*30^2=4.5km, and if you decellerate with one g (in addition to the earth's so it feels like two), you nedd another 4.5km to stop. In addition you need one mother of an engine pushing you to near sonic speed upwards... When we flew, this was repeated 30 times, with a minute pause. None of the 30 students womitted, so the name is more fun than true. K

I recently had the pleasure of attending a talk by a guy that worked on the focal plane of GAIA, a spacecraft to be launched by ESA around 2010. It is not designed for imaging, but for very accurately determining the position of stars (astrometry).

Their specs for the focal plane of the telescopes: size of around 0.6*0.8 meter, 180 CCD chips packed together for a total of 1.2 Gigapixels! I believe handling the thermal power alone (~100 Watt), without moving the location of the pixels a bit already was a typical case of rocket science.

Couldn't gravitational lensing be a possible means for testing frame dragging?

Theoretically, yes.... there's a recent paper that works out the numbers for lensing from a spiral galaxy, and it's roughly on the order of a few micro-acroseconds. Possibly detectable by SIM or GAIA.

[TMB]

Why is there no possibility of a manned mission to L2? Some people at least are thinking about it. Why not have a station out there? Relatively stable orbit anyways.

No prediction of the cosmic microwave background's blackbody temperature prior to the CMBR's discovery was ever thought very likely correct

Predictions were made, though, from Steffan-Boltzmann laws, of blackbody cosmic background radiation in an infinite/static universe configuration by Guillaume in 1896 (5-6K), Eddington in 1926 (3.18K), Regener (2.8K) and Nernst (0.75K on a tired light model).

It is the mere existence of the microwave background -- its omnidirectional uniformity and amazing blackbody spectrum -- that is the prediction of interest. And contrary to assertions from people, these are extremely hard to contrive in other ways. Such alternative sources for the CMBR typically involve a local origin, in which starlight is thermalized by e.g. the intergalactic medium.

I had gathered that inflationary theory was employed to explain the uniformity due to horizon considerations; fluctuations contributing to the anisotropy would have had to be in contact. Without inflationary theory, it would/will be much harder to explain, at least on that basis.

I wasn't aware of a localized requirement for alternate explanations of the CMB, although many of the proponents in the early part of the last century employed them. I've heard in passing of the "whiskers and grains" afficionados, but don't know what to think of them. So the limitations of an alternate explanation would be: high density IGM so that it can be isotropic with an explanation of how it can avoid absorbing extragalactic signals, or low density IGM and a very old universe and an explanation of what would thermalize radiation independently of distance.

Such theories also tend to neglect the Sunyaev-Zel'dovich effect

One thing I found particularly odd about the effect was its independence from redshift. From an alternate standpoint, I would ask why it could not be considered a constant effect on a constant temperature of background radiation.

(On a side note: I must thank you for giving me some very interesting topics to look up. Here's one link for the S-Z effect for those watching the conversation not in the know. :)

Third, inflation does not give us an age of 13.7 Gyr for the Universe.

Fair enough.

From the WMAP data, NASA scientists precise estimate of 13.7 Gyr +/- 0.2 Gyr. It is said to discount certain models of inflationary theory, but appears to rely on it.

One gets an age of 13.7 Gyr if the Universe is flat, if its energy content is basically all matter, and if the Hubble constant is 50 km/s/Mpc.

The values from NASA give 4% visible matter, 23% dark matter, 73% dark energy, at a Hubble constant of between 68-75 km/s/Mpc, and indicate a flat universe.

If inflation turns out to be complete and utter crap, that does not say anything for or against the Big Bang model, since the Big Bang model does not have inflation as one of its components.

Perhaps not, but a lot has been invested in the inflationary path. It would look bad :)

And when it specifically comes to the acceleration of the expansion, that's been observationally detected, since 1997, by independent groups, and is one of the key pieces of evidence arguing for a nonzero vacuum energy density.

I can imagine how accelerating expansion could be deduced, but I've seen nothing (point me in the right direction?) to indicate that there are observations that would indicate acceleration independently of the current BBT models and equations.

