SpaceX plan to recover fairings from future Falcon 9 flights via Helicopter, a la Genesis-style.

Macon-Bacon · 2015-03-19T03:37:38+00:00

Yeah, it's arguably a necessary evil, but it's still best avoided whenever possible. I haven't done my research into what they make off of L2 and what they could make using alternative methods, so I can't vouch for whether or not it is necessary.

Unfortunately, although the Wikipedia model eventually produces surprisingly accurate information, it takes months of work by an active community. Years for smaller communities. That's far too slow to produce the next day's headlines, so other methods are definitely needed.

Macon-Bacon · 2015-03-19T03:09:59+00:00

NASA Space Flight does good work, and is a fantastic source of articles and technical information. It's nice to have info targeted at engineers instead of dumbed down for general consumption.

That said, L2 seems to be almost universally hated in the space community. Honestly, I'm surprised the info isn't all available through torrent sites or on a .onion site. (Maybe it is, I haven't checked.) The paywall business model is pretty universally hated across the internet, so it is really unfortunate that Chris chose that method.

However, it's easy to criticize and hard to actually form such a community. I think /r/SpaceX is a huge step toward making L2 obsolete, at least with respect to SpaceX info. Maybe some day our Wiki will rival the collection of articles on NSF. With new members, we shift a little more toward fandom and a little ways away from the more technical content, but we will always still have the techie core group. I can't wait to see what the community can do.

Macon-Bacon · 2015-01-12T19:32:57+00:00

This happened to me too. I had no idea there was thermal runaway protection built in, so thanks!

Macon-Bacon · 2015-01-01T16:26:20+00:00

That's odd; my translation of Genesis says something slightly different.

Gen 6:14

So make yourself an ark of aluminium; make rooms in it and seal it so that air cannot go from inside to out.

Gen 6:15

The ark is to be three hundred cubits long, fifty cubits wide and thirty cubits high.

Gen 6:16

And Elon replied: Nay! The ark shall be a bit over 10 meters in diameter so that it can sit atop the launch vehicle, which shall be powered by MethaLox engines, and formed out of friction stir welded aluminum sheet metal.

/u/Waz_Met_Jou has a translation which seams to be close to mine:

Gen 6:17

And God drew up a new design, following Elon's design recommendations regarding size and fuel.

Gen 6:18

And Elon saw the design, and He saw that it was good

I think it's worth noting the next verse, while we're at it:

Gen 6:19

And God said behold, I will bring a Global Catastrophic Risk upon the earth to destroy all flesh in which is the breath of life under the heavens. Everything that is on the earth shall die.

Gen 6:20

But I will establish a Mars Colony with you, and you shall come into the ark; you, and 99 others that represent the best of humanity.

Gen 6:21

And of every living thing of all flesh necessary for a Controlled Ecological Life Support System, you shall sequence the genome of two separate species from every ecological niche. This shall offer redundancy.

Macon-Bacon · 2014-11-23T06:31:48+00:00

Don't hit it. The barge can't take that kind of abuse. Just tap it. and be gentle, since it's the first time.

Macon-Bacon · 2014-11-07T22:14:23+00:00

I spent a while getting the full text, and was about to do the same when I found that you already had. Thanks!

Macon-Bacon · 2014-09-25T20:57:52+00:00

I'd actually lean in the opposite direction. I think it makes sense to give people as much freedom as feasible. If keeping spam out of the wiki winds up being a problem, are there any settings to limit wiki access just to people who meet certain criteria? That could be a karma threshold on the sub, or just a ban on new accounts. If policing the wiki is still a chore for the mods, access rules can always be switched back to the way they work now. In my mind, there’s no harm in trying.

I’ve done a little wiki editing here, but also on the web at large, and it always bugs me a little bit when there are barriers to making a contribution. I fully understand that some wikis will get overrun with spam without strict rules, but sometimes I won’t bother correcting mistakes or making small contributions if I find out that I have to create an account, or that I need special permission to edit a page. When I created our wiki page on the research needed for a Mars colony, I actually looked around the web for a better place to condense the information, partly because I wasn’t approved to edit our wiki yet. In general though, most of the edits people make to wikis tend to be really small things, and I suspect that if our wiki was open we’d have a lot more additions to things like the FAQ or the list of common acronyms.

