Become a fan of Slashdot on Facebook

 



Forgot your password?
typodupeerror
×

Comment Re:Futile search? (Score 1) 208

I agree with most of what you wrote. But I have the most interest in sample returns because we have such vastly greater analysis capabilities here on Earth than we could ever send on a mission - especially a lower budget mission. And by leaving off surface science hardware, you save development costs and a significant amount of spacecraft mass.

Also, capturing samples, you don't have to land to have a low impact velocity. If you reach Saturn via ion propulsion then you could at little cost enter a Molniya-like orbit over the plumes so that the spacecraft would be nearly stationary relative to the particles during collection. Enceladus orbits are slow to begin with due to the low gravity (0,114m/s versus Earth's 9,81), and by positioning a high apogee or near-apogee over the plumes it might even be possible to collect jet material at lower impact velocity than one could from the ground. Enceladus's gravity would contribute to decelerating the particles and, if desired, one could have the probe's ascent phase over the plumes (rather than the apogee) for further relative velocity reduction. Impact velocity would be not much more than the random variation between the particles' individual trajectories, and some would impact with near-zero velocity. Combined with a carbon aerogel collector (much less dense than the silica aerogel used by Stardust), I seriously doubt you'd do any damage at all to what's collected - most particles shouldn't even melt.

Every added system is added mass and development cost; landers don't usually come cheap, even on a low-gravity body like Enceladus. And dropping a lander near potentially unpredictable fissure geysers carries a risk. So I personally tend to favor spaceborne collection. That said, one would probably learn more from the surface, and you'd be able to sample surface ices as well, not just plumes.

Comment Re: No it is not (Score 1) 351

>What kinds of products do I need?

And unknown to you, what kind of products you think you need has probably been directly influenced by advertizing. That said, the advertising may not have had the exact effect the company wanted. Long time ago there was a "My that's a spicy meatball" commercial for Alka-Seltzer, the it was a failure for the company, but it drove sales in Italian food. That's how ads stick in your brain and influence what you do.

Comment Re:certified materials (Score 3) 220

You think having the part designed to handle five times the load it actually experienced to not be "with sufficient margin"? How much of a margin do you want them to put, 100x?

RTFA. They were doing statistical-sampling quality control testing of struts. The problem was that most of them were just fine, but there were a very small number which were totally defective and broke at a tiny fraction of their rated value. And no, SpaceX did not make the parts, it was an outside supplier. And yes, SpaceX A) will now be testing 100% of them, and B) is ditching the supplier.

Comment Re:Transparency (Score 1) 220

It's not just about the cost of a failed launch, there's also a huge cost to a company's reputation if a rocket fails. And to their schedule.

Out of curiosity, is there any lightweight way to sense how close a part is to failure *in use*? I mean, finding defects on the ground is great, no question. But what if something would doom a mission not due to a part having a manufacturing defect, but due to an oversight somewhere in the rocket design process, or assembly, or transportation, or launch setup, or unexpected weather conditions, or whatnot? It seems to me it could be a massive boost to launch reliability if one knew that a part was about to fail - for example, in this case, the computers could automatically have throttled back to the rocket to reduce stresses, at the cost of expending more propellant, and possibly been able to salvage the mission. And then the problem could be remedied for future missions, without having to have a launch failure first.

To pick a random, for example, would there potentially be a change in resistance or capacitance or other electrical properties when a strut nears its breaking point?

Obviously, though, if adding sensing hardware would add a high weight or cost penalty, that would be unrealistic.

Comment Re:Futile search? (Score 1) 208

Funny ;) But the main point is that its surface is high radiation and very oxidizing; and as far as we know there's no liquids anywhere on Mars except for possible transients or extremely perchlorate-rich brines (aka, something you'd use to sterilize a rock of life).

On the other hand, subsurface water oceans are common elsewhere in the solar system, and colder bodies are known and/or theorized to have a wide range of alternative liquids.

Comment Re:Holy Jebus (Score 5, Interesting) 220

Also, maybe it's just because I've never worked in that industry before, maybe it's common practice in rocketry, but is anyone else impressed with the use of sound triangulation to figure out which part broke? I've never heard of that being done before.

Sad that the Falcon Heavy won't be launched until next spring, I've been really looking forward to that. Oh well...