I don't doubt that BBT is self-consistent, but for convincing "outsiders", stock must be taken of which observations whose interpretations shift depending on context, and which ones are more "static". If you've ever argued with a orthodoxie/fundie, you

Here's a "close together" example:
http://www.estec.esa.nl/conferences/FPD/info/tos-m m981104.html

Here's a short paper minus images on telescope arrays:
http://www.atnf.csiro.au/technology/future/2001oct /bthomas_ska_site.html

"The maximum extent of LOFAR is 350 km"

It seems there are proprietary astronomers who like proprietary programmers always think bigger is better when in fact smaller, more spread out is the best choice.

In principle the resolving power of a telescope depends on its diameter -- a bigger one can see finer detail -- but in practice atmospheric turbulence, the same effect that makes stars appear to twinkle, blurs the stars and erases fine detail. This is why the Hubble, even though it is not large, only about 2.4 meters (96 inches), compared with the new giants on the ground, can do breathtaking work.

The proposals sport Brobdingnagian names like the California Extremely Large Telescope, or CELT; Giant Magellan; or the Overwhelming Large Telescope, OWL, a 100-meter-diameter behemoth being contemplated by a collaboration of European nations. And their proponents promise appropriately outsized scientific results.

However offensive your remarks about Mary might be

Interesting how it's only offensive when it's about your religion. I said the exact same thing about Alcmene (Hercules' mother). I'm sure someone somewhere still worships the Greek/Roman pantheon. Just how seriously would you take it if they complained about about my "offensive Alcmene remarks"?

fulfilled prophecies in the Bible

That's not exactly a unique claim. The Koran and other holy books also have "inerrant fulfilled prophecy". Bible "proofs" like the supposed prediction of the formation of Israel in 1948 are just as bogus as any of the Nostradamus prediction proofs.

And bible prophesy generally means you are talking about old testament, and if you go to old testament that means you're talking about a pretty evil god. A mean, nasty, petty, vengeful god who orders armies to slaugher innocent children.

Evolution:
I looked at a lot of links, but I couldn't find one that was clear, easy and complete. Here is one, and here are lot more, but maybe it will be better if I try explaining it myself. Appologies if I over-explain something, without immediate feedback it's usually better err in that direction than to risk underexplaining and confusion.

First I have to introduce the concept of a schema (plural schemata). A schema is a sub-pattern. For example look at the words "TRACE" and "PRICE". They both have a second letter of R, a fouth letter of C and a last letter of E. If we use a questionmark as a wild card character we can write that schema as "?R?CE". Both "TRACE" and "PRICE" contain that sub-pattern.

Now look at the words "INTRODUCING" and
"INTERFERING". They both have the schema "INT?????ING". But that is merely the biggest schema they share, there are actually 64 schema they share. Here are a few:
??T????????
I???????I??
IN?????????
INT?? ???I?G
????????ING
I?T?????IN?

If you string together 12 random letters it is absurdly unlikely to make a word, but if you include valuable building blocks your chances go way up. For example the schema ?????????ING is a particularly high value building block. A group a letters ending in ING is much more likely to be meaningful.

The word "BUG" has 8 schemata: BUG, BU?, B?G, B??, ?UG, ?U?, ??G, and ???. Usually valuable schemata have letters clustered close together, but look at the schema B?G. It has a hole in the middle, but it is a valuable schema: BAG, BIG, BEG, BOG, BUG. A hole in the middle of a schema of a neurotransmitter gene can be good because filling in that hole in different ways can make a variety of related neurotransmitters, or even a similar protine with an entirely different function.

Any 3 letter word has 8 schemata (2^3 = 8), but any string of 20 letters has over a million schemata (2^20). DNA is a string of billions of base pairs with a near infinite number of schemata.

The power of evolution lies in implicit parallelism. Normally when you think of evolution you think of individuals being "tested" and multiplying or dying. But instead look at the whole population and the frequency of every schema in that population. When you "test" an individual to see if he survives and reproduces you are actually testing every single schema within that individual simultaneously. That is the implicit parallelism. If course it's not as good as pure test of each schema individually, it is a weighted mix of all of them. Many schema are meaningless and have no effect, some are important and have a big effect. Across a large population any schema which has even a minimal benefit will become slightly more common in the next generation and any schema that is even slightly harmful will become a little less common.

Mathematical analysis sho

Maybe they're referring to the Cassini mission that arrives at Saturn next year? Here's a good site for basic info.

Well, most of the effort from European Union countries comes through the European Space Agency. This is why it's probably okay to classify them as "the europeans". They've not done any solo manned stuff yet, but have done a lot with space probes and unmanned missions.