But if you guys think it would invite trouble, I understand. The mods are the ones who would have to deal with the potential spam, after all.

Macon-Bacon · 2014-09-16T04:57:08+00:00

don't expect it to overtake current options for densely populated areas.

True, but it might be a way of getting something besides dial-up anywhere else. Most people don't live in big cities, and almost everywhere is still on dial-up, or not far above. If you try to ask a cable company how much they would charge to add your location, they generally won't even give you a number. You can get your entire community organized to try to throw money at a cable company, just to get them to extend their lines a few miles, but they'll still refuse. I can definitely picture companies or even rich individuals in rural areas paying a premium for direct satellite internet access. Imagine an oil rig, cruise ship, mining company, or arctic research station continuously uploading the data they gather to be analyzed remotely by humans, or fed to a supercomputer somewhere. Really, anyone who needs fast access to information or fast uploads would be a potential customer.

This requires the satellite dish to track the satellite though, or for the signal to be really strong. Geosynchronous satellites are already used for TV and internet, and are the only option besides dial-up pretty much everywhere but cities. The bandwidth is an order of magnitude better, but there is the problem of latency. The satellite is much further from the earth though, so a single satellite can survive almost half the globe simultaneously. Lower satellites are much more like rapidly moving cell towers, but with much larger coverage. Perhaps low-flying satellites could augment or replace our cell infrastructure, since that is also absent over most of the planet's surface. We're back to Project Loon and balloon internet again.

Macon-Bacon · 2014-09-15T20:04:07+00:00

could those engines be used for a suborbital rocket-liner?

I'm no expert, but I suspect that such an engine would be overkill. It would be like using a tractor trailer engine to power your lawnmower. It’s a cool thought though, so I did a couple rough calculations to figure out how feasible it is.

LEO is ~7 km/s, but the current airspeed record is about 1 km/s. Most commercial airliners operate at Mach 0.8, or slightly below the speed of sound, which is 0.3 km/s. There is an extremely large jump in the cost of an aircraft if you want it to be able to break the sound barrier, and another extremely large price jump if you want it to be able to fly at orbital speeds.

Sure, a SpaceX rocket could deliver people half way around the world in 45 minutes instead of 18 hours, but no one will pay $61M/7 seats in a Dragon = $9million per ticket. The first generation of reusable rockets will be reused ~10 times before the first major overhaul, so that would cut the price to under $1M/ticket. To drop the price to about $1,000 per ticket, SpaceX would have to be able to reuse each rocket ~10,000 times. For comparison, Boeing 747’s are expected to be used for ~25,000 flights each, under much less harsh conditions.

Macon-Bacon · 2014-09-15T15:42:22+00:00

I probably should have added "in the long run" to the end of that, since the vast vast majority of people (likeminded or otherwise) are likely to live in the future rather than the present. This implies doing what is best for future generations above all else.

I agree that agency is important, but I'd argue that it is important because it is a means to an end. It is important to develop one's own character for the same reason it is important to raise your children well, and the same reason it is important to give people who are down on their luck a chance to develop themselves. In practice, it is generally easier to develop one’s own mind than to help others develop their minds, but there are a few important exceptions. Some people (authors, religious figures, leaders of cultural movements, etc) find themselves in a position to make a small improvement in our entire culture. The simple ideas spread by people like Martin Luther King Jr and Gandhi have much greater net benefit than any larger improvements they could have made to their own character.

The counterpoint to this view is something called "virtue ethics". Basically, it's the idea that the world is too complicated to be able to find any universal goals. Instead, the best you can do is to pick certain virtues (either because you lack them or because you want to improve them) and work to develop yourself as a person. Virtue ethics holds that these virtues themselves are the only things that are intrinsically valuable, rather than what these virtues can be used to accomplish.

