A Big Surprise from the Edge of the Solar System(science.nasa.gov)
science.nasa.gov
A Big Surprise from the Edge of the Solar System
http://science.nasa.gov/science-news/science-at-nasa/2011/09jun_bigsurprise/
75 comments
your "if it's so obvious why didn't they predict it?" question is a result of the way that the article is written which, in turn, is a consequence of the dependency of nasa (and astronomy and space research in general) on public goodwill to motivate funding.
this isn't so exciting, and it isn't so shocking.
it's a standing joke in astronomy / astrophysics that magnetic fields are complicated and misunderstood. whenever something can't be explained it's attributed to tangled magnetic fields. so complexity in the magnetic field - this "foam" - would not be a great shock.
i have a phd in astronomy. one reason i left the field (apart from the small matter of being a pretty crappy astronomer) was that i felt it was a fraud. sure, it wastes much less money than the arms program and, yes, we do have non-stick pans now, but everything you see from the field is presented in a sexed-up, over-sold, exaggerated way to get more funding.
this isn't so exciting, and it isn't so shocking.
it's a standing joke in astronomy / astrophysics that magnetic fields are complicated and misunderstood. whenever something can't be explained it's attributed to tangled magnetic fields. so complexity in the magnetic field - this "foam" - would not be a great shock.
i have a phd in astronomy. one reason i left the field (apart from the small matter of being a pretty crappy astronomer) was that i felt it was a fraud. sure, it wastes much less money than the arms program and, yes, we do have non-stick pans now, but everything you see from the field is presented in a sexed-up, over-sold, exaggerated way to get more funding.
Lately, I've been feeling more of this. I work in numerical simulations of galaxies, and I feel like people are just running simulations and writing papers without bothering to check things like sensitivity to the parametrized recipes for unresolved physics. What really irks me is that when you really do worry about these things, you just look like someone who can't produce compared to these people who are getting jobs without any repercussions from flip-flopping their results every couple of years. Because these simulations can be compared to reality only in very tangential ways, it's like there is no need to worry about being wrong...
Incidentally, did you manage to find a career in a field where things aren't oversold in the pursuit of popular enthusiasm? It seems a fundamental component of capitalism, if not human enterprise in general.
sorry, previous reply mis-understood your question.
this is the same point as the pressure for jobs, really. it's not that astronomy is the only place where things are oversold, or where there's a lot of competition for jobs - it's a question of degree.
in the case of astronomy it doesn't produce much at all of quantifiable physical value. it's not that different to poetry (you can make the same "life-affirming" arguments for both). in contrast, car mechanics, say, do something physically useful: they fix your car and you're willing to pay them for that.
so astronomers and poets are, largely, state funded (through science and arts grants, respectively).
you could, i guess, argue that a car mechanic who places an advert in the local paper is also relying on "over-selling". sure. but i hope you'll agree there's a difference in degree between the two cases: the mechanic is, say, 90% useful, 10% "ephemeral"; astronomy is 99% "ephemeral" [edit: made phrasing less abrasive].
in modern universities, most depts have a range of sources of funding. it's very unusual for astronomy depts to have links with industry because they don't produce anything that people want (there are engineering-related exceptions for optics and detectors). the way they get money is by being cool and hoping to appear attractive to rich donors (or the govt). hence the reliance on "advertising".
ps and to reply directly: yes; i now work on projects that help save people's lives.
this is the same point as the pressure for jobs, really. it's not that astronomy is the only place where things are oversold, or where there's a lot of competition for jobs - it's a question of degree.
in the case of astronomy it doesn't produce much at all of quantifiable physical value. it's not that different to poetry (you can make the same "life-affirming" arguments for both). in contrast, car mechanics, say, do something physically useful: they fix your car and you're willing to pay them for that.
so astronomers and poets are, largely, state funded (through science and arts grants, respectively).
you could, i guess, argue that a car mechanic who places an advert in the local paper is also relying on "over-selling". sure. but i hope you'll agree there's a difference in degree between the two cases: the mechanic is, say, 90% useful, 10% "ephemeral"; astronomy is 99% "ephemeral" [edit: made phrasing less abrasive].
in modern universities, most depts have a range of sources of funding. it's very unusual for astronomy depts to have links with industry because they don't produce anything that people want (there are engineering-related exceptions for optics and detectors). the way they get money is by being cool and hoping to appear attractive to rich donors (or the govt). hence the reliance on "advertising".
ps and to reply directly: yes; i now work on projects that help save people's lives.