Although they don't have manned launch vehicles of their own, they work with the Soviets and with NASA. Their highest profile manned project is their work on the International Space Station - both in terms of supplying space hardware and astronauts. Their most notable unmanned project is the groundbreaking joint-NASA SOHO sun observation probe.

Upcoming projects of note: a manned Mars mission is in the (very) early planning stages.

It seems as though international cooperation should be the *only* way to go when it comes to grand plans such as reaching Mars. If NASA, ESA, China, India and the Soviets all put their differences aside and pulled together - humanity could become a truly spacefaring species within our lifetimes (graduating from a "type 0" to a "type 1" species that has mastered interplanetary travel [where type 2,3 = extra-solar and galactic travel).

Dunno about Theo, but the European Space Agency has made a sparc compatible integer unit called LEON-1. They say they will use it on future space missions.

Here is a scenario that *might* work in the future: once ATV (ATV ) becomes available, it could be detached from the space station and sent down to pick up the people from the shuttle. It could then fly back to the space station and deliver the shuttle crew there.

Doing this would require proper docking equipment on the shuttle, life support equipment on ATV (which, interestingly, is being implemented as far as I understand), and appropriate flight software to allow the docking to take place.

Well, the Europeans seem to be looking at the past for inspiration. Apollo-style reentry vehicles are cheap and reliable. And I'm not sure whether they are exciting for you, but I suspect they are quite exciting for everybody on board.

that does not involve getting off the ground by blasting itself off the ground with hundreds of pounds of fuel.

Well, it just takes a certain amount of fuel to get stuff up there. However, the shuttle greatly compounds that problem by wasting half or more of the weight on just the same chunk of metal going up and down over and over again, only to give astronauts a much riskier ride.

Whoo! I guess satellite computers were pretty smart.

Show them the moon lander through a telescope, they say the telescope has been tampered with.

Thats the whole point of these debunking missions you can't see the lander on the moons surface or the rovers, even with modern telescopes the size relationship between the lander and any earth based telescope is just too small its like looking for a grain of sand from 100,000 miles away.

I believe Japan is launching a mission in 2003 to photograph the moon (called LUNAR-A) from a hi resolution camera on a low orbit satellite , also a californian company is doing the same with a mission called Trailblazer which also should prove/disprove that mankind was indeed on the moon.
In order to see if someone is lying you cannot ask the said lier to show evidence especially if fabrication of evidence was an issue in the first place , that is why its probably a better idea for a independant non connected 3rd party to verify the accused lier's claims.

Of course this still probably wont be enough for the hoax/conspiracy believers as they will say NASA skewed the results or "tainted" the 3rd party.

You must remember, we live in an age of liers and fraudsters and no one is untouchable even a established science agency such as NASA or members of the American goverment, after all no one thought Enron or AC would be one of the biggest frauds in history so it is somewhat understandable that people don't believe everything they see

But for the "ignorant" masses an independant investigation will go a long way to dispell any doubts, especially from one by a country independant from that of the said "fraudsters", plus with any luck they might be able to complete some worthy science along the way.

Sure, the astrometry (positions) in Hipparcos are better than in Tycho 2, and Hipparcos contains more information about the stars than Tycho 2 (e.g. variability), but still. I would in fact think that Tycho 2 would be better for SETI than Hipparcos, but they may have their reasons.

The full VHDL code (what you need to synthesize a chip, send this to a fab and they send you back a fully functional microprocessor) is available under the LGPL. Their chip (Leon) is truly free (as in free speech) hardware.

What format and storage medium you adopt for truly long term data storage is still a thorny issue. The only medium we know can survive this long, and which has a reasonable data density, is good old fashioned acid-free paper and ink. This was the approach that the Hipparcos Project, a satellite mission to measure the positions and motions of stars to unprecedented accuracy, chose for their long term archive. As well as electronic storage, they published a paper catalog in books using acid free paper, long duration inks, and a font specially designed to make OCR easy, and then made sure that lots of different libraries, scattered over the world, had copies.

We still can't beat paper for durability.

You can also hear the meteors as they whiz past Earth.

They disrupt radio frequencies and cause them to rebound back into Earth's atomosphere.

This experiment back in 1999 did just that. I realize this is dated but you can listen to them youself.

