I'm somewhat confused how having 3 probes all land near each other would improve communication,
The way I understand it, the Beagle2 antenna for communication from ground to orbit is directional, communication works only when the orbiting craft is almost directly overhead. This means that communication is impossible during descent, and also fails if the lander breaks, for instance by landing on a sharp rock, or if the "clam" fails to open, or if it lands on a steep slope or a rock that makes the antenna point the wrong way.
With three landers there is a far higher chance that at least one of them will have a functioning ground-to-orbit antenna.
Indeed, it's imperative that the mission be well designed and tested. No amount of redundancy will help against catastrophic design flaws.
But I read somewhere that among all the Mars lander missions, only one out of three succeeded. I'm guessing that many of them were carefully made, and failed because they encountered unexpected difficulties.
The main cost is design and development. Repeating hardware that has already been designed and developed is far, far cheaper.
Note that the Beagle2 rover was just a small part of the Mars Express spacecraft that went to Mars.
A rover would be great! But it's also more risky, and far more expensive. The Beagle2 system was impressively cheap. With redundancy we could get success at a far lower cost than with a rover.
I do feel that Europe should eventually send rovers, but perhaps not in its first mission landing on Mars. You need to gather experience in increments.
Looking at some technical details (click "Technology"), I get the impression that Beagle2 might be able to crawl over the surface.
The instrument arm is strong enough to lift the instrument package. This strength might be enough to let it push down firmly on the ground, maybe 10 cm away, and then pull itself forward.
Maybe it couldn't pull along all the solar cell parts, maybe it would have to leave them behind, connected through an electric cable.
There's nothing in the description of Beagle2 that suggests that they have thought of this possibility.
They should send three nearly identical copies of the same lander (re-using the same design and development effort), and have them land close enough to communicate directly with each other by radio.
This way, if one lander loses the ability to communicate with the orbiters or with Earth, or even two of them lose it, the third can relay their data. If something goes wrong on a lander, debugging should become far easier if you can still communicate with the broken system.
The scientific instruments could be distributed among them, each carrying roughly a third of the load. This would greatly reduce the size and weight of each lander, and this in turn would simplify the parachute system, the landing system, and many other parts.
Alternatively each lander could have the same weight, with a more varied range of instruments. The Beagle2 systeem is already impressively small and versatile.
Some instruments might be repeated on two landers or on all three, especially some very small and lightweight instruments.
If the landers are small and light enough, all three can travel on the same ship from Earth to Mars. In fact, I think on a single ship you could send several groups with three landers each.
The next step perhaps will be to again turn to computer editing (or maybe just old fashion sketch artists) and take the faces of the children in the photos and get them out ot people in the area, and see if anyone recognises them.
No way. Publicising the face or the identity of victims of sexual abuse is a gross violation of privacy. All the more so when the victim is a child. It becomes renewed abuse. They'll have to use different methods.
And anyways, has anyone solved the challenge-response deadlock problem yet?
He claims to have solved it, but IMO his solution doesn't seem to make much sense. From the article:
Can an endless loop of bounces be created? No. A user of ISACS always sends out email containing a return address with a functional sub-address. Any bounce that is returned (be it from another ISACS account, a traditional Challenge/Response system, or a system with a vacation message) will return to the ISACS enabled account using the valid return address.
Seems to me that spammers can bypass the system simply by re-sending the spam to this valid return address.
The system is impervious to any technical subversion by spammers
Among the questions and answers:
Can an endless loop of bounces be created? No. A user of ISACS always sends out email containing a return address with a functional sub-address. Any bounce that is returned (be it from another ISACS account, a traditional Challenge/Response system, or a system with a vacation message) will return to the ISACS enabled account using the valid return address.
Seems to me that spammers can bypass the system simply by re-sending the spam to this valid return address.
The solution isn't to outlaw the CAPTCHA, the solution is to make additional alternatives available for people who can't "solve" a CAPTCHA. For the blind the solution would be an audio CAPTCHA, and for the very few who are both deaf and blind, a dialogue with a real person, you fill out a form and a dialogue with a real person ensues, you prove that you are a person by answering like a real person. As long as only few users need this personal assistance it should be doable.
Indeed I should have tested by clicking the link. It never occurred to me that Mozilla, of all sites, might block Slashdot references. Every day you learn something new.
this equation is the reason. If v is greater than c, then this equation would require the square root of a negative number.
That may sound convincing to a mathematician, but not to everybody.
To put it another way, the equations also show what amount of energy is spent to accelerate the matter to the speed v. (Energy spent = kinetic energy, see grandparent post.) If you calculate the energy needed to accelerate a body to the speed of light, you find that infinite energy is needed.
You can't even accelerate a speck of dust to the speed of light. Regardless of size and mass, infinite energy would be needed.