Speaking as someone who has also wished at times to make a more immediate, tangible impact on the world around me, I'm glad you're liking your new job. That said, even "ephemeral" things have value. Individuals will buy poetry books, for instance!
You seem to be saying that, since one can't persuade the average person on the street to pay you to write a research paper[1], the research that gets done is "over-sold" through "advertising." In other words, the work is funded not on its own merits, but as a popularity contest. I'd argue, though, even within astrophysics alone, some research is more important than others: maybe it answers more fundamental questions, or could enable a unifying explanatory framework for a broader class of phenomena, or is actually of near-term importance to us on Earth (asteroid location, space weather).
Science is a human endeavor. Yes, there is often hype and trends as people advocate for funding for their next big thing--but there's a lot of that here on Hacker News, too.
You seem to be saying that, since one can't persuade the average person on the street to pay you to write a research paper[1], the research that gets done is "over-sold" through "advertising." In other words, the work is funded not on its own merits, but as a popularity contest. I'd argue, though, even within astrophysics alone, some research is more important than others: maybe it answers more fundamental questions, or could enable a unifying explanatory framework for a broader class of phenomena, or is actually of near-term importance to us on Earth (asteroid location, space weather).
Science is a human endeavor. Yes, there is often hype and trends as people advocate for funding for their next big thing--but there's a lot of that here on Hacker News, too.
I'd argue that astronomy does save lives! It does it through inspiring people to become more educated, and giving them a greater perspective on the nature of our world. Hopefully, that helps limit future conflict, warfare and environmental destruction.
This is probably not as direct as what you do now, though. I am glad you have found something that works better for you :)
This is probably not as direct as what you do now, though. I am glad you have found something that works better for you :)
[deleted]
Wow. Astronomy has always been my dream job so this view is surprising to me. What areas do feel are most exaggerated? Is dark energy a bunch of crap for instance?
EDIT: My last sentences sounds snarky in retrospect...I meant do you feel that something like dark energy is played up.
EDIT: My last sentences sounds snarky in retrospect...I meant do you feel that something like dark energy is played up.
well, my views are probably at one extreme of the spectrum.
dark matter and dark energy are both real problems. my beef isn't with the facts, but how they are presented. for example, i am very skeptical that understanding those will have any major practical consequences (the argument being that they are only significant on astronomical scales - if they were somehow available / useful / practical at human scales then they would be much easier to study). the "poetic" value of "understanding our universe" is something separate, of course.
most astronomers i know (and i know a lot - my partner is a prof at u chile; chile has a lot of telescopes) love what they do. the thing that they dislike most is the extreme pressure for jobs - there are many more grads and postdocs than there are permanent positions. if you're considering a career in astronomy i would weigh that much more than my (cranky) opinions on funding.
(also, you realise that going observing is not sexy? you're sat in a room somewhere, surrounded by computers, with no windows and a bunch of engineers, so tired that you've got mouth ulcers, eating crap food to stay awake as nothing much happens for hours on end. and the meaning of your data won't be clear until you've done a year more of processing and analysis... :o)
ps the most over-sold field currently is planets: very popular; very sexy ("human inhabitable" etc etc); largely pointless. the "dark" problems are at least physics, rather than stamp collecting.
dark matter and dark energy are both real problems. my beef isn't with the facts, but how they are presented. for example, i am very skeptical that understanding those will have any major practical consequences (the argument being that they are only significant on astronomical scales - if they were somehow available / useful / practical at human scales then they would be much easier to study). the "poetic" value of "understanding our universe" is something separate, of course.
most astronomers i know (and i know a lot - my partner is a prof at u chile; chile has a lot of telescopes) love what they do. the thing that they dislike most is the extreme pressure for jobs - there are many more grads and postdocs than there are permanent positions. if you're considering a career in astronomy i would weigh that much more than my (cranky) opinions on funding.
(also, you realise that going observing is not sexy? you're sat in a room somewhere, surrounded by computers, with no windows and a bunch of engineers, so tired that you've got mouth ulcers, eating crap food to stay awake as nothing much happens for hours on end. and the meaning of your data won't be clear until you've done a year more of processing and analysis... :o)
ps the most over-sold field currently is planets: very popular; very sexy ("human inhabitable" etc etc); largely pointless. the "dark" problems are at least physics, rather than stamp collecting.