...use your FM receiver with an external aerial. Try to find a station a long way away (that's the difficult bit, as usually a nearby station gets in the way). Under normal circumstances the transmission should be difficult or impossible to detect, but when a meteor intervenes the signal jumps over the horizon and a brief fragment of the transmission can be heard. Depending on the type of transmission, it might sound like a tone, a fragment of music or voice, or simply noise. Contact lasts for as long as the meteor train persists, usually from 100 milliseconds to a few seconds.

Note that they are most likely using GNU software. Here is a list of the software development environments for these chips, and Here is the European Space Agency's web page for the tools and emulator.

Pfew. I was worried for a second there.

The SOHO pictures are just beatiful, especially the movies.

I'm not an astronomer, but I think this big one is visible on the "LASCO C2" just around the '11:00' timestamp on Sept 1.

Too bad the EIT movies are not current. I guess it was almighty Murphy who choose this week-end for the flare...

Pfew. I was worried for a second there.

The SOHO pictures are just beatiful, especially the movies.

I'm not an astronomer, but I think this big one is visible on the "LASCO C2" just around the '11:00' timestamp on Sept 1.

Too bad the EIT movies are not current. I guess it was almighty Murphy who choose this week-end for the flare...

As the SMART-1 site itself makes clear:

SMART-1 is to be the first European spacecraft to travel to and orbit around the Moon. It will also be the first time that ESA employ electric propulsion as the mission's primary propulsion. Electric propulsion on an interplanetary mission has been used only once to date, on NASA's Deep Space 1 probe launched in October 1998.

...

The electric propulsion technology to be employed by SMART-1 was initially developed over 30 years ago, notably in Russia which, since 1972, has launched a number of operational spacecraft placed in Earth orbit. They used electric propulsion for attitude and orbit control in addition to the classical chemical propulsion. In the early 90s, agreements were reached between Russian, American and European industry, notably SNECMA, France, to pursue the development and commercialisation of such thrusters.

...

In recent years commercial telecommunications spacecraft built in the United States using different types of electric thrusters have been launched. The first was the Hughes PanAmSat-5 in 1997

source

The main objective is to test a new type of engine technology - solar electric propulsion - which could power future missions very long distances into deep space

Still determined to live in the Space Age

TomV

No, you're not. And what I like most about this story is that, when you follow the links through to the ESA SMART-1 stuff, you can see that, underneath all the grown-up grant-aided professional image, they've got the same wide-eyed enthusiasm we got sitting in front of those broadcasts - Apollo 11 and the other moon landings I can just about remember being sat in front of because this was important, but Apollo-Soyuz I was old enough to have some idea why it was so important and exciting.

And when we look at the SMART-1 site, what do we see? Lunar survey craft, great in itself, about time too, but in addition, it's a test mission to see if their ion drive (with pretty blue exhaust) will do the job for their probe to Mercury

It's great to see that the ESA understand the importance of keeping this stuff exciting, and of communicating that excitement with the public. It's my tax money that goes into this, and I'm very happy to see what they're doing with it.

Because, 27 years ago, I was really looking forward to living in the Space Age, and it seems to have been mislaid somewhere in the intervening.

TomV

Unfortunately, even though an inflatable module was considered for the ISS, it was not built. Pretty much all our space engineering seems to be done in terms of big, heavy, metal structures.

Interest seems to be picking up, though. There has been a workshop at ESA recently.

anyone who has anything to do with a standards body nowadays know's that people try and hijack standards so their tech/patent gets into it

this way if you implement the standard you have to pay

you can't have an opensource MPEG 4 without paying 3million bucks when you distribute it and they call that a standard

ok real hardware and software

in terms of a kernel their is in My Humble Opinion

Linux

Open BSD

netbsd for every arch under the sun (joke included)

then we have the problem of hardware

Opencores provides some of the effort BUT my favorate is

LEON-1 VHDL model
- Functional SPARC compatible processor core integer unit. Runs on Altera, Mietec, Temic MG2, Xilinx. Developed for space missions. Implemented as a highly configurable, synthesisable GPL VHDL model.

Altera 10K200E FPGA or Xilinx XCV300 enable this you can also get a LCD and keyboard AMBA devices from www.gaisler.com

what I would like is a machine that you could say that the whole thing is opensource

regards

john jones

If the instrument is only a refinement of existing ones, it's a matter of simple calculations what size/weight planets should be detectable with it. A little Googleing brought me here, with planet-figure.pdf being a diagram of Planet Detection Methods, and planet-paper.pdf being a (longer) paper.