Comment Re:Holy Jebus (Score 4, Insightful) 220

Elon is surely really fuming about this one, as I know from past interviews with him that he really doesn't like having to source hardware from outside suppliers. He has the old "robber baron" mindset of wanting to get the whole production chain start-to-finish in house, and it's one of the things that really frustrated him when he started Tesla: at the time of the last interview I read on the subject (something like 3 or 4 years ago), he had gotten SpaceX up to 80% in-house, but Tesla was only up to 20% in-house. Car manufacture has long been all about sourcing parts from a wide range of outside suppliers.

But even at 80% in-house at SpaceX, looks like that remaining 20% still bit them : Seriously, failing at 1/5th the rated failure value? The vendor might as well have given them a cardboard cutout with the word "strut" written on it in sharpie.

Comment Re:Easy trumps security (Score 1) 65

>As long as "easy" takes precedence,

Heck, getting it to work in the first place takes precedence over both. There are so many chunks of code were written in the fashion of "This should work, but it doesn't so I'll do it this wrong insecure fashion. 10 hours of messing around and it still doesn't work in the secure fashion, and gets put on the back burner. A year later someone else looks at the code and the original guy goes "oh crap, I forgot about that".

Comment Re:Futile search? (Score 5, Interesting) 208

The speed of light also comes into play in the Fermi Paradox. It's quite possible that for a billion years there's been a vast galactic scale civilization in the universe emitting copious amounts of readily-identifiable radiation. But if that galaxy is more than a billion light years away, it would be physically impossible for us to see them.

There's lots of things about the universe that would make it hard for advanced lifeforms to spot each other unless they're close.

And I fully agree about our own solar system (although I personally think Mars is a terrible place to look and Europa is overrated). There's so many "worlds" in our solar system with fluids (including water, although I wouldn't be so bold as to say that it's a requirement for all life) and energy sources to harness. Organic chemicals seem very common too, even complex ones.

Of all of the bodies in the solar system, I think Enceladus has the best potential payoff in terms of "dollars vs. chance of finding evidence of life". Namely because you don't even have to land on it to do a sample return (but if you do want to land on it for better sample collection, it takes little energy to take off again). And because it emits its internal sea straight up into space. And its internal sea has interesting properties - namely, it's a hyperbasic sea caused by serpentinization of its rocky core, which is a process that also releases hydrogen, giving a potential fuel source to hydrogen-metabolizing life.

That said, my dream mission is still a Titan sample collection/return mission using an RTG-powered rotary nacelle craft to fly in hops all across the planet over the course of a year, recharging its flight batteries overnight on the surface and taking small samples from every potential terrain - dune fields, rivers, the various seas, cryovolcanoes, etc. It would then re-dock with its ascent stage (single solid stage similar to a small Pegasus stage), lift the ascent stage out of the atmosphere (to reduce drag) and as fast as possible until it's drained its flight batteries (which would happen quickly with the added load), ditch all unneeded weight and fire the ascent stage to re-dock with the ion-powered orbiter that got it there. The orbiter, having spent the past year skimming the outer layers of Titan's atmosphere for return propellant that doubles as an atmospheric sample return, would then return to Earth, possibly skimming Enceladus's plumes and Saturn's atmosphere on the way for more sample returns.

No question that would be a flagship mission, though, requiring two RTGs and three stages. An Enceladus-only return could probably be done on Discovery or New Frontiers budget (probably the latter).

Comment Re:100 million quest to waste 100 million (Score 5, Interesting) 208

It's a serious point. Our own radio signals are probably indistinguishable from background noise from Alpha Centauri, and they're actually reducing with time, not increasing.

Rather than than looking for "stray radio communication" (you really think an advanced society is going to lose lots of energy to stray communications?), we should either be striving for extreme optical / UV resolution (satellite-based interferometer telescope) so that we can spatially resolve surface spectra on extrasolar planets in our area to look for signs of life; and in general look for signs of energy release that might be associated with interstellar travel, such as antimatter annihilation, directed thrust, solar sail reflection, etc.

IMHO.

Comment Re:Too many white and Asian males (Score 1) 398

A better way to understand this would be to look at the demographics of a world college.

Out of 10 applicants

6 would be from Asia
1 would be from Africa
1 would be from Europe
1 would be from North America
1 would be from South America
Australia wouldn't even register on the scale.

You see so many Indians and Chinese in tech because they have universities that teach tech and their are so damn many of them by world population.

Slashdot Top Deals

If all else fails, lower your standards.

Working...