Astronomy is just a dream of mine since childhood...I'm 38 now and set in my career path more or less. I agree with you that professional astronomy is probably not very sexy. My interest lies in the large scale stuff like quasars, galaxy formation, and the physics underlying neutron stars and black holes. For some reason exoplanets don't do it for me.
Thanks for the reply...it was very interesting.
Thanks for the reply...it was very interesting.
"I'm 38 now and set in my career path more or less"
Fun exercise: Sit down. Think you just died. Like now. Just turn that around in your mind until it sinks in. Watch (hopefully) many of the rationalizations for your choices fall off. Repeat.
Fun exercise: Sit down. Think you just died. Like now. Just turn that around in your mind until it sinks in. Watch (hopefully) many of the rationalizations for your choices fall off. Repeat.
Sorry, that probably sounded defeatist or something. I meant that I am doing something now that I love, and working towards improving my life through this route. I have many dreams, more than a lifetime's worth :P
the thing that they dislike most is the extreme pressure for jobs - there are many more grads and postdocs than there are permanent positions
So its like every other position in academia then? Also like most private sector jobs in a recession/depression. Really having more opening then applicants is a rarity. Engineers, doctors, some other high demand professions, are all a minority in terms of total labor force in the economy.
So its like every other position in academia then? Also like most private sector jobs in a recession/depression. Really having more opening then applicants is a rarity. Engineers, doctors, some other high demand professions, are all a minority in terms of total labor force in the economy.
The situation of astronomers is not comparable to "every other position in academia."
Let's suppose that imbalance between "transitional" positions (grad students, postdocs, visiting researchers/lecturers) and "permanent" positions in Astronomy is the same as, say, Comparative Literature.
The difference is that the astronomers can typically, with just a little deflection, use their quantitative skills to find a different permanent job at reasonable pay. But it's much harder for a comp lit person to do so.
In other words, both astronomers and literature-lovers might have been deluded about job prospects. It's easier for the astronomers to recover, so their situation is not as dire.
Let's suppose that imbalance between "transitional" positions (grad students, postdocs, visiting researchers/lecturers) and "permanent" positions in Astronomy is the same as, say, Comparative Literature.
The difference is that the astronomers can typically, with just a little deflection, use their quantitative skills to find a different permanent job at reasonable pay. But it's much harder for a comp lit person to do so.
In other words, both astronomers and literature-lovers might have been deluded about job prospects. It's easier for the astronomers to recover, so their situation is not as dire.
you can have many applicants per job even with full employment.
my understanding is that astronomy is one of the more competitive areas within academia, but i don't have any figures.
my understanding is that astronomy is one of the more competitive areas within academia, but i don't have any figures.
There was a paper on arXiv a while ago that looked into this, and concluded that while there are enough postdocs to go around, only 25% of postdocs can count on a permanent position. And of course, as time goes on, the number of postdocs keep swelling as people pile up trying to get those jobs...
I'm close to getting out, I've enjoyed my time doing astrophysics but it would probably have been a career-enhancing decision to have done so a while ago...
I'm close to getting out, I've enjoyed my time doing astrophysics but it would probably have been a career-enhancing decision to have done so a while ago...
good luck. if you're anything like me you might be pleasantly surprised at how much less competitive things are in the "real world". the flip side is that typically you do have less freedom.
The sad fact about freedom: In the "real world", you don't have freedom. In academia, you do, but the pressure is such that you never use it...
Do you do any programming? I was curious what problems could be solved by someone who writes code and has a passion for astronomy. I used SDSS data and python to plot high redshift galaxies for a school project. I could clearly see the filaments that make up the large scale structure of the universe. It was a lot of fun and I would like to do similar stuff in the future as a hobby.
sure. you'd be surprised how little maths/physics most software engineers know. so there are lots of jobs out there where knowing that gives you an edge.
my first job after astronomy was working for a company that wrote software used in oil surveys. i worked on the mathematical model for a cable towed behind a boat. the maths was trivial, but only one other person in a company of 30ish could understand it (apparently).
these days i work for a "geophysics consultancy" (a handful of guys who will write pretty much anything you want, usually related to seismic data processing - most fun recent project was using a GPU). but i've also worked on more "normal" software development projects (j2ee once, for example).
to answer your question more directly - most observatories have software engineers on the staff.
my first job after astronomy was working for a company that wrote software used in oil surveys. i worked on the mathematical model for a cable towed behind a boat. the maths was trivial, but only one other person in a company of 30ish could understand it (apparently).
these days i work for a "geophysics consultancy" (a handful of guys who will write pretty much anything you want, usually related to seismic data processing - most fun recent project was using a GPU). but i've also worked on more "normal" software development projects (j2ee once, for example).
to answer your question more directly - most observatories have software engineers on the staff.
