Because Apollo depending on funding that isn't likely to happen now. Once the geopolitical goals were achieved, that money could be better spent other places.
If we want a sustainable program for human expansion into space, things like this will be necessary.
You're misinterpreting how most current spaceflight is done. At present only asteroid/comet/deep space missions use any form of continuous thrust, in the form of low-thrust ion or Hall-effect thrusters. Anything to a major gravitational body will still rely primarily on high-thrust impulses from traditional chemical rocket motors. Though technology on the horizon may be changing that, it is the current state of affairs.
The path to Mars using chemical thrusters is very straightforward -- if you look up the Hohmann transfer, thats basically the way its done. Leave Earth orbit so that your sun centered orbit is elliptical and touches the Mars orbit. When you get to Mars speed up again to catch up (in practice you do a capture burn and do it in a frame where it looks like your slowing down, but nonetheless). If you want to be really clever sometimes you do a major maneuver in the middle to allow you smooth out some of the problems that occur because the planes of the orbits aren't quite the same. All throughout there you do small maneuvers to keep on course. If you want to go faster, you can do faster shorter transfers, but it requires bigger burns on both sides.
However, in order to do this with chemical thrusters, you need a lot of fuel. A 1500 kg probe requires an extra 1100 kg of fuel just for the catching up maneuver, and probably > 3000 kg for the departure burn (I don't have data on that at hand right now). Its logarithmic so if you wanted to get that probe back to Earth you'd have to bump those measures up by factor of 2 or 3. Throw in landing and departing the Martian surface and it just gets uglier. This is why a Mars Sample Return mission is so hard -- you just can't stack that much mass on top of a launch vehicle.
Imagine instead though, that you had a cheap way to get fuel to orbit. 'Space Guns' and other such ideas are primarily ridiculous because they apply 100s of Gs that would kill a person or most hardware. Fuel won't care though -- so use high-cost rockets to get the people and high-value equipment to orbit, fill up empty (expandable?) fuel tanks there with cheap fuel launches, and then get on your way. Maybe ship some more fuel to Mars, but I'm not sure the numbers make sense for that. However, you could definitely use this technology with technology to extract fuel from the Martian environment to make the return leg easier though.
Thats why fuel depots are interesting for space exploration.
I don't think it proves anything yet. The fact that the course is being held despite Congress is encouraging, but nothing is certain until functioning systems have been fully demonstrated.
The other question is what happens when the White House changes hands. Hopefully if some of these options are near finished by then (if its 2012) then it will be hard to radically redirect things again.
Except that SpaceX's advantage isn't their technology. They are standing on the so-called shoulders of giants for their technology.
The innovations that allow them to be cheap are their business and industrial practices. Part of that is being private and having an owner who, while not wanting to lose money, is focused on goals beyond the next quarterly report. Another is being a small company that can pick the best of the best of young unmarried engineers who are salaried and believe enough in the vision of the company to work 80 hours/week with no extra pay. A third part of that is the vertical integration that helps them avoid a lot of the costs inherent to other US suppliers. I'm sure a business person could list a few more, but as an engineer I'm not the most adept in these things.
These are things that can be gleaned from open sources or just talking to a few of their employees. There is little technology to steal, and that that there is could be developed pretty easily. SpaceX's advantage are things that relate to the business environment, the political environment, and the social environment, and won't necessarily translate directly to the Chinese situation.
Considering that the most effective way to do a missile defense system is to target the ascent stage, a single large launch vehicle would be a dreadful idea.
A large LEO platform for delivering weapons is probably not a terribly effective idea either since a space platform is going to be much less hardy than something like a submarine, and we've seen how easy it is to remove an orbital asset. A submarine is effective because they are incredibly survivable and hard to find. Unless you can put the whole thing out of reach of anti-satellite missiles (keeping in mind that if someone builds a GEO-based weapons platform, someone else would build a GEO-capable anti-sat missile), then a boomer with a good crew is far more effective.
A huge rocket does provide a military/geo-political advantage though, but in a fuzzier way. Launch vehicles look like missiles and are based on the same principles, but the specifics are far different. By funneling money into something massive and public like an over-sized rocket, you can demonstrate your technical superiority in a way that implies military superiority, without actually building things that have the potential to destabilize the balance of power. In a soft-power battle for the alignment of smaller states, this is quite valuable. This, not the fictitious public support Apollo enjoyed, is the reason we went to the moon.