Please check out superconducting tunnel junction technology, which is the basis for detectors that can measure the frequency of impinging photons. No need for separate RGB pixels - stacked or not - because each pixel can determine the exact frequency or wavelength of each photon it detects. You can take a spectrum and create an image in one exposure with one detector, without using any diffraction gratings or RGB filters.

Well, we actually have a pretty good idea which are the closest ones within a few hundred light years (barring the really dim red dwarfs and whatnot, of which there are probably plenty). The Hipparcos mission, flown by the European Space Agency did an all-sky survey of the distances to over 100000 stars by measuring the "wobble" of these stars relative to the backround as the Earth moves around the sun (called parallax).

An even more exciting mission is coming up in the next decade or so called the GAIA mission which will get accurate measurements for the distances of over one billion stars (about 1% of the entire galaxy!)

Well, we actually have a pretty good idea which are the closest ones within a few hundred light years (barring the really dim red dwarfs and whatnot, of which there are probably plenty). The Hipparcos mission, flown by the European Space Agency did an all-sky survey of the distances to over 100000 stars by measuring the "wobble" of these stars relative to the backround as the Earth moves around the sun (called parallax).

An even more exciting mission is coming up in the next decade or so called the GAIA mission which will get accurate measurements for the distances of over one billion stars (about 1% of the entire galaxy!)

The ion drive aboard the DS1 broke several records with its stellar (literally) tortiose-vs-hare performance. Does anyone know if this technology has any potential for being adapted to the ISS?

I don't think ion propulsion is being considered for ISS right now, although it is being used for stationkeeping thrusters on a number of satellites (the XIPS system was developed by the former Hughes Space & Communications, now Boeing Satellite Systems, for commercial communications satellites.) The European Space Agency's Artemis experimental communications satellite is also using ion propulsion to adjust its orbit, after its Ariane 5 launcher malfunctioned and placed it in the wrong orbit.

A common misconception is that genetic algorithms are based on mutations. For example someone here said:
random mutations used in genetic programming are about as efficient as real random mutations. They get the job done eventually, but require a lot of screw-ups to make one improvement.

Mutations are a red herring. Genetic algorithms produce results faster without mutations. The benefit of mutations is that they allow the search to go farther - potentially indefinitely - and produce better results.

The power of genetic algorithms comes from impicit parallelism. This can increase the search rate by a factor of over a billion. There is a complicated mathematical anaylsis, but here is a description:

one of a genetic algorithm's most important qualities is its ability to evaluate many possible solutions simultaneously. This ability, called implicit parallelism, is the cornerstone of the genetic algorithm's power. Implicit parallelism results from simultaneous evaluation of the numerous building blocks that comprise the string. Each string may contain millions of these building blocks, and the genetic algorithm assesses them all simultaneously each time it calculates the string's fitness. In effect, the algorithm selects for patterns inside the string that exhibit high worth and passes these building blocks on to the next generation.

This field has a name/acronym: HALE

High Altitude/Long Endurance.

Here's a (fairly stale)
Page of Links

The overall concept is to supplant/replace/augment satellites and/or aeroplanes.

BugBear

What are your predictions on free hardware?

I don't realy want to get into a long technical discussion about antenna design since it is a big subject. But, in summary, any antenna defined by clear physical dimensions tend to be narrow band (for example a dipole which clearly is primarily defined by a single measureable length). To make a good wideband antenna you need to find a structure defined more by angles. At this point I realy need diagrams. I suggest that you stroll over to Tecom's wideband antennas catalogue and look at some of the pictures (some are sadly hidden by radomes, but there are some reasonable examples).

For a simple wideband design like a conical log spiral the lowest frequency is a function of how big you make the big end (limted by cost and obvious size constraints) and the highest frequency depends on how small you can make the pointed bit (limited by power handling, ruggedness and how good your soldering is).

Fractal antennas are based on the same premisse that if you can't quite pin down how big your antenna is then is must be wideband, but instead of trying to make an antenna defined purely by angles you have lots of dimensions from big to very small and everything inbetween. There is nothing wrong with this concept and it works. The problem is that it doesn't do anything about the basic laws of physics so the benefits you get over more conventional wideband designs are not very great.