"Fraud" is far too strong, to me. Many people are naturally interested in astronomy (when was the last time you saw a HN article about condensed matter physics, or epidemiology?), and popular articles like this provide a short-term return on their investment.
As to the sexing up/over-selling, competition for scarce resources is the very definition of an incentive. The grant funding system has plenty of flaws, but the fact that research is funded through competition a) increases its quality and b) doesn't remove the intrinsic value of its results.
As to the sexing up/over-selling, competition for scarce resources is the very definition of an incentive. The grant funding system has plenty of flaws, but the fact that research is funded through competition a) increases its quality and b) doesn't remove the intrinsic value of its results.
Since you're here, how is this distinct from the 'foaminess' visible in a newtbasin [1], if at all?
1. http://en.wikipedia.org/wiki/Newton_fractal also enormously fun to do with chains of actual magnets
1. http://en.wikipedia.org/wiki/Newton_fractal also enormously fun to do with chains of actual magnets
Upvoted, if only for mentiong Terence McKenna.
That man was such a great thinker and ponderer (not to mention his huge vocabulary!)
Even though I don't agree with him on every idea, boy, do I wish there were more extremely out of the box thinkers like him around. :)
That man was such a great thinker and ponderer (not to mention his huge vocabulary!)
Even though I don't agree with him on every idea, boy, do I wish there were more extremely out of the box thinkers like him around. :)
There's a reason that he was on shows like Art Bell's. Not quite the guy I'd be quoting in a discussion of science.
"Not quite the guy I'd be quoting in a discussion of science."
He didn't really believe in mainstream science though, and the fact that he's actually able to make a really intelligent and often convincing argument for his views is part of what makes him so interesting. He was definitely interested in a lot of fringe stuff as well, but he always has really good explanations for why we should take various things seriously.
Certainly he had a lot of faults, and was needlessly sloppy or overenthusiastic in many cases, but overall he's got to be one of the most intellectually interesting people of the last couple hundred years.
He didn't really believe in mainstream science though, and the fact that he's actually able to make a really intelligent and often convincing argument for his views is part of what makes him so interesting. He was definitely interested in a lot of fringe stuff as well, but he always has really good explanations for why we should take various things seriously.
Certainly he had a lot of faults, and was needlessly sloppy or overenthusiastic in many cases, but overall he's got to be one of the most intellectually interesting people of the last couple hundred years.
> one of the most intellectually interesting people of the last couple hundred years.
So, that would be since about 1800. In science and mathematics, that would put him in competition with Gauss, Einstein, Darwin, Maxwell, Turing. In philosophy: Mill, Marx, Nietzsche, Russell, Wittgenstein. Not to mention harder-to-pigeonhole people like, say, Goethe. You think he belongs in the same list as those guys? Really?
So, that would be since about 1800. In science and mathematics, that would put him in competition with Gauss, Einstein, Darwin, Maxwell, Turing. In philosophy: Mill, Marx, Nietzsche, Russell, Wittgenstein. Not to mention harder-to-pigeonhole people like, say, Goethe. You think he belongs in the same list as those guys? Really?
It wouldn't make sense to compare him to those guys because he mostly didn't come up with big theories of his own. He was just very well read in all of the above and used their ideas combined with science to call bullshit on mainstream ideas, figure out which questions were the most important, and speculate about the nature of the universe and the human condition. (Much like a modern day Socrates.)
Depending on what you give him credit for I do ultimately think he may be able to hold his own with any of the above, not in terms of coming up with novel theories, but in terms of being able to see what's important and set the agenda for humanity for the next 500 years. But again like Socrates (perhaps Plato) he came up with a lot of bullshit too, so it's important not to throw critical thinking out the window.
Depending on what you give him credit for I do ultimately think he may be able to hold his own with any of the above, not in terms of coming up with novel theories, but in terms of being able to see what's important and set the agenda for humanity for the next 500 years. But again like Socrates (perhaps Plato) he came up with a lot of bullshit too, so it's important not to throw critical thinking out the window.