I don't think the parent was necessary claiming it was a bad thing, just pointing out that the argument that the number of jobs stays the same is fallacious.
The thing about the broken window fallacy is that if you have someone out breaking windows it *is* good for those directly involved with making windows, its just bad for the economy as a whole.
In this case, it is absolutely true that advancements in technology are making mainstream brick and mortar book retailers obsolete. This will be painful to those who own them, those who work for them, and those who enjoy browsing them. The fallacy is that this is bad for the economy as a whole -- improving efficiency frees up productivity to do more new interesting things, and also might encourage more business for places like coffee shops. However, this shouldn't be taken to mean that transition will be painless. Those buggy whip manufacturers probably had a hard time too.
What are we throwing away? A 40 year old design that never lived up to expectations?
Personally, I think US-based human space flight is looking more interesting than it has in as long as I can remember (I'm 25). We have multiple legitimate hardware designs with estimated deliveries in a 2-5 years. These are low-cost modern designs that take advantage not only of modern technology but also modern manufacturing techniques. They will enable modular missions that can be formulated and executed in that magical 8-year time period, without risking our continued access to LEO.
Reusability has the *potential* to make things cheaper, but its not proven yet.
The shuttle orbiter was re-usable, but the refurbishment process was incredibly expensive. It was also built close to 40 years ago and we've learned a lot since then, so its hard to take it as a valid data point.
SpaceX hasn't demonstrated their re-usability yet. At present, their relative cheapness is based more around vertical integration than reusability right now (and reusing the upper stage is looking less and less likely, but capsule+first stage seems a good start).
And Scaled Composites just isn't in the same league.
This isn't necessarily to disagree or agree, just saying that the jury is still out on that assertion.
I'm not sure I understand why some people here are getting so defensive about it. The article never claims that we should go back to using that test, it is simply presented as a historical curiosity and might invite one to reflect on the standards of today; particularly for me it brings up the balance between the liberal arts and the more vocational paths taken by engineering programs like mine.
I'm not ashamed I can't pass it. Well, I am a little bit, because I fail the Latin sections miserably and took 3 years in high school. Nonetheless, it is fascinating to read though, because it provides a window into the education and mindset of the leaders and high society of the antebellum era.
I've always preferred O'Brien when it comes to Star Trek engineers -- an ordinary family man who is occasionally called on to go above and beyond at times.
Of course Geordi is just a plain old nerd, so there's a lot of identification there.
There and back is a very different proposition than simply going there. I'm certainly aware that we know how to get to Mars. In fact I'm working on a Mars orbiter mission plan right now (I'm a JPL navigation engineer). I worked on a (slightly ridiculous) sample return concept back when I was in undergrad so I have some grasp of what it takes.
There have been studies on sample returns, but nothing really past the proposal stage. Currently it involves multiple vehicles, missions, and funding authorizations. The Falcon Heavy would most likely enable a one-shot sample return, but I'm not one to say certainly on something like that, particularly with the problems finding the funding for that size of flagship mission.
Also, I admit, I had mis-interpreted this as a claim to enabling a manned Mars mission, since thats Elon's stated goal. Those are even less well studied (landing is an ugly prospect) and I'd be concerned about anyone who could say with certainty this would enable that. My mistake -- and I don't mean that sarcastically.
And please, lets keep it reasonable for expected technology development in a 20 year range and consider the obvious feasability constraints. That is, a method that: - doesn't require 100s of Gs (Space guns) - Is only barely theoretically possible with idealized materials (Space elevator)
As someone who works in the industry I'd be happy to get rid of them if you have a reasonable suggestion.
Why do you need something bigger than a Saturn V? Who's to say, smaller vehicles with on-orbit refueling aren't a better approach?
We're at a point now where we really are making real progress. We're moving past the command-and-control approach to exploration taken in Apollo (and proven to fail without extremely high funding levels by the post-Apollo era) and getting to a place where we can do interesting things with sustainable budgets.
The great thing about this concept is that it is not a one-off design. Even if there is only a demand for one of these every three to five years, the fact that it is mostly built from Falcon 9 parts (for which there is a proven market) means that it can be available to be built-to-order without much extra overhead. This is where the big advances in space exploration need to come from right now, not advances in technology, but advances in business and manufacturing practices. We're good at building efficient rockets at this point, but we're not good at keeping them on-time and on-budget.