Fractal antennas are not dead and indeed a mate of mine from Loughborough university is presenting a paper at an ESA conference on this very subject in just a few weeks time.

According to the current best measurement (Hipparcos), Sirius is 8.60 light years away. (I'm severely nit picking, I know) The rest of your post is exactly correct. There's a good reason that "astronomical" is used as an adjective to mean "so large as to defy comprehension". The distances to objects, even in our solar system, are so great that travel to any of them by any means takes years. Pluto is less than 1/1000 of a light year away. The Voyager 2 mission took 12 years to reach Neptune (which was farther from the Sun than Pluto at the time). At that pace it would take over 100,000 years to reach Sirius. Even allowing for continuous acceleration between the stars, probes will take centuries to reach their destinations.

The Handgrip Dynamometer

(HGD) is a stowable hand held device capable of measuring instantaneous hand strength as a function of time. The principle components of the HGD are a handgrip, instrumentation amplifier, and associated cables. Dynamic voltage representing instantaneous hand strength is taken from the output of the instrumentation amplifier and sent to a laptop computer or to a data acquisition system for data manipulation, display, correlation with other data sources, and/or storage.

Which basically means we get to watch astronauts use a vice grip.

Yes, I know there is valid research going on...I think

There are lots of people here talking how open source won't work for hardware designs since it's so damn a) cost expensive and b) time expensive (does not allow experimenting) to get a chip design through a fab. So what? Reconfigurable hardware is out there and has been for quite some time.

You get a standard programmable logic device from some company like Altera (there are more, this is just the one I remember right now) and then you can program it with any chip design you want (within the complexity boundary set by the chip in question). These can do from 25MHz up to 100MHz, so you won't be able to replace your 1GHz Athlon with it, tough. Still it's usable for a lot of things. Remember, PCI runs at 33MHz or 66MHz. An MP3 decoder can be done with a lot less than 25MHz.

The software (Windows, since the control interface of the PLD is usually proprietary) compiles your Verilog or VHDL code into the required form which can be uploaded into the chip. So hardware can be designed much like software with the same round trip times. And no, you won't have to write an adder using NAND gates, you just say in VHDL "a And once you have a nice working design you can use the same source to get it through a fab.

But often you don't want a fab at all. Fabs are expensive and production has a long latency (something like 4 to 6 weeks). You can just give the PLD a finished ROM and use that as a production system. One MP3 player was only two months on market before being replaced by a successor, so it was shipped with PLDs. Only if you have really large numbers to produce, the product stays long enough on the market or the speed of a PLD isn't enough is a fab really cost efficient. I guess we'll see a lot more PLDs in shipped products in the future.

There are quite a number of CPUs for PLDs available already. Some PLD companies license CPU designs for use with their devices, e.g. I have an Altera APEX device here in front of me (not mine, a bit expensive) which comes with a NIOS softcore. Which is configurable: choose 16 or 32 bit, the number of address bits, how many registers, number of positions the shifter can shift in one cycle, ... depending on how much room you need on the device for your own design (I'm not a hw designer myself (yet), I have to program the NIOS).

Other designs are freely available under open source / free licenses (lots of stuff, not restricted to CPUs), including a SPARC CPU with peripherals by the European Space Agency under LGPL. If your PLD is large enough, you can put a whole computer on that chip (CPU, ROM, RAM, serial port etc.).

And for starters, you can get a complete development board with a PLD and software for about $150. A small CPU (no 32 bit thing with lots of registers) would fit, and it's enough for some hacking to get up to speed.

Some links for open source hardware: OpenCores, Free IP, Google Web Directory - Computers > Hardware > Open Source, LEON-1 (the ESA SPARC core).

Capt. Ron

yes, you're right, it seems i was. i'm glad you responded anyway; you asked some good questions.

i got my data from Helen Caldicott, founder of Physicians for Social Responsibility, regarded by some as an extremist (read: aggressively radical), regarded by others as aggressively logical, regarded by many as an irritant. I could not re-find the original citation, & so was forced to make do with information from the Agency for Toxic Substances and disease Registry. This site does paint a much less grim picture: it states that 1400 pCi/kg body weight causes bone cancer in 4 years. A pCi is equivalent to one-billionth of an mCi; one mCi of plutonium 239 weighs .016 grams. I'm assuming NASA used Pu -239, not Pu -238, which has a much higher toxicity (one mCi weighs .00006 gm). So the upshot is 2.24-8 g/kg body weight is enough to give a person bone cancer in 4 years & therefore .00000152 grams would be carcinogenic to a 150 lb (68kg) person.

nonetheless, that same site lists the Annual Limit on Intake of Pu-239 as 20,000 pCi, which is equivalent to 3.2-7 g, or three millionths of a gram. It does not, however, say what the result of exceeding this limit would be.

