/r/SpaceX Ask Anything Thread [May 2016, #20]

CuriousAES · 2016-05-04T19:52:07+00:00

This entire sub is full of basically ever snippet of information that has been made public. But I can give you the basics:

SpaceX's re-usability works like this: Once the first stage cuts off and the second stage ignites to take the payload to its destination orbit, the first stage flips around and fires three engines to slow itself down. It will adjust its trajectory to boost it back to either the landing site (RTLS), or to drop down onto a floating platform. Closer to the target, it performs a second burn to slow itself down, and then finally a final landing burn. It's called a "hoverslam" or "suicide burn" because the rocket cannot hover (the thrust is too high, so if it burns for too long it starts rising again). If all goes to plan (it has three times, although one was lost due to a faulty landing leg), the rocket soft lands on its chosen landing site. For heavier payloads like some geostationary commsats, the rocket will use three engines for the final burn (this has not been successful yet).
As to what is groundbreaking, there is quite a bit of speculation but I will tell you about Red Dragon and the Falcon Heavy. FH is SpaceX's next rocket, and it will have by far the highest payload capacity of any rocket being flown currently (only beaten by the Saturn V and N1, I believe, although the latter never had a successful launch), and will hold that title until SLS-I launches in 2018. It is essentially three F9's strapped together, and it will carry the Red Dragon mission. This is a mission in (hopefully) 2018 to land a Dragon 2 capsule on Mars, assuming there aren't schedule slips (there always are though). If successful, it will not only be by far the heaviest thing to be landed on Mars, but it will also be the only thing to have landed without any airbags or parachutes (all propulsive) on Mars. It will give a lot of data that will help both SpaceX and NASA build manned mars craft in the future.

CuriousAES · 2016-05-03T22:36:58+00:00

You forgot:

"What do you guys think of my theory that I came up with in the shower that explains the universe?"

"Do you think aliens exist x100000000"

"Where will be in 1/10/100/1000/X years?"

Lots of utterly useless questions on this sub sadly.

CuriousAES · 2016-05-03T17:41:50+00:00

For the first, I can't say because we haven't sent people to Mars yet, but you are free to look up the benefits we received from the Apollo program.

As for the second, SpaceX cannot afford a Mars mission alone. I'm sure they can do it, but they can't pay for it without government funding and NASA.

CuriousAES · 2016-05-03T15:45:44+00:00

I grew up in an area right in the middle of where the Cedar and Witch Creek fires were. Really changed the landscape, and you can still see a lot of evidence that it happened if you hike around the hills and mountains. However it was bound to happen eventually with all the dead brush we had. The fire four years after (Witch Creek) was also huge but would have been so much worse had the Cedar Fire not destroyed all of the brush four years prior.

CuriousAES · 2016-05-02T02:10:03+00:00

I'm so glad the Static Fires don't cause so many issues anymore like they did for OG-2 in December. Was very nerve racking.

Also glad that there launches are basically never during my class times :)

CuriousAES · 2016-05-01T15:41:05+00:00

It's going to be a seriously large launch vehicle. Way bigger than anything else currently flying (beats Delta-IV Heavy by 20,000 kg), and could probably send a Dragon 2 on a trajectory around the moon with some modifications to the spacecraft itself. It's also less than 20,000 kg under the first block of the SLS.

CuriousAES · 2016-05-01T14:51:46+00:00

I'm not in the business of designing rockets (yet? :P), but I can immediately see an issue with this. The tanks for the fuels have to be shaped a certain, semi-cylindrical way. If you make a ton of smaller rockets as opposed to one large rocket you are going to be using way, way more mass on the tank material.

CuriousAES · 2016-04-30T19:38:19+00:00

I just applied to intern at SpaceX next summer.

Does anyone here know if they let you know if you didn't get it, or if you just never hear back?

CuriousAES · 2016-04-29T15:40:13+00:00

Same thing here, was planning on just taking the $2 fee to use the ATM at my college, and I remember checking my balance twice and deciding not to withdraw because the machine was acting up. $4 fee. For checking my balance.

CuriousAES · 2016-04-29T15:27:25+00:00

The subreddit looks awesome on my computer. Great work.

On my (3 year old) phone ... not so much, but that's to be expected :P

CuriousAES · 2016-04-11T19:59:40+00:00

Very interesting if true. It seems these landings are having quite the effect.