Because it depends on the engineering of what goes on top of it. The Falcon Heavy wouldn't actually go to Mars, it just has the heft to potentially launch a vehicle that could go there and back again in one shot.
However, since no such vehicles exist or are far enough along in planning to have really believable numbers for mass and capabilities, its hard to say for sure.
Add in that uncertainties in practical engineering for the launch vehicles certainly exist and its a very reasonable statement.
Another handy thing about English units is the ability to divide things by three, or other non-base-10-friendly divisions.
I cant understand why people get so upset about units. Google makes it easy to convert if it really bothers someone. Somehow I use mostly metric at work and imperial units in the rest of my life and survive.
To be clear, it was a not a 3 month operational life. It was a 3-month primary mission.
Primary mission means that the team is in charge of ensuring the success of that to a very high probability. Everyone expects extended missions at this point, and include fuel in the budget (for orbiters, doesn't apply to rovers) for a very long extended missions. However, more risk is allowed in extended mission, allowing reduced costs. I'm currently working the next Mars orbiter, and while our primary mission goes for 1 year, we're planning out the 6 year extended mission as well, and will probably keep flying the thing until it dies.
This isn't to diminish the good work those people did, nor the good luck of having dust cyclones clean the lifetime limiting dust on the solar panels, but the 'operational life' is a bit of a misnomer.
I'm learning the process of doing operations for unmanned spacecraft right now, and some of them are definitely internet accessible.
The reason, at least for what I do, is that we're not always sitting in the control room for operations. For big events, yes, but when you're getting telemetry, processing it, and updating the onboard ephemeris, a cube or office is a lot more comfortable. Furthermore, you need to stay and work from home sometimes, sick child/repairman coming/car broke/whatever, but you still need to get on the flight ops machine and run a maneuver design or upload a file. SSH in and get what you need done.
Not all operations involve sitting in a room on dedicated hardware looking at a screen, and for the more mundane parts, flexibility is wonderful.
As a professional rocket scientist (well navigation engineer) and an amateur IT technician (manage a non-profits web presence), let me tell you: IT is a whole hell of a lot harder.
Of course it may just be that I have a lot more education in one topic than the other.
To be fair, us engineers aren't the best with our statistics sometimes either.
Very few things annoy me (professionally) as much as seeing someone try to apply a Gaussian function to something that is nowhere near normally distributed.
A simple capsule that carries little in the way of extra weight is much more elegant in my mind. Those wings may look nice, but they are heavy and cause trouble.
And who's decided it isn't worth or time? I'm pretty sure NASA's budget is still strong despite the hatchet men in congress, exciting things are happening on many fronts, and we've got *multiple* manned vehicles currently in development and likely to see flight within 5 years. This is an exciting time for space exploration.
As always with this debate, people are trying to debate the means without agreeing on the ends they are trying to achieve.
If you're talking pure science, then manned programs are a waste of time (I may be biased though, I'm a JPLer).
If you want inspiration I think its a toss-up -- the younger generation just has the shuttle which isn't that inspiring. Really, its hard to say. Same with spin-offs, economic impact, and everything else.
However, if you want to see humanity expand beyond our home planet, then the reason to send people to space is to learn how to do it, and to do it better, cheaper, and more safely. As long as you have them out there, science seems a good thing to do. Of course, something economically justifiable and self-sustaining like resource extraction will need to be there to get it beyond anything that are the mere tech demos we have today.
Keep in mind that the attitude of the spacecraft is independent of the trajectory (well, mostly), so what you're seeing are the combinations of attitude changes and and position changes. Without your inner ear telling you which way you're pointing, its difficult to keep your bearings straight.
It seems like on approach its focused on Mimas, which is mostly in the velocity direction, while as it goes through the close flyby it moves to observe Saturn and is pointed in radial direction, and then repoints itself towards Enceladus on the outbound leg, again in the velocity direction. This kind of sequence seems like it would extract the most science from the various encounters.
As far as going through the rings, scale is deceiving and the density is so low the risk of impact was below some mission requirement threshold (probably on the order of 1e-5 or 1e-6).
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Depended, not depending. Sorry.
Because Apollo depending on funding that isn't likely to happen now. Once the geopolitical goals were achieved, that money could be better spent other places.
If we want a sustainable program for human expansion into space, things like this will be necessary.