Yet NASA's Final Environmental Impact Statement warns of the dangers of "inadvertent reentry," stating that if the Cassini disintegrates, dispersing the plutonium, "5 billion of the estimated 7 to 8 billion world population at the time ... could receive 99 percent or more of the radiation exposure." This condition would necessitate the banning of future agricultural land use and the permanent relocation of the population in any affected urban area.

Originally I had thought that solar power was a viable alternative. Visiting the European Space Research and Technology Centre shows that it is not.

I suppose that now is the time to hang the tie-dyed dancing teddy bears, but it seems to me that if the best safe option is not feasible, perhaps the mission should not be flown at all. The risk of a necessary "permanent relocation" of entire urban areas seems unacceptable to me, especially if we are still theoretically practicing democracy.

As far as the media goes, I think media outlets--especially the conglomerates, or the ones owned by conglomerates--generally hesitate to dig into little-known government scandals, since the government is one of its main sources of information. For instance, a reporter can simply report verbatim what a government agent has said, and feel secure in not verifying it. (I have done the same thing above, perhaps naively).

Civilian reports, on the other hand, require research and verification, which is time-consuming and expensive. Therefore reporters lean towards government sources since it is more expedient and generally puts them in a better light with their bosses, since they don't have to authorize unusual expenditures. Smaller for-profit venues don't have the funds for extensive investigations; not-for-profits are anomalies to be commended.

I do not think this is a conspiracy theory; i think it is simply the result of businesses doing what businesses do, which is attempt to make money. I'm probably safe in saying that media corporations are still corporations, which have as their explicit goal the accumulation of capital.

Here's some rough/bad math on the speed for the halfway point:

Take the distance between Earth and Mars, divided by the time to get there (v=d/s) for the average speed. Assuming 0 starting and ending speed, constant acceleration until the halfway point, and the same acceleration in the opposite direction afterwards, the top speed would probably be about twice the average speed.

Not knowing my astronomy, but looking at some stats, I'll take a rough stab and say the distance would be about 55 x 10^6 km (just for a round number).

So 3 months is 2160 hours. .025 x 10^6 km/h (or 25000 km/h or 15625 mph for those of you in the states) would be your average speed, making your top speed .050 x 10^6 km/h (or 50000 km/h or 31250 mph for the americanos).

So the acceleration would be about 12.9 m/s^2 or roughly 1.3 G.

Now, I'm sure I've miscalculated in there - and I'm not a rocket scientist (ha ha, funny joke) so I'm probably wrong... but 1.3G for continuous acceleration doesn't sound too bad. You'd come back stronger and shorter for the experience... ;)

As you might imagine, the major obstacle to LISA is the expense of the thing. I suspect that the success (or lack thereof) of LIGO will have a big impact on whether LISA ever gets funded. However, all the signals that we know are out there (coalescing neutron stars and the like) are likely to be too weak to detect with LIGO I (only the most optimistic estimates give an appreciable event rate with LIGO I). If LIGO II gets funded, then it will almost certainly see some events, and that could renew interest in LISA. LIGO II isn't scheduled to begin installation until 2004 (assuming it gets funded at all), so I expect we won't see a space-based gravitational wave observatory until sometime after then.

-r

First, the Keck observations are on the net at Titan, with plenty of info on the adaptive optics technology they used to get a better view than Hubble or Voyager I.

Next, visit "The Nine Planets" and their page on Saturn or Titan to get a broad view of what is being researched and who is doing it.

This leads us ot Cassini and the expected observations of Titan. Thanks to the Keck observations, there should be a lot of interest in Cassini's Titan probe. As noted on the Huygens Titan Probe site, on their Why Titan page, the peculiar nature of Titan, with its plentiful organics and opaque atmosphere, have been well known and of great interest since Voyager.

But anyone who wanted to know already knew. So why are we makig a slashdot fuss over mass media coverage of anything scientific?