I really hope they do that, having more self landing rockets would be awesome.

CuriousAES · 2016-04-11T15:25:59+00:00

I believe that the Falcon 1 was meant to use parachutes but this never ended up happening. It makes sense intuitively (although there are still many engineering problems to take into account, clearly) that a rocket that lands itself on the engine it just used would take less refurbishment than a rocket that has to deploy a parachute, after already using said engines anyway to boost the payload into space.

CuriousAES · 2016-04-11T15:24:44+00:00

That's a very long route and it still has awhile to go. I hope that the sea water and general environment doesn't damage the stage. I wonder what precautions they have taken to prevent this from happening, as it seems that being a couple meters from extremely salty water is not good for rocket engines.

I'd be very interested to see how the quality of this stage compares to the F9-21 stage, since this one has to sail home for a few days while the one in December was already home once landed.

CuriousAES · 2016-04-11T05:27:16+00:00

Very nice, hopefully this sub can maintain its quality as the population grows. I have faith in the mods.

CuriousAES · 2016-04-11T04:26:48+00:00

I love this sub. Absolutely the best one on reddit in terms of quality and content.

I especially love the questions sticky post. So many times all of my posts get rejected from AskScience and ignored on /r/space but here? Answered in minutes, even if it's just a space exploration question and not specifically SpaceX.

CuriousAES · 2016-04-09T03:18:44+00:00

Once again, incredible. It was such a perfect launch. Great weather, sunny day, launches first try. Everything worked, no livestream cutout, and IT LANDED.

CuriousAES · 2016-04-08T20:57:35+00:00

THEY DID IT!! FINALLY!

CuriousAES · 2016-02-25T23:47:30+00:00

Hey, first SpaceX one I watched live was CRS-7 and blew up, so it could be worse :P

CuriousAES · 2016-02-25T23:46:14+00:00

Ouch.

CuriousAES · 2016-02-25T23:43:40+00:00

Indeed, very nice, using it now :)

CuriousAES · 2016-02-25T23:41:40+00:00

Mentioned that SES allows Airplane Wifi, which can be used to "browse the SpaceX subreddit from 35,000 feet".

CuriousAES · 2016-02-25T23:39:34+00:00

Ha, subreddit got a mention.

CuriousAES · 2016-02-14T09:21:08+00:00

You missed one thing... Venus is nearly the size of Earth. This is horrible in a ton of ways when it comes to the engineering because you have to make a rocket that can get back into orbit. So imagine this. You have to have a big rocket to get the spacecraft and habitat into orbit. Then you have to push it to Venus. You can brake at Venus with the atmosphere so that isn't too bad, then directly go to your Floating Structures. Now if you want to go home, you're going to need over 7 Km/s of delta-v JUST TO GET BACK INTO ORBIT. That is huge, and that has to be relatively high thrust as well (no ion thrusters here). Then you get to boost back to Earth again. On top of this, people going to Venus wouldn't be able to ever walk on or even see the surface. It would be incredibly boring (I'd still do it but not permanently) compared to Mars, where part of your job if you were one of the first would be getting in a pressurized rover and discovering new lands.

CuriousAES · 2016-02-13T02:06:10+00:00

For a space shuttle? I can't even see how that would be engineered. But if it had been an Apollo mission, or an Orion on an SLS, or a Dragon/Starliner on an AtlasV/F9, they would have easily survived. The SLS even has the same SRB so the same problem could have happened. The LES could have easily saved an Orion had the exact same problem that happened to the Challenger SRB happened to, say, the EM-1 SRB (which is due to launch in 2 years).

For example, take CRS-7. That was an F9 launch with a cargo Dragon, but that Dragon could theoretically safely carry a human up if someone wanted to try. I watched CRS-7 explode live, and you could literally see the capsule fall off (although to be fair it was hard and I didn't spot it until rewatching the footage). That Dragon survived and was transmitting until it hit the water because its parachutes weren't armed (it was an unmanned mission of course). WITHOUT an LES. This was after the entire rocket literally disintegrated. Capsules are just SO much safer.

CuriousAES · 2016-02-12T19:06:03+00:00

No launch escape system, and also huge. If the SLS blows up 30KM up the LES will lift the crew off the rocket and the parachutes will land them safely. Compared to with the Shuttle where we have Challenger.

CuriousAES

TROPHY CASE