You're misinterpreting how most current spaceflight is done. At present only asteroid/comet/deep space missions use any form of continuous thrust, in the form of low-thrust ion or Hall-effect thrusters. Anything to a major gravitational body will still rely primarily on high-thrust impulses from traditional chemical rocket motors. Though technology on the horizon may be changing that, it is the current state of affairs.
The path to Mars using chemical thrusters is very straightforward -- if you look up the Hohmann transfer, thats basically the way its done. Leave Earth orbit so that your sun centered orbit is elliptical and touches the Mars orbit. When you get to Mars speed up again to catch up (in practice you do a capture burn and do it in a frame where it looks like your slowing down, but nonetheless). If you want to be really clever sometimes you do a major maneuver in the middle to allow you smooth out some of the problems that occur because the planes of the orbits aren't quite the same. All throughout there you do small maneuvers to keep on course. If you want to go faster, you can do faster shorter transfers, but it requires bigger burns on both sides.
However, in order to do this with chemical thrusters, you need a lot of fuel. A 1500 kg probe requires an extra 1100 kg of fuel just for the catching up maneuver, and probably > 3000 kg for the departure burn (I don't have data on that at hand right now). Its logarithmic so if you wanted to get that probe back to Earth you'd have to bump those measures up by factor of 2 or 3. Throw in landing and departing the Martian surface and it just gets uglier. This is why a Mars Sample Return mission is so hard -- you just can't stack that much mass on top of a launch vehicle.
Imagine instead though, that you had a cheap way to get fuel to orbit. 'Space Guns' and other such ideas are primarily ridiculous because they apply 100s of Gs that would kill a person or most hardware. Fuel won't care though -- so use high-cost rockets to get the people and high-value equipment to orbit, fill up empty (expandable?) fuel tanks there with cheap fuel launches, and then get on your way. Maybe ship some more fuel to Mars, but I'm not sure the numbers make sense for that. However, you could definitely use this technology with technology to extract fuel from the Martian environment to make the return leg easier though.
Thats why fuel depots are interesting for space exploration.
I don't think it proves anything yet. The fact that the course is being held despite Congress is encouraging, but nothing is certain until functioning systems have been fully demonstrated.
The other question is what happens when the White House changes hands. Hopefully if some of these options are near finished by then (if its 2012) then it will be hard to radically redirect things again.
Except that SpaceX's advantage isn't their technology. They are standing on the so-called shoulders of giants for their technology.
The innovations that allow them to be cheap are their business and industrial practices. Part of that is being private and having an owner who, while not wanting to lose money, is focused on goals beyond the next quarterly report. Another is being a small company that can pick the best of the best of young unmarried engineers who are salaried and believe enough in the vision of the company to work 80 hours/week with no extra pay. A third part of that is the vertical integration that helps them avoid a lot of the costs inherent to other US suppliers. I'm sure a business person could list a few more, but as an engineer I'm not the most adept in these things.
These are things that can be gleaned from open sources or just talking to a few of their employees. There is little technology to steal, and that that there is could be developed pretty easily. SpaceX's advantage are things that relate to the business environment, the political environment, and the social environment, and won't necessarily translate directly to the Chinese situation.
Considering that the most effective way to do a missile defense system is to target the ascent stage, a single large launch vehicle would be a dreadful idea.
A large LEO platform for delivering weapons is probably not a terribly effective idea either since a space platform is going to be much less hardy than something like a submarine, and we've seen how easy it is to remove an orbital asset. A submarine is effective because they are incredibly survivable and hard to find. Unless you can put the whole thing out of reach of anti-satellite missiles (keeping in mind that if someone builds a GEO-based weapons platform, someone else would build a GEO-capable anti-sat missile), then a boomer with a good crew is far more effective.
A huge rocket does provide a military/geo-political advantage though, but in a fuzzier way. Launch vehicles look like missiles and are based on the same principles, but the specifics are far different. By funneling money into something massive and public like an over-sized rocket, you can demonstrate your technical superiority in a way that implies military superiority, without actually building things that have the potential to destabilize the balance of power. In a soft-power battle for the alignment of smaller states, this is quite valuable. This, not the fictitious public support Apollo enjoyed, is the reason we went to the moon.
I don't think the parent was necessary claiming it was a bad thing, just pointing out that the argument that the number of jobs stays the same is fallacious.