Slashdot Mirror
I'm somewhat confused how having 3 probes all land near each other would improve communication,
The way I understand it, the Beagle2 antenna for communication from ground to orbit is directional, communication works only when the orbiting craft is almost directly overhead. This means that communication is impossible during descent, and also fails if the lander breaks, for instance by landing on a sharp rock, or if the "clam" fails to open, or if it lands on a steep slope or a rock that makes the antenna point the wrong way.
With three landers there is a far higher chance that at least one of them will have a functioning ground-to-orbit antenna.
Indeed, it's imperative that the mission be well designed and tested. No amount of redundancy will help against catastrophic design flaws.
But I read somewhere that among all the Mars lander missions, only one out of three succeeded. I'm guessing that many of them were carefully made, and failed because they encountered unexpected difficulties.
The main cost is design and development. Repeating hardware that has already been designed and developed is far, far cheaper.
Note that the Beagle2 rover was just a small part of the Mars Express spacecraft that went to Mars.
A rover would be great! But it's also more risky, and far more expensive. The Beagle2 system was impressively cheap. With redundancy we could get success at a far lower cost than with a rover.
I do feel that Europe should eventually send rovers, but perhaps not in its first mission landing on Mars. You need to gather experience in increments.
Looking at some technical details (click "Technology"), I get the impression that Beagle2 might be able to crawl over the surface.
The instrument arm is strong enough to lift the instrument package. This strength might be enough to let it push down firmly on the ground, maybe 10 cm away, and then pull itself forward.
Maybe it couldn't pull along all the solar cell parts, maybe it would have to leave them behind, connected through an electric cable.
There's nothing in the description of Beagle2 that suggests that they have thought of this possibility.
They should send three nearly identical copies of the same lander (re-using the same design and development effort), and have them land close enough to communicate directly with each other by radio.
This way, if one lander loses the ability to communicate with the orbiters or with Earth, or even two of them lose it, the third can relay their data. If something goes wrong on a lander, debugging should become far easier if you can still communicate with the broken system.
The scientific instruments could be distributed among them, each carrying roughly a third of the load. This would greatly reduce the size and weight of each lander, and this in turn would simplify the parachute system, the landing system, and many other parts.
Alternatively each lander could have the same weight, with a more varied range of instruments. The Beagle2 systeem is already impressively small and versatile.
Some instruments might be repeated on two landers or on all three, especially some very small and lightweight instruments.
If the landers are small and light enough, all three can travel on the same ship from Earth to Mars. In fact, I think on a single ship you could send several groups with three landers each.
Probably used the Gimp.
Impossible! You can't do such shoddy work with Open Source Software.
Oh my god, she'll be recognized!
Simply ask for advice on what to buy for your girlfriend.
Of course you must be prepared to give a size.
Indeed, you're right.
The next step perhaps will be to again turn to computer editing (or maybe just old fashion sketch artists) and take the faces of the children in the photos and get them out ot people in the area, and see if anyone recognises them.
No way. Publicising the face or the identity of victims of sexual abuse is a gross violation of privacy. All the more so when the victim is a child. It becomes renewed abuse. They'll have to use different methods.
You're implying that because of the shoddy editing you can identify the victim by looking at the photos.
I hate to bring you such bad news, but you're seeing things that don't exist.
Sorry to be a semantics pedant, but don't you mean semantics pedant?
We should nuke it anyway, just to be sure.
Don't. The Ramans might object. You don't want to upset the Ramans, as they make three of everything.
The solution isn't to outlaw the CAPTCHA, the solution is to make additional alternatives available for people who can't "solve" a CAPTCHA. For the blind the solution would be an audio CAPTCHA, and for the very few who are both deaf and blind, a dialogue with a real person, you fill out a form and a dialogue with a real person ensues, you prove that you are a person by answering like a real person. As long as only few users need this personal assistance it should be doable.
He said deaf and blind. This means it's for people who neither see nor hear. The deaf-and-blind use braille terminals.
Indeed I should have tested by clicking the link. It never occurred to me that Mozilla, of all sites, might block Slashdot references. Every day you learn something new.
I didn't know. I agree that it isn't useful then.
Thanks for the info, but next time please make your links clickable.
2 7
https://bugzilla.mozilla.org/show_bug.cgi?id=2175
this equation is the reason. If v is greater than c, then this equation would require the square root of a negative number.
That may sound convincing to a mathematician, but not to everybody.
To put it another way, the equations also show what amount of energy is spent to accelerate the matter to the speed v. (Energy spent = kinetic energy, see grandparent post.) If you calculate the energy needed to accelerate a body to the speed of light, you find that infinite energy is needed.
You can't even accelerate a speck of dust to the speed of light. Regardless of size and mass, infinite energy would be needed.
Sad but true.
Almost as rugged as real terminators.
I'm sorry to disappoint you, but those movies were fiction, not factual reports.
"Your car has a tree issue"
A tree issue? Your car has a tree issue?
What's a tree issue? Your car bumps into trees?
Now don't be offended, but that's not a tree issue. It's a driver issue.
Assuming my professor is correct and "optimize" means "adds"
Huh? Optimize means improve as far as possible, make as good as possible.