Could you perhaps be more specific? I'm no McKenna expert, but so far as I can tell (1) calling bullshit on mainstream ideas, as such, is commonplace and does little to "set the agenda for humanity for the next 500 years" and (2) McKenna hasn't, in fact, provided any ideas we have any reason to think will stand us in better stead for the next 500 years than, say, the conventional wisdom would.
So would you care to give some examples of what McKenna's said that will "set the agenda of humanity for the next 500 years" and explain your reasons for thinking they'll do so?
(For the avoidance of doubt: (1) I am not claiming that the current conventional wisdom is in fact all we need for the next 500 years, just doubting whether what McKenna has to offer is any better; (2) I am not claiming that McKenna has had no good ideas or insights; perhaps he has, but so probably have any number of stoned undergraduates; what's useful is producing good ideas that can be identified as such and distinguished from the dross.)
So would you care to give some examples of what McKenna's said that will "set the agenda of humanity for the next 500 years" and explain your reasons for thinking they'll do so?
(For the avoidance of doubt: (1) I am not claiming that the current conventional wisdom is in fact all we need for the next 500 years, just doubting whether what McKenna has to offer is any better; (2) I am not claiming that McKenna has had no good ideas or insights; perhaps he has, but so probably have any number of stoned undergraduates; what's useful is producing good ideas that can be identified as such and distinguished from the dross.)
"So would you care to give some examples of what McKenna's said that will 'set the agenda of humanity for the next 500 years' and explain your reasons for thinking they'll do so?"
So it's very difficult to do this because most of the ideas he espouses aren't really his. I think his main contribution was in combining a wide range of ideas into a compelling worldview.
- His ideas about the fragility of scientific knowledge, its dubious epistemology, e.g. the importance of the anomalous.
- His ideas about the unsustainability of consumer civilization
- His ideas about the epistemological implications of DMT and psilocybin, and drugs in general
- His ideas about using drugs to discover new ideas (IIRC in this talk: http://www.matrixmasters.net/salon/?p=328)
- His ideas about the singularity and teleology
- His idea about drugs have shaped human culture over the millennia, and possibly also human evolution.
- His focus on the big questions like who are we, why are we here, where are we going, etc.
- The way he was able to find elements of validity in paradigms that have long been outright discarded such as shamanism, alchemy, various spiritual traditions, etc.
It's unclear what impact McKenna will ultimately have because it's hard to predict how people will react to living in a world that's running out of material resources, a world with 100x as many academic studies as there are now, a world with unimaginable technology and suffering, etc. But based on how things seem to be going, it's really hard to see how science can remain indefinitely divorced from philosophy and the humanities, which is sort of the essence of his worldview.
It's difficult to see him ever getting credit for much because his ideas would definitely need to be cleaned up by others and reformulated before having a wider impact, and so it's unclear how he would be credited since most aren't really his ideas to begin with. But I still think a lot of the many of the things he espoused are going to be increasingly more important in the future than they are today.
So it's very difficult to do this because most of the ideas he espouses aren't really his. I think his main contribution was in combining a wide range of ideas into a compelling worldview.
- His ideas about the fragility of scientific knowledge, its dubious epistemology, e.g. the importance of the anomalous.
- His ideas about the unsustainability of consumer civilization
- His ideas about the epistemological implications of DMT and psilocybin, and drugs in general
- His ideas about using drugs to discover new ideas (IIRC in this talk: http://www.matrixmasters.net/salon/?p=328)
- His ideas about the singularity and teleology
- His idea about drugs have shaped human culture over the millennia, and possibly also human evolution.
- His focus on the big questions like who are we, why are we here, where are we going, etc.
- The way he was able to find elements of validity in paradigms that have long been outright discarded such as shamanism, alchemy, various spiritual traditions, etc.
It's unclear what impact McKenna will ultimately have because it's hard to predict how people will react to living in a world that's running out of material resources, a world with 100x as many academic studies as there are now, a world with unimaginable technology and suffering, etc. But based on how things seem to be going, it's really hard to see how science can remain indefinitely divorced from philosophy and the humanities, which is sort of the essence of his worldview.
It's difficult to see him ever getting credit for much because his ideas would definitely need to be cleaned up by others and reformulated before having a wider impact, and so it's unclear how he would be credited since most aren't really his ideas to begin with. But I still think a lot of the many of the things he espoused are going to be increasingly more important in the future than they are today.
Interesting. All of a sudden a deep space radio telescope seems like a good scientific mission. It would be a fascinating discovery if we poked our noses out of the heliosheath just to discover that all of the missing mass in the universe was to be found in cosmic rays that never reach the inner solar system.