The thing about the broken window fallacy is that if you have someone out breaking windows it *is* good for those directly involved with making windows, its just bad for the economy as a whole.
In this case, it is absolutely true that advancements in technology are making mainstream brick and mortar book retailers obsolete. This will be painful to those who own them, those who work for them, and those who enjoy browsing them. The fallacy is that this is bad for the economy as a whole -- improving efficiency frees up productivity to do more new interesting things, and also might encourage more business for places like coffee shops. However, this shouldn't be taken to mean that transition will be painless. Those buggy whip manufacturers probably had a hard time too.
What are we throwing away? A 40 year old design that never lived up to expectations?
Personally, I think US-based human space flight is looking more interesting than it has in as long as I can remember (I'm 25). We have multiple legitimate hardware designs with estimated deliveries in a 2-5 years. These are low-cost modern designs that take advantage not only of modern technology but also modern manufacturing techniques. They will enable modular missions that can be formulated and executed in that magical 8-year time period, without risking our continued access to LEO.
I'm excited.
Boeing CST-100, Lockheed Orion, SpaceX Dragon, and Sierra Nevada DreamChaser.
Not only are we replacing it, we're getting multiple options so a catastrophic failure on one doesn't ground us.
Reusability has the *potential* to make things cheaper, but its not proven yet.
The shuttle orbiter was re-usable, but the refurbishment process was incredibly expensive. It was also built close to 40 years ago and we've learned a lot since then, so its hard to take it as a valid data point.
SpaceX hasn't demonstrated their re-usability yet. At present, their relative cheapness is based more around vertical integration than reusability right now (and reusing the upper stage is looking less and less likely, but capsule+first stage seems a good start).
And Scaled Composites just isn't in the same league.
This isn't necessarily to disagree or agree, just saying that the jury is still out on that assertion.
I'm not sure I understand why some people here are getting so defensive about it. The article never claims that we should go back to using that test, it is simply presented as a historical curiosity and might invite one to reflect on the standards of today; particularly for me it brings up the balance between the liberal arts and the more vocational paths taken by engineering programs like mine.
I'm not ashamed I can't pass it. Well, I am a little bit, because I fail the Latin sections miserably and took 3 years in high school. Nonetheless, it is fascinating to read though, because it provides a window into the education and mindset of the leaders and high society of the antebellum era.
I've always preferred O'Brien when it comes to Star Trek engineers -- an ordinary family man who is occasionally called on to go above and beyond at times.
Of course Geordi is just a plain old nerd, so there's a lot of identification there.
There and back is a very different proposition than simply going there. I'm certainly aware that we know how to get to Mars. In fact I'm working on a Mars orbiter mission plan right now (I'm a JPL navigation engineer). I worked on a (slightly ridiculous) sample return concept back when I was in undergrad so I have some grasp of what it takes.
There have been studies on sample returns, but nothing really past the proposal stage. Currently it involves multiple vehicles, missions, and funding authorizations. The Falcon Heavy would most likely enable a one-shot sample return, but I'm not one to say certainly on something like that, particularly with the problems finding the funding for that size of flagship mission.
Also, I admit, I had mis-interpreted this as a claim to enabling a manned Mars mission, since thats Elon's stated goal. Those are even less well studied (landing is an ugly prospect) and I'd be concerned about anyone who could say with certainty this would enable that. My mistake -- and I don't mean that sarcastically.
Got any suggestions?
And please, lets keep it reasonable for expected technology development in a 20 year range and consider the obvious feasability constraints. That is, a method that:
- doesn't require 100s of Gs (Space guns)
- Is only barely theoretically possible with idealized materials (Space elevator)
As someone who works in the industry I'd be happy to get rid of them if you have a reasonable suggestion.
Why do you need something bigger than a Saturn V? Who's to say, smaller vehicles with on-orbit refueling aren't a better approach?
We're at a point now where we really are making real progress. We're moving past the command-and-control approach to exploration taken in Apollo (and proven to fail without extremely high funding levels by the post-Apollo era) and getting to a place where we can do interesting things with sustainable budgets.
The great thing about this concept is that it is not a one-off design. Even if there is only a demand for one of these every three to five years, the fact that it is mostly built from Falcon 9 parts (for which there is a proven market) means that it can be available to be built-to-order without much extra overhead. This is where the big advances in space exploration need to come from right now, not advances in technology, but advances in business and manufacturing practices. We're good at building efficient rockets at this point, but we're not good at keeping them on-time and on-budget.