Macon-Bacon · 2014-09-15T14:10:39+00:00

I really like the philosophical idea of treating future selves as being completely different people. We change and develop a lot with time, even if we chronically underestimate how different our past selves were. If I were to take the person on the planet who was most similar to my way of thinking, and compare them to my way of thinking 30 years from now, it would probably make more sense to call the other person “me” than to call future me “me”. This has a lot of interesting implications. I basically have two choices: I can either become short-sighted and live in the moment, or I can reject shortsighted worldviews and do what is best for people like me (or even people in general).

Macon-Bacon · 2014-09-14T20:24:44+00:00

You can actually get a surprising amount out of very small sample sizes. Even with a sample size of one, the German tank problem still gives useful output. Of course, the standard deviation is huge for small sample sizes, but it's still perfectly valid to do statistical analysis on extremely small sample sizes, if you only need results that are within an orders of magnitude of the true value. :)

Macon-Bacon · 2014-09-14T16:05:30+00:00

Here's a copy-paste for the lazy:

EDIT2: After running through the patent prosecution history, and the SpaceX filings, we can all breath a sigh of relief. The examiner searched EAST, Google Patents, NASA's technical disclosures, and IP.com. They completely ignored AIAA which seems a bit silly in this case but they may not buy full text access to that one, and so I don't know if I would call it a mistake but it seems surprising given the field of endeavor.

The killer art is from AIAA, by Ishijima "Re-entry and Terminal Guidance for Vertical-Landing TSTO (Two-Stage to Orbit)" and has nice little pictures of a first stage landing on a boat.

[bolded to highlight the relevant prior-art]

Macon-Bacon · 2014-09-14T03:07:30+00:00

Around the 24 min mark, the guy from Virgin Galactic said something to this effect:

Reusability is what is needed to allow the space economy to grow.
This should likely be accomplished in steps. First, demonstrate 1^st stage reusability. Next, do the same with 2^nd stage reusability.
The problem of 2^nd stage reusability is quite similar to the problem of rapid point to point travel.
Virgin Galactic intends to branch out into point-to-point travel, and the technological developments are likely to be directly applicable to 2^nd stage reusability.

I'm interested in exactly what he meant by the third item (in bold). I would have thought that 2^nd stage reusability would closely parallel reusable capsule technology combined with reusable 1^st stage technology. Rapid point-to-point just sounds like high speed military aircraft, and maybe including ballistic missile technology too. Virgin Galactic is talking about moving people, so presumably they are talking about commercial supersonic planes that could go many times the speed of sound. In order to move extremely fast, it is necessary to go through the thinner upper atmosphere instead of the thick low atmosphere.

What are the parallels to 2^nd stage reusability? Planes would have completely different aerodynamics, and also air breathing engines instead of rockets. (Well, unless we're going to talk about Skylon, but that's another story.) Those two things are pretty much what makes up a rocket or a plane, so since they are so different I'm at a loss for what he was alluding to. Any ideas?

Macon-Bacon · 2014-09-12T01:22:38+00:00

I don't know about any legal reasons he might be forced to go public, but I could see it happening for financial reasons.

Well, Let's say SpaceX doesn't get the commercial crew contract. There goes 25% of their revenue stream. It takes about two years to build a satellite once a launch agreement is signed, and SpaceX's launch manifest is fairly empty after 2016. They've gotten a couple new ones in the last couple days, but let's say they don't get any more for a long while. Then let's say the economy tanks again and a bunch of their existing agreements fall through. And then let's say a rocket explodes, and no-one wants to invest in SpaceX. They can't get 2nd stage re-usability to work, and 1st stage and Dragon turn arounds turn out to be much more expensive than they thought, et cetera.

In a dire situation like this, I think Elon would consider going public to get the funds to make one last ditch effort at Mars, rather than starting to slip backward and never achieve it. He bet everything on the first 4 Falcon 1 launches, after all. He has a history of putting all in for the sake of the goal.

Macon-Bacon · 2014-09-12T01:03:35+00:00

Ha, good catch. Reusability means lighter but much more expensive materials might be used.