We have good reason to believe that the missing mass cannot be baryonic or fast moving massive particles. This comes from the abundance of elements, so it is indirect but is consistent with other findings.
Furthermore, those cosmic rays would radiate when decelerated. I think if there was substantial mass in cosmic rays, we would see this radiation (did not make a calculation though). Note that the estimate for the mass of dark matter is about ~5 times the normal matter.
Furthermore, those cosmic rays would radiate when decelerated. I think if there was substantial mass in cosmic rays, we would see this radiation (did not make a calculation though). Note that the estimate for the mass of dark matter is about ~5 times the normal matter.
It would be great if we would send one or two such probes out per year, in different directions. We could find so many interesting things. There are currently only two.
You can not do this.
The Voyager probes where only able to escape the solar system because Jupiter, Saturn, Uranus, and Neptune where aligned, and they could use the slingshot effect to accelerate when passing by them. These planets will not be aligned in a similar way until the 22nd century [1][2].
[1] http://en.wikipedia.org/wiki/Planetary_Grand_Tour [2] http://en.wikipedia.org/wiki/Gravity_assist#Limits_to_slings...
The Voyager probes where only able to escape the solar system because Jupiter, Saturn, Uranus, and Neptune where aligned, and they could use the slingshot effect to accelerate when passing by them. These planets will not be aligned in a similar way until the 22nd century [1][2].
[1] http://en.wikipedia.org/wiki/Planetary_Grand_Tour [2] http://en.wikipedia.org/wiki/Gravity_assist#Limits_to_slings...
What about New Horizons[1], launched in 2006? It's supposed to leave the solar system in 2029, according to wikipedia (granted, citation needed).
[1] http://en.wikipedia.org/wiki/New_Horizons#Key_mission_dates
[1] http://en.wikipedia.org/wiki/New_Horizons#Key_mission_dates
It would be especially great if we could send one out of the plane of the ecliptic (i.e. out of the "top" of the sun rather than the "side").
I think the NASA/ESA Ulysses probe did that - it used Jupiter to flip the probe out of the plane of the ecliptic:
http://en.wikipedia.org/wiki/Ulysses_%28spacecraft%29
http://en.wikipedia.org/wiki/Ulysses_%28spacecraft%29
Unfortunately in this case we cannot use the slingshot effect.
Why not? Doesn't gravity work in the Z coordinate?
But seriously - is there a physical reason not to send a probe "over the top" of the sun and fling it up, rather that out?
[Edit] Note to self. Always consult Wikipedia before opening your trap on HN. http://en.wikipedia.org/wiki/Slingshot_effect
But seriously - is there a physical reason not to send a probe "over the top" of the sun and fling it up, rather that out?
[Edit] Note to self. Always consult Wikipedia before opening your trap on HN. http://en.wikipedia.org/wiki/Slingshot_effect
The "slingshot effect" or gravity assist involves a vessel robbing angular momentum from a large body.
If you launch a vessel towards a planet (so that you come near but don't collide with it), then in the reference frame of the planet your vessel will leave with the same velocity going away from the planet as the velocity of your approach. However, since the planet was moving with respect to the Sun, you will have gained or lost velocity with respect to the Sun, depending on whether your space craft approached from behind or in front of the moving planet. Typically in these assist maneuvers, you wait for a large planet to be a bit ahead of the Earth's orbit. You launch towards that planet, and the gravity assist accelerates the space probe. Some of that acceleration will be tangential (mostly useless to you) but some will be radial, increasing your velocity from the Sun.
The Voyager probes took advantage of a once-in-every 180 year planetary alignment, with all of the outer planets mostly aligned. See http://en.wikipedia.org/wiki/File:Voyager_2_path.png for a good illustration. All the outer planets are traveling in a counter clockwise direction, and you can clearly see the outer planets accelerating Voyager 2 tangentially. It should be clear that there will be a radial component to that acceleration as well.
I don't think you can use the Sun in these circumstances; it doesn't have any angular momentum for you to steal.
Incidentally, the discovery of this method is sheer brilliance; without using gravity assists it would have taken prohibitively long and required a prohibitive amount of propellant to reach the outer planets.