Because it depends on the engineering of what goes on top of it. The Falcon Heavy wouldn't actually go to Mars, it just has the heft to potentially launch a vehicle that could go there and back again in one shot.
However, since no such vehicles exist or are far enough along in planning to have really believable numbers for mass and capabilities, its hard to say for sure.
Add in that uncertainties in practical engineering for the launch vehicles certainly exist and its a very reasonable statement.
Another handy thing about English units is the ability to divide things by three, or other non-base-10-friendly divisions.
I cant understand why people get so upset about units. Google makes it easy to convert if it really bothers someone. Somehow I use mostly metric at work and imperial units in the rest of my life and survive.
This isn't a security feature, its a standardized opt-out.
Seems like a good thing. Better security to prevent malicious tracking is still important, but its complimentary to this.
To be clear, it was a not a 3 month operational life. It was a 3-month primary mission.
Primary mission means that the team is in charge of ensuring the success of that to a very high probability. Everyone expects extended missions at this point, and include fuel in the budget (for orbiters, doesn't apply to rovers) for a very long extended missions. However, more risk is allowed in extended mission, allowing reduced costs. I'm currently working the next Mars orbiter, and while our primary mission goes for 1 year, we're planning out the 6 year extended mission as well, and will probably keep flying the thing until it dies.
This isn't to diminish the good work those people did, nor the good luck of having dust cyclones clean the lifetime limiting dust on the solar panels, but the 'operational life' is a bit of a misnomer.
I'm learning the process of doing operations for unmanned spacecraft right now, and some of them are definitely internet accessible.
The reason, at least for what I do, is that we're not always sitting in the control room for operations. For big events, yes, but when you're getting telemetry, processing it, and updating the onboard ephemeris, a cube or office is a lot more comfortable. Furthermore, you need to stay and work from home sometimes, sick child/repairman coming/car broke/whatever, but you still need to get on the flight ops machine and run a maneuver design or upload a file. SSH in and get what you need done.
Not all operations involve sitting in a room on dedicated hardware looking at a screen, and for the more mundane parts, flexibility is wonderful.
As a professional rocket scientist (well navigation engineer) and an amateur IT technician (manage a non-profits web presence), let me tell you: IT is a whole hell of a lot harder.
Of course it may just be that I have a lot more education in one topic than the other.
To be fair, us engineers aren't the best with our statistics sometimes either.
Very few things annoy me (professionally) as much as seeing someone try to apply a Gaussian function to something that is nowhere near normally distributed.
A simple capsule that carries little in the way of extra weight is much more elegant in my mind. Those wings may look nice, but they are heavy and cause trouble.
And who's decided it isn't worth or time? I'm pretty sure NASA's budget is still strong despite the hatchet men in congress, exciting things are happening on many fronts, and we've got *multiple* manned vehicles currently in development and likely to see flight within 5 years. This is an exciting time for space exploration.
As always with this debate, people are trying to debate the means without agreeing on the ends they are trying to achieve.
If you're talking pure science, then manned programs are a waste of time (I may be biased though, I'm a JPLer).
If you want inspiration I think its a toss-up -- the younger generation just has the shuttle which isn't that inspiring. Really, its hard to say. Same with spin-offs, economic impact, and everything else.
However, if you want to see humanity expand beyond our home planet, then the reason to send people to space is to learn how to do it, and to do it better, cheaper, and more safely. As long as you have them out there, science seems a good thing to do. Of course, something economically justifiable and self-sustaining like resource extraction will need to be there to get it beyond anything that are the mere tech demos we have today.
Keep in mind that the attitude of the spacecraft is independent of the trajectory (well, mostly), so what you're seeing are the combinations of attitude changes and and position changes. Without your inner ear telling you which way you're pointing, its difficult to keep your bearings straight.
It seems like on approach its focused on Mimas, which is mostly in the velocity direction, while as it goes through the close flyby it moves to observe Saturn and is pointed in radial direction, and then repoints itself towards Enceladus on the outbound leg, again in the velocity direction. This kind of sequence seems like it would extract the most science from the various encounters.
As far as going through the rings, scale is deceiving and the density is so low the risk of impact was below some mission requirement threshold (probably on the order of 1e-5 or 1e-6).