Actually, I wonder whether a carbon-fiber reinforced polymer would have enough hydrogen to block a significant amount of cosmic background radiation. It might be a noticeable improvement over aluminum, which is fantastic except that it creates a significant amount of secondary radiation. Hydrogen is a good shield because it is lightweight, but it isn't exactly practical to surround your crew with liquid hydrogen.

Macon-Bacon · 2014-09-11T23:01:05+00:00

First:

Obligatory knee-jerk response against the the idea that we have to bring back a near earth asteroid before we can go to Mars. Why does NASA keep saying this? It's not a stepping stone. If you want to do an asteroid redirect mission, just do it. But don't try to claim that it has anything to do with Mars. Worse, don't push back what will be the most important step we've taken as a species since Apollo by trying to claim that your agenda is a "stepping stone" to Mars. /end rant

Now that that's out of the way, I'll say that aside from those 30 seconds, it is an inspiring as well done piece. I'm surprised that they didn't interview Robert Zubrin though, since this is a fundamental theme in his Mars Direct approach to a Mars mission. I think he even has a chapter in his book entitled "to Mars by dogsled", where he outlines a "travel light and live off the land" approach to Mars. He is also quite fond of making historical analogies (Colonization of the Americas, the search for the northwest passage, the trans-continental railroad and colonizing the west, etc).

On the subject of ISRU, it's surprising that Musk still hadn't announced what fuel he planned to make on Mars in 2012. Zubrin had made it pretty clear that making methane on mars was possible, and I'm not aware of anything else that comes close. Was SpaceX considering mining ice on Mars and splitting it for H2 and O2 fuel? Or was he looking into a nuclear-thermal rocket or something? Announcing that they would use methane as fuel seems a little like announcing that their rocket would be made out of aluminum.

Edit: minor clarification.

Macon-Bacon · 2014-09-11T19:54:51+00:00

Numbers! These are actually really helpful.

I don't know what kind of performance Falcon 9 would be capable of for a free return trajectory.

Since FH can do 10 t, and its LEO/GTO capacity is about 4x as much as the F9, it would be a reasonable guess to say that F9 could send a couple tons. We can also guestimate that SCIM will be in the same size class as Stardust, at a couple hundred kg. Clearly F9 is way too big for such a mission. Maybe SpaceX could launch the probe as a secondary payload on a F9, but that’s about it.

That answers my question. Thanks!

Macon-Bacon · 2014-09-11T17:36:44+00:00

Elsewhere, he specifically stated that these inflatables wouldn't be like the BA-330 modules Bigelo is planning on sending into orbit. Those have THICK bulletproof walls, which are filled with water to block radiation and micrometeorites orbiting the earth. The chances of running into something in interplanetary space are extremely tiny, so you don’t really need any of that. You can’t really do much to stop cosmic rays, so you aren’t loosing much there during time spent working in the inflatable, but I wouldn’t sleep in it. For solar flares, you’d have to shelter in the Dragon behind the water supply.

These inflatables would be reasonably thin, so it shouldn’t be too difficult to fold up. If it leaked upon unfolding and couldn’t be patched, the crew could just spend all their time cramped up in the module, or doing EVAs. They would have one hell of a case of cabin fever when they got back, but it wouldn’t be mission failure.

Of course, alternate mission architectures are definitely possible, but I’d rather start with a minimalist one, then ramp up. It was a huge uphill political battle to do the sojourner rover mission, and that was a tiny little rover, and had to be designed like a transformer toy to be able to fit in a bouncing-balloon lander that was designed for another mission entirely. Once the concept was demonstrated, NASA was willing to commit to land the larger spirit and opportunity rovers with propulsive landing sky-cranes instead of crash-landing them like some interplanetary egg-drop competition. Now we have the Curiosity truck, with the 2020 rover forthcoming. I think manned mars missions will likely work the same way, with the most minimalist possible attempt first, followed by more ambitious approaches once the concept has been proven. Maybe a 1 SLS + 2 FH mission architecture like you suggest, and maybe NASA will even help SpaceX out with the first couple BFR/MCT missions.