If you launch a vessel towards a planet (so that you come near but don't collide with it), then in the reference frame of the planet your vessel will leave with the same velocity going away from the planet as the velocity of your approach. However, since the planet was moving with respect to the Sun, you will have gained or lost velocity with respect to the Sun, depending on whether your space craft approached from behind or in front of the moving planet. Typically in these assist maneuvers, you wait for a large planet to be a bit ahead of the Earth's orbit. You launch towards that planet, and the gravity assist accelerates the space probe. Some of that acceleration will be tangential (mostly useless to you) but some will be radial, increasing your velocity from the Sun.
The Voyager probes took advantage of a once-in-every 180 year planetary alignment, with all of the outer planets mostly aligned. See http://en.wikipedia.org/wiki/File:Voyager_2_path.png for a good illustration. All the outer planets are traveling in a counter clockwise direction, and you can clearly see the outer planets accelerating Voyager 2 tangentially. It should be clear that there will be a radial component to that acceleration as well.
I don't think you can use the Sun in these circumstances; it doesn't have any angular momentum for you to steal.
Incidentally, the discovery of this method is sheer brilliance; without using gravity assists it would have taken prohibitively long and required a prohibitive amount of propellant to reach the outer planets.
A theoretical and probably ridiculous question here, but... does not the probe thus reduce the planetary orbital speed by the same amount (relative to mass, I guess), that it gains?
Momentum is conserved in the system (total momentum of probe and planet is always the same). Momentum = mass x velocity, so yes, the planet will slow down, but it's a ridiculously small amount. Think of shooting airgun pellets at a tank barelling down on you to slow it down, but even less effective.
The tank is powered though... if it were COASTING at me, that'd be closer... ;-)
The slingshot effect lets you add or subtract a fraction of the orbital motion of a planet you closely fly by. The key is that the speed relative to the planet will be the same going in as coming out, however the angle of the trajectory of the spacecraft relative to the planet's orbit can be different. If you want to change the plane of an orbit the slingshot effect can still be worthwhile, since it can help kill some of the speed in the ecliptic plane, but it won't help adding to the speed perpendicular to the ecliptic.
Could you not build up a lot of speed in the ecliptic plane with the slingshot effect, and then use the gravity of a planet or the sun to deflect the orbit perpendicular to the ecliptic? (I mean in practice this maybe be unlikely to be feasible, but in theory it is with the right planet arrangement)
Yup, you can do that, but the faster you go the less you'll be deflected, and you won't get a speed increase as you would with a normal planetary assist.
I suspect the energy requirements to do so would so large as to be impractical.
Maybe, but with a limited budget for probes there's a lot of things I'd rather see than "what empty space looks like, in different directions"
It's not empty! That's what's so fantastic!
Voyager1 and 2 were sent around 30 years back. If we send now, we will get results only after 2040 only.
That's my point exactly. Don't wait. Send probes out every year. Because it takes so long for them to get to these places. A few may get lost on the way. Some instruments may malfunction. So better send out more. What would that cost? Half a billion dollars a year? Probably much less, because construction would get more efficient.
Well, the more reason to launch them now and not wait another year.
I don't think a new one would take 30 years.
http://www.grc.nasa.gov/WWW/ion/overview/overview.htm
It tops out at 90,000 meters per second.
http://voyager.jpl.nasa.gov/mission/interstellar.html
The furthest one out is 17 billion kilometers.
http://www.google.com/search?sourceid=chrome&ie=UTF-8...
http://www.google.com/search?sourceid=chrome&ie=UTF-8...
That's about six years, though I don't know how long it would take to reach the top speed.
http://www.grc.nasa.gov/WWW/ion/overview/overview.htm
It tops out at 90,000 meters per second.
http://voyager.jpl.nasa.gov/mission/interstellar.html
The furthest one out is 17 billion kilometers.
http://www.google.com/search?sourceid=chrome&ie=UTF-8...
http://www.google.com/search?sourceid=chrome&ie=UTF-8...
That's about six years, though I don't know how long it would take to reach the top speed.
How long does it take the data to reach us?
Speed of light, baby! IIRC, on the order of 4 hours from Pluto. 16 hours (one-way) out to Voyager 1 where it is now.
Wolfram Alpha excels in that type of questions:
http://www.wolframalpha.com/input/?i=distance+pluto+%2F+ligh...
http://www.wolframalpha.com/input/?i=distance+voyager+1+%2F+...
P.S. You are correct.
http://www.wolframalpha.com/input/?i=distance+pluto+%2F+ligh...
http://www.wolframalpha.com/input/?i=distance+voyager+1+%2F+...
