Space Discussion Thread

[AaronT]

It's simply the law of diminishing returns vs design cost.

If you save enough with a reusable rocket to pay for the added fuel and build cost, then it works.

The fact that they abandoned using a reusable second stage at least shows me they are not locked to the concept if it doesn't work.



The Falcon 9 works and is the cheapest way to get something into space. The real question is, how scalable is the concept/tech?

 

[Benm]

I suppose it remains to be seen. Space X is essentially a commercial operation so I suppose they will choose the most economic method. It might take some time to prove if refurbishing landed stages is cheaper than building them from scratch, including the huge loss of potential payload caused by a more robust design and fuel required for a soft landing.

Rocket technology typically scales very well as long as you can practically build it.

Basically if you double a rocket in size (in all dimensions) it will be able to carry 8 times more fuel and oxidizer, but only have 4 times the surface area. The latter is important because many things scale with the surface area, like the outer hull but also fuel and oxygen tanks.

Scaling up basically improves the dry/dead weight to fuel+oxidizer weight ratio making it more efficient.

Another way of shedding dead weight is using multiple stages, though using more stages is costly. Perhaps we will see 3 or 4 stage designs at some point.

 

[NightExplorer96]

Well it's very clear that we cannot attempt space exploration until we find other means of propulsion. Chemical rockets just simply won't cut it to get to Alpha Centauri, much less the other side of the universe

-Alex

 

[Razako]

Chemical rockets won't even get us to Mars effectively. Until we develop an actual effective propulsion method we should probably just focus on issues here on Earth.

I don't know if we'll ever explore other star systems, but it would be nice to at least be able to explore our own with manned missions. Current rocket tech just cannot get it done though. Until something better is developed we should just stick to the robotic probes and rovers.

 

[AaronT]

Chemical rockets won't even get us to Mars effectively. Until we develop an actual effective propulsion method we should probably just focus on issues here on Earth.

I don't know if we'll ever explore other star systems, but it would be nice to at least be able to explore our own with manned missions. Current rocket tech just cannot get it done though. Until something better is developed we should just stick to the robotic probes and rovers.

Some stuff from NASA JPL Eagleworks

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140000851.pdf



There is also 1950s tech that would have done the same thing.

https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)

In fact a NASA team keeps the Orion tech alive because if we ever really needed to divert a NEA then something like Orion is our only real option.

The only major flaw in Orion was the near Earth detonation of the nuclear fuel.

It was proposed that Saturn Vs be used to lob the craft into LEO assemble it.

In the 60s the feasibility study was completed by the DOE and the project was handed to the airforce, who proposed to JFK that we arm it with nuclear weapons and park it over the USSR, JFK was horrified and canceled the development program.



So in short, we have at least the ability to explore our entire heliosphere, with manned spacecraft, in missions that last months not years.

We could make it to a few of the nearest stars and back withing a human lifetime.

It really comes down to the off the shelf option being too dirty, and the "High Tech" option still being mostly just theory.

But, "If we wanted to" we could have a "Nearest Star" craft built and launched within 10 years. We would just have to live with irradiating a relatively small preferably uninhabited bit of the planet to do it.

 

[Benm]

Chemical rockets can clearly deliver stuff to mars, after all that's how those rovers got there. As pointed out before chemical rockets scale pretty well, so we could deliver larger payloads as long as someone is paying to do it.

The latter part could be a big part of the issue. Leading up to the first moon landing the US spent a whopping 3 to 5% of its annual budget on space exploration, in the last decades this has dropped to 0.5% or so.

Right now it seems more feasible that the first man on mars will be there funded by private enterprise. This is not a bad thing, but quite a bit more difficult when you have to stick to budgets set by investors.

If these 'relativistic' drives can be built that could be a game changer, but it all seems very dubious at the moment, mostly because there is no understanding of how they work even if experiments hint they might on a very small scale.

 

[AaronT]

Privately-developed rocket aces abort test ? Spaceflight Now

Blue Origin, the space company founded by Amazon.com’s Jeff Bezos, launched a dramatic flight test over West Texas on Wednesday to verify the performance of an escape system on its reusable suborbital launcher designed to loft space tourists, researchers and commercial astronauts on short rides to the edge of space.

The launcher Blue Origin flew Wednesday has now flown five times, dating back to its maiden launch on Nov. 23, 2015, but this mission was its last.

“What an extraordinary test and a tremendous final flight for both craft,” said Ariane Cornell, a manager on Blue Origin’s strategy and business development team, who provided commentary during the company’s webcast of Wednesday’s flight. “As we very optimistically aimed for, both our crew capsule successfully executed its in-flight escape test, and the booster brilliantly continued to space and came home for a fifth landing on our landing pad just two miles north of where it took off from.”

