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SpaceX test flight of Starship SN-5 [video]

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Re: SpaceX test flight of Starship SN-5 [video]

#221

Post by jccooper »

wcoenen wrote: post #162
themgt wrote: post #52

Earlier quoted context omitted.

Yep, and in addition to both of these, Starship is also designed: * to be fueled / ignited such that it can be refueled in-situ on Mars & then launched back to Earth, without advanced rocket fuels or the TEA-TEB chemical igniter. * to be able to refuel from another Starship in-orbit The combination of all of this, if they pull it off, will be the ability to send truly massive payloads to Mars, faster and cheaper than…

> * (or "we can put a couple humans on Mars for 3 days for $100 billion")* Is there actually a NASA proposal like that? As far as I know, orbital dynamics don't allow for this. One has to wait for a Hohmann transfer orbit window to return home.

There is a "short stay" option, where you return on the same synod. This requires a higher-energy transfer, involving Venus on at least one leg, to get there early enough to hit the return window and also have enough time to actually do something on the surface. Apparently you can get up to 90 days in some situations, but 30 is more likely, out of a total elapsed mission time of 400-650 days.

https://nssdc.gsfc.nasa.gov/planetary/mars/marsprof.html

Of course, this in in the "resource-constrained" mode of thinking. If you allow for giant vehicles with on-orbit refilling, SpaceX-style, you just spend a bunch of energy to get there fast instead of monkeying around with Venus.

Re: SpaceX test flight of Starship SN-5 [video]

#222

Post by buzzwordninja »

Jaruzel wrote: post #115

As a child I read all the Tintin books. My favourite ones were Destination Moon, and Explorers on the Moon. The rocket used in those stories is iconic. For me, Starship taps directly into those memories. I know it's infeasible, but if they ever painted the production Starships white and red, it would make me SO happy. I'm too old now (approaching a de-orbit burn for 50) to be able to go to space, but I'm still loving…

One thing I remember from those books is how they lay on their stomach during acceleration, whereas I believe all real life astronauts have been sitting, or on their backs:

http://www.projectrho.com/public_html/rocket/images/deckplan...

Which is also interesting given the recent (well... not even so recent now) discovery of the benefits of placing COVID patients in a prone position to ease breathing.

Re: SpaceX test flight of Starship SN-5 [video]

#223

Post by dwaltrip »

dencodev wrote: post #203
thinkcontext wrote: post #53

Earlier quoted context omitted.

They are testing on a path to be able to land from orbit. Starting with short hops by prototypes that get iteratively improved is the same methodology that allowed them to be able to land their currently operating Falcon 9. They are the only one to ever achieve this. It's a big deal because everyone else builds a $100M rocket and then throws it away because it can't land. Reusable rockets have the potential to make a…

So the idea isn't to literally hop? They ultimately want to land it the same way the F9 rockets land now, and this is just a test?

Yep, basically. The biggest difference is that this is the second stage. With this new rocket, both the first stage and second stage will be fully reusable. The Falcon 9 second stage is thrown away each launch.

Re: SpaceX test flight of Starship SN-5 [video]

#224

Post by throwaway0a5e »

shireboy wrote: post #185
ncmncm wrote: post #158

Earlier quoted context omitted.

To get a sense of the difficulty, imagine sending a million people to the South Pole to set up a self-sustaining colony. That would be much more than 1000 times easier than establishing such a base on Mars.

I’ve often said the same thing. South Pole and underwater cities would be easier than mars or even moon colony. As much as I want the later to happen- I think 1 million people on Mars or Moon will require something that makes them more appealing than even the worst Earth locations. That has to be something pretty drastic. Elon says motivation will be “it’d be cool”. I don’t think that is enough motivation. Still, I’d…

Africa was in Europe's back yard yet when they got the opportunity they colonized the Americas. Colonizing a formerly unexplored place where nobody has yet laid claim has a lot of appeal (and this time we (probably) don't have to kill/displace the natives to do it).

Re: SpaceX test flight of Starship SN-5 [video]

#225

Post by jccooper »

doomlaser wrote: post #29

This is the first time I've seen video of a starship test that didn't end in catastrophic explosion, so this is great news! I'm still worried about the overall design, specifically when it comes to landing. The current procedure is for it to fall into the atmosphere flat on its side, then continue to fall for a long time, and then only when it's near the ground it must reorient 90 degrees to upright and then do a fin…

Good news is, this is next on the test program. They'll be testing the "belly flop" with this vehicle in the next few flights. So they'll see any problems with it before they get too far.

I don't see much reason to be worried about changing orientation in the long term. It's not in a particularly exotic flight regime (subsonic, lower atmosphere) and so long as the vehicle has sufficient control authority (and it will) anything that would cause that maneuver to fail would cause any other maneuver, like landing, to fail as well. The F9 actually already does a (less dramatic) version of this, and has never had a problem in that phase of flight.