P.S. You are correct.
http://en.wikipedia.org/wiki/Speed_of_light
"astronomical units per day: 173"
http://en.wikipedia.org/wiki/Astronomical_unit#Examples
"94 AU: Termination shock between Solar winds/Interstellar winds/Interstellar medium"
I think astronomers would prefer data move back and forth faster, but they're used to waiting that long and more for things to happen.
"astronomical units per day: 173"
http://en.wikipedia.org/wiki/Astronomical_unit#Examples
"94 AU: Termination shock between Solar winds/Interstellar winds/Interstellar medium"
I think astronomers would prefer data move back and forth faster, but they're used to waiting that long and more for things to happen.
well you got to think about the future or else voyager 1 and 2 never would been sent out.
they would have just thought "lets not do it because we may not get interesting stuff until 2011"
if something takes time, the smartest thing is to start as quick as possible so you get results that much quicker
they would have just thought "lets not do it because we may not get interesting stuff until 2011"
if something takes time, the smartest thing is to start as quick as possible so you get results that much quicker
This seems like a sort of analog to the way hurricanes sometimes spawn tornadoes. At the boundary where the relatively still external air/space meet the rapidly spinning air/magnetic field generator, you get some turbulent interactions.
I would love to see the equations or programs they're using to model this.
I would love to see the equations or programs they're using to model this.
Is magnetic reconnection an established phenomenon, i.e. verified in a lab or at least strongly theoretically founded?
Apparently it is: http://mrx.pppl.gov/
TL;DR
"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."
"The sun's magnetic field extends all the way to the edge of the solar system," explains Opher. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are now, the folds of the skirt bunch up."
That's just the setup. The point is a little later: "The crowded folds of the skirt reorganize themselves, sometimes explosively, into foamy magnetic bubbles."
I always wondered why those pictures depicted the sun's magnetic field limits as so clean cut from the rest of the galaxy.. didn't seem natural..
Maybe I should have followed my science instincts and perform a career in physics instead of System's Engineering
Maybe I should have followed my science instincts and perform a career in physics instead of System's Engineering
This seems to be the problem with relying solely on the private sector space exploration. With shuttles there is opportunity for revenue, with revenue come investors, with investors we can make progress. However, where is the revenue opportunity from either of these probes? Without a body that can be truly altruistic about projects and the benefit they'll provide, certain projects may never have/or my never again, become a reality.
This kind of news makes me truly excited about the future. We have concrete knowledge about so little in this universe, the future is ripe with possibility if we can just show a little foresight.
This kind of news makes me truly excited about the future. We have concrete knowledge about so little in this universe, the future is ripe with possibility if we can just show a little foresight.
Nobody is proposing relying solely on the private sector for space exploration. But we'll be far better off harnessing market forces to make space access cheap then letting NASA just do the minimum stuff it can do with the suddenly-cheap tools it has access to then we will ever be trying to make the unaccountable jobs-program government space program provide the access. That has demonstrably failed. How many more probes would we have if we cut NASA's budget in half but they could just buy rocket space instead of building and maintaining the Shuttle and ISS at umpty bumbkin billion dollars each?
Watching that video, I couldn't help but wonder what Sheldon Cooper would say. It's unfortunate that NASA needs to work towards this level of public appeal just to try and secure funding.
Could this offer some protection from a gamma ray burst?
Gamma-ray bursts happen all the time, and aren't dangerous to us--the Earth's atmosphere absorbs all of the gamma-rays.
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Correct me if I'm wrong, at that distance isn't it possible to get some unreliable data.
The discovery is huge, but I'm just wondering
The discovery is huge, but I'm just wondering
Boring. With that title, I was expecting a monolith!
Not sure of the validity of the measure/comparison, but it's an interesting idea nonetheless. One does have to wonder though, if it's so obvious now why this phenomenon is happening then why didn't they predict it before seeing the data? Especially if we see the same thing in solar flares. It seems like it's generally a good idea to bet on the laziness of the universe, but beyond that anyone who pretends they know what's going on is probably full of shit.
edit: The Terence McKenna quote is from this talk about his life: http://www.matrixmasters.net/blogs/?p=1509
The talk in general is about his formative intellectual influences, and about why he finds psychedelic drugs to be intellectually interesting. He has another talk that's more about his views of physics, epistemology, and cosmology here: http://www.matrixmasters.net/blogs/?p=297
Perhaps my two all time favorite talks on any subject, albeit you need a high tolerance to ideas that are at times highly speculative. (And sometimes flat out wrong.)