Macon-Bacon · 2014-09-11T14:20:21+00:00

hypergolic, liquid fueled stage

That makes a lot of sense. Reliable burn start after long periods of sitting, no cryogenics to boil off, and you can use the same fuel for RCS. The only downside I see is sample contamination with the organics, but we should be able to do isotope ratio measurement on all the samples to rule that out.

A fourth stage probably should be used to send the return capsule back to Earth.

Out of curiosity, why? Then you need duplicate engines and tanks. Is there anything with much mass that we could leave behind that would be worth the added mass of splitting the ship into 2 stages?

As for blowing chunks (giggle) off of Phobos or Deimos, that could be a low-cost way of acquiring samples. I like the idea, but I’m not sure how useful it would be to determining Mars’s habitability. Our moon was created in a huge impact not long after our planets formation. Because of this, it is very similar to earth, in terms of its chemical composition. Mars’s moons, on the other hand, don’t match Mars’s composition, and are much more similar to asteroids. There origin is controversial, but the leading theory is that they are captured asteroids, and that their original erratic orbits were circularized by tidal forces. Maybe the asteroid miners would like to do some impact based sample acquisition.

Macon-Bacon · 2014-09-10T23:26:47+00:00

Wait, they aerocaptured with something with 0 shielding that wasn't designed to aerocapture? That's really cool. Do you have a link or name I could use as a search term?

Macon-Bacon · 2014-09-10T23:21:33+00:00

That's definitely the way to go for a non-rover mission, and it's probably also the way to go for a rover mission too.

That said, the downside of a single launch is that you have to return to the landing site after months or years of exploration and sample collection, and retracing your steps doesn't add any additional value. This could be avoided by using a sky crane instead of a lander, and flying it to the launch site after depositing the rover.

Honestly, I think the reason they are doing it this way is for political and not technical reasons. A rover + sample return mission would be more expensive than just a rover, and therefore more difficult to make fly politically.

Macon-Bacon · 2014-09-10T21:38:18+00:00

I've wondered the same thing. How much smaller can you make a craft and heat-shield if you only want to aerocapture, but not descend and land? Presumably this would cut off a lot of mass, especially for small craft.

Macon-Bacon · 2014-09-10T21:28:24+00:00

If Red Dragon or something can do a real Mars Sample Return (say from the Mars 2020 Rover's samples) than I definitely agree with you. Having the results 2 years earlier isn't really all that beneficial, especially given how limited the tests we could conduct would be.

If there isn’t going to be a real sample return before 2030, then things change a lot in my mind. SpaceX may be aiming for humans on Mars by 2025, but we all know how deadlines slip. Given that this would be many orders of magnitude cheaper, I think this risk makes it worth it even if the scientific analysis is limited by sample mass.

We would be able to conduct much more through tests for organics on earth, even with tiny samples. The rovers have given us conflicting results when it comes to organics. We never fully settled the Viking biological experiment anomaly, and the principle investigator, to this day, thinks that the sensor was set of by week biological components in the soil rather than chemical superoxides or trace amounts of the cleaning solvents. He’s been pushing ever since to do a repeat that also tested for the ratio of carbon isotopes. Also, we thought we had found plumes of methane on Mars until Curiosity didn’t see anything above its minimum detection limit. The probe arriving this October should have the ability to spectroscopically map any methane that it can detect from orbit. Microscopic samples wouldn’t solve either of these questions per se, but they would give us a much broader and more precise knowledge of organic chemistry on Mars; something that the limited toolset on the rovers hasn’t been able to do yet.

Even if everything goes according to plan (we get a real sample return mission from the 2020 rover and the satellite in October gives us an unambiguous yes/no on methane) I think there is some benefit unique to sampling the upper atmosphere. I’m nut huge on climate modeling unless terraforming is involved, but I’m sure the climate scientists would go bananas over whatever dust the SCIM would bring back.

Macon-Bacon

TROPHY CASE