Re: SpaceX test flight of Starship SN-5 [video]

#226

Post by valuearb »

QuesnayJr wrote: post #186
themgt wrote: post #52

Earlier quoted context omitted.

Yep, and in addition to both of these, Starship is also designed: * to be fueled / ignited such that it can be refueled in-situ on Mars & then launched back to Earth, without advanced rocket fuels or the TEA-TEB chemical igniter. * to be able to refuel from another Starship in-orbit The combination of all of this, if they pull it off, will be the ability to send truly massive payloads to Mars, faster and cheaper than…

To be fair to NASA, they would never have been allowed to pursue a Starship-like strategy. Look at the Space Shuttle, which had all kinds of requirements ladled on top of the program, such as DoD requirements.

Remember, NASA was the one that added the DOD requirements. To increase their budget, they lobbied congress to cancel the Air Force space program to make it a captive customer of the Shuttle.

Re: SpaceX test flight of Starship SN-5 [video]

#227

Post by paulsutter »

dgritsko wrote: post #208
martythemaniak wrote: post #205

I really love the out-in-the-open development process. It doesn't cost SpaceX anything, yet they attract lots of internet media where people set up streams, discuss progress etc. The next year should be pretty exciting as they develop things further. Starship has a number of big innovations, which are: - the raptor engine. This was developed behind closed doors and is sort of finished. We won't see much of it, but it…

> the most advanced rocket engine ever made Would love to learn more about this, can you expand? What makes Raptor so unique?

In addition to being full-flow, Raptor runs on methane (CH4, the simplest hydrocarbon), which already exists many places in the solar system (including Mars), and is easier to manufacture than kerosene or liquid hydrogen.

SpaceX developed an incredibly advanced simulator to make it happen: https://www.youtube.com/watch?v=vYA0f6R5KAI

Re: SpaceX test flight of Starship SN-5 [video]

#228

Post by TomMarius »

mschuster91 wrote: post #206
TomMarius wrote: post #141

Earlier quoted context omitted.

Was it really shown? Is there a single country that did not replace stress of violence and starvation with economic stress? Do we have at least one larger example of what would happen if the general population was rich?

> Do we have at least one larger example of what would happen if the general population was rich? We have birth rate comparison between "first world" and "third world" countries plus migration experience studies (basically, even one generation after migration from a poor to a rich country, there is a massive drop in birth rate, and after something like 3 generations the birth rate is equal to the rest of the country)…

What country are you talking about? I don't know a single one where the majority does not feel financially stressed with too many children. (usually more than 3, but even 2 is too much for a lot of people, in many countries for the majority, probably including the United States).

Re: SpaceX test flight of Starship SN-5 [video]

#229

Post by valuearb »

jacquesm wrote: post #149
llboston wrote: post #43

Earlier quoted context omitted.

Another significant thing is that Starship is designed to be mass manufactured at a relatively low cost. SpaceX can crank out thousands of Starships, fly them to Mars and build a million people colony. Starship is truly a game changer!

You write that as if it is a done deal. Mars' atmosphere is roughly .5% of that of Earth and almost exclusively CO2. Temperature ranges are well out of what they are on Earth. It is hard for technology to survive there, it is impossible for people to survive there until there has been an unbelievable investment in infrastructure. If you think there will be a million people colony on Mars in your lifetime than you are…

I million people will be very hard.

But the first starship missions will drop 100 tons each to the surface of Mars at a cost of a few hundred million dollars each. And they will send dozens of Starships that first trip, building an camp with over a hundred explorers and scientists the first synod.

They will have thousands of tons of equipment and supplies, and their habitats will have multiple redundancies and be easily repaired.

Mars is far easier to survive on than the Moon, for example. The temperature ranges are far milder, Mars reaches 70 degrees Fahrenheit at its equator during the day. The day is the same length as ours. There is adequate solar for power, tons of water, and a plethora of other easily accessible resources from CO2 to Iron.

Re: SpaceX test flight of Starship SN-5 [video]

#230

Post by ianhorn »

nieksand wrote: post #139
fermienrico wrote: post #65

Can someone please explain the significance of this milestone for a space-ignorant person like myself? I thought SpaceX does these types of landings all the time. :)

SpaceX as a company is trying to solve the "transportation problem" of becoming a spacefaring civilization. Specifically, how do you reduce the cost of access by multiple orders of magnitude? There are three big targets they need to hit: 1. Make Low Earth Orbit (LEO) cheap with a combination of launch cadence and reusability. 2. Reset the rocket equation in LEO by doing in-orbit fuel transfer. 3. Reset the rocket equ…

> 2. Reset the rocket equation in LEO by doing in-orbit fuel transfer.

What do you mean by this? If you want to propel a mass M to delta-v V, you need a certain amount of initial mass. Dividing it into stages is already taken into account. If you split the lower stages into multiple trips, you might change the mass per trip, but you don't change any of the total early-stage mass required, right? Doesn't the rocket equation still apply in exactly the usual way?

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