 

[diachi]

Privately-developed rocket aces abort test ? Spaceflight Now

Blue Origin, the space company founded by Amazon.com’s Jeff Bezos, launched a dramatic flight test over West Texas on Wednesday to verify the performance of an escape system on its reusable suborbital launcher designed to loft space tourists, researchers and commercial astronauts on short rides to the edge of space.

The launcher Blue Origin flew Wednesday has now flown five times, dating back to its maiden launch on Nov. 23, 2015, but this mission was its last.

“What an extraordinary test and a tremendous final flight for both craft,” said Ariane Cornell, a manager on Blue Origin’s strategy and business development team, who provided commentary during the company’s webcast of Wednesday’s flight. “As we very optimistically aimed for, both our crew capsule successfully executed its in-flight escape test, and the booster brilliantly continued to space and came home for a fifth landing on our landing pad just two miles north of where it took off from.”

Saw that yesterday and meant to post it, cool! More progress.

Seems the commercial space companies are stirring up some competition too, which is great!

 

[Benm]

It's a pretty neat demonstration of how you could escape from a launch. This technology might have saved the Challenger space shuttle crew if it were available back then.

If it will actually be required remains to be seen though. Launch vehicles will become more and more reliable, possibly to a point where you don't need an option to bail out anymore.

After all, passenger aircraft aren't usually equipped with parachutes either, though they could be quite useful in some failure modes. Oddly they all carry life vests to survive in water, despite the chance of landing on the open ocean without deadly impact force are slim to none - water is VERY hard when you hit it at 200 mph.

 

[AaronT]

It's a pretty neat demonstration of how you could escape from a launch. This technology might have saved the Challenger space shuttle crew if it were available back then.

If it will actually be required remains to be seen though. Launch vehicles will become more and more reliable, possibly to a point where you don't need an option to bail out anymore.

After all, passenger aircraft aren't usually equipped with parachutes either, though they could be quite useful in some failure modes. Oddly they all carry life vests to survive in water, despite the chance of landing on the open ocean without deadly impact force are slim to none - water is VERY hard when you hit it at 200 mph.

I think the idea is to give "Space Tourists" the warm and fuzzies about going into space.

For serious work (cargo/people not just visiting) it is worth it to shed the weight of the extra safety systems.

 

[Benm]

Possibly, though space is a very hostile environment, a little leak up there will kill you whereas an airplane can do an emergency descent to get some breathable air back in (those oxygen masks only work for 10 minutes or so).

I always find it amusing that they do the life vest safety demonstrations or airplanes, even if the flight is entirely over land and there is zero chance of landing/chrashing on water when you could use one if you magically survived.

One thing i wonder about with this rocket escape system: is it fast enough? It would be fine if your booster somehow failed to provide thrust, but what if it actually explodes suddenly like in challenger?

In the challenger the pod carrying the crew was blown of 'naturally' though the g force from the explosion and low air pressure would probably have knocked them out, otherwise they died when it the ocean.

Oddly they considered fitting the thing with ejection seats of sorts, but the idea was discared because the system was 'safe enough'.

 

[Rivem]

The Blue Origin test was quite impressive. While launch abort systems aren't all that new, doing a launch abort at such a speed is.

Blue Origin's pretty funny though. Jeff Bezos seems to mirror a lot of the stuff Elon's said in the past and tends to make claims ignoring the existence of SpaceX. Their rocket tech is still pretty far behind, but this redeems them a bit.

I just wish we would have a bit more collaboration among the civilian rocketry companies though. Seems like we've got a lot of companies working on stuff in parallel. I think it'd be cool if they came together and invented some standards so that they could at least make somewhat cross-compatible components. It might turn out very valuable for future operators that purchase their equipment.

 

[Benm]

That depends, using a different approach in each company might be helpful in finding the best one overall, possibly better than 'planned' developments like NASA does.

One interesting thing about the commercial companies is their choice of fuel. While NASA mostly flew with cryogenic hydrogen, space x is using RP-1 (basically jetfuel) and blue origin is considering cryogenic methane.

Using cryogenic fuel has pro's and cons. One interesting pro is that you can use the expansion to drive the turbine that drives the fuel and oxidizer pumps, something not uncommon with hydrogen fuelled rockets. I'm not sure if blue origin will do this with methane, but i think it's feasible.

 

[Razako]

Pretty cool IMO. Death of everything by vacuum decay...

 

[NightExplorer96]

^I just saw that video yesterday! Love that YouTube channel

-Alex

 

[Rivem]

That's a good representation of a concept close to the relative edge of modern physics. I think "might be wrong" is a bit of an understatement though. Definitely not something worth worrying about since the Higgs Field was really only recently verified by CERN's research into the Higgs Boson. Naturally, its properties are still very much up in the air.