Space In General

[Dotini]

How many more times must this rocket to barge landing be completed without catastrophic failure before human cargo is carried? Surely one success (out of how many failures?) is not statistical evidence of anything other than happenstance.

 

[TenEightyOne]

How many more times must this rocket to barge landing be completed without catastrophic failure before human cargo is carried? Surely one success (out of how many failures?) is not statistical evidence of anything other than happenstance.

Good question; the engineer would tell you that this landing is proof of the concept at its current point of evolution. The underwriter would say that it's one success from several failures.

 

[wfooshee]

They've landed two, one on land and one on the barge, but they have yet to re-use one. I seem to remember reading that they had no intention of re-using the one they landed a while back on land, but intended to dissect it to learn what they could about how it fared through the process.

 

[eran0004]

How many more times must this rocket to barge landing be completed without catastrophic failure before human cargo is carried? Surely one success (out of how many failures?) is not statistical evidence of anything other than happenstance.

The launch vehicle doesn't carry any cargo when it's landing. The cargo is carried by the spacecraft, which separates from the launch vehicle after the launch.

 

[TenEightyOne]

The launch vehicle doesn't carry any cargo when it's landing. The cargo is carried by the spacecraft, which separates from the launch vehicle after the launch.

The astronauts in Crew Dragon would (hopefully) be making a two-way trip using the same methods that these tests are researching.

 

[eran0004]

The astronauts in Crew Dragon would (hopefully) be making a two-way trip using the same methods that these tests are researching.

Not quite, the Dragon spacecraft comes with parachutes and will be able to land safely without propulsion. The Falcon 9 launch vehicle relies entirely on propulsion. Also, the Falcon 9 is a tall tower that requires careful balancing to not tip over and explode, which won't be a problem with the Dragon.

I'm sure they'll be able to use some of the knowledge from Falcon 9 in the Dragon spacecraft, especially when it comes to guiding the spacecraft to a specific landing site, but the actual landing will be very different, so the failure rate of the launch vehicle doesn't really apply to the spacecraft.

 

[TenEightyOne]

Not quite, the Dragon spacecraft comes with parachutes and will be able to land safely without propulsion.

Yes. That's quite an obvious safety/stand-by feature though, isn't it?

The engines are integrated directly into the sides of the vehicle rather than carried on top of the vehicle as with previous launch abort systems. This configuration provides astronauts escape capability from the launch pad all the way to orbit and allows the spacecraft to use the same thrusters to land propulsively on land at the end of a mission.

So there we have it.

Back to @Dotini's question; "How many more times must this rocket to barge landing be completed without catastrophic failure before human cargo is carried? Surely one success (out of how many failures?) is not statistical evidence of anything other than happenstance".

 

[eran0004]

Yes. That's quite an obvious safety/stand-by feature though, isn't it?

So there we have it.

Back to @Dotini's question; "How many more times must this rocket to barge landing be completed without catastrophic failure before human cargo is carried? Surely one success (out of how many failures?) is not statistical evidence of anything other than happenstance".

And the question is, how many times must the launch vehicle ("this rocket") have to land safely before human cargo is carried. The answer is that the landing of the launch vehicle is totally irrelevant to the safety of the crew, as they would be landing with the spacecraft - not with the launch vehicle.

 

[TenEightyOne]

And the question is, how many times must the launch vehicle ("this rocket") have to land safely before human cargo is carried. The answer is that the landing of the launch vehicle is totally irrelevant to the safety of the crew, as they would be landing with the spacecraft - not with the launch vehicle.

The method used to land Crew Dragon will be identical and will use the same development and evolution. The words "The launch vehicle" were added by you; @Dotini specified "this rocket-to-barge landing" (I added the hyphens to show how the sentence reads in natural English). You can split hairs but the rocket-to-barge landing development is as important for the crewed missions as it is for the cargo missions. Yes, we all know that this was a cargo launcher.

 

[CodeRedR51]

I really don't think there should be a debate on this right now since they haven't even really started testing the landing system for Dragon, which will most certainly require a whole new set of data. What the 1st stage does now really doesn't have an impact on what Dragon will do. They should be treated as two separate things.

 

[eran0004]

The method used to land Crew Dragon will be identical and will use the same development and evolution. The words "The launch vehicle" were added by you; @Dotini specified "this rocket-to-barge landing" (I added the hyphens to show how the sentence reads in natural English).

Because it is a launch vehicle and the distinction between the launch vehicle and the spacecraft is very important to make, in fact there are very few aspects where the two of them can be considered to be even remotely similar.

The methods of landing are similar on an abstract level (basically, they would be both based on propulsion), but since the two vehicles are so different in terms of construction, physical properties, purpose, flight path and optional systems, the application will be very different between the two. Saying that landing the Falcon is identical to landing the Dragon would be like saying that landing the Boeing 747 is identical to landing the Cessna 172. Sure they both use the same concept of landing, but in practice they are two very different things, and the success rate of one vehicle is not applicable to the other.

You can split hairs but the rocket-to-barge landing development is as important for the crewed missions as it is for the cargo missions. Yes, we all know that this was a cargo launcher.

How is the cargo relevant? The launch vehicle doesn't carry any cargo when it's landing. Only the spacecraft does that.

As for splitting hair, does that mean that in your book the Apollo spacecraft and the Saturn V launch vehicle are one and the same thing?

 

[wfooshee]

I read his question as applying to the booster possibly being rated for human flight, and not a question about the Dragon being able to land. In other words, what all do they have to prove and rate to use it with astronauts?

Whether the booster can land is irrelevant to that, i would think. It's more of how safe the booster is in flight. How many blow up while boosting their payload? In that context, one is too many.

Proof of reusablilty would certainly apply to a rating for human flight, were they to try to use previously flown boosters on such missions.

 

[TenEightyOne]

As for splitting hair, does that mean that in your book the Apollo spacecraft and the Saturn V launch vehicle are one and the same thing?

No. They're different things. Parts of Saturn V (Stages II, III) were designed to fly in space though, so they're spacecraft however irrelevant the question. And it's hairs.

You mentioned the launch vehicle and then chased the definitions/differences, nobody else. Dotini simply asked how long before the rocket-to-barge principle was used for humans. Currently the software and methods are used for the never-before-designed function of a self-propelled 25000kg booster landing with rocket motors. Later they'll be doing the same never-before-attempted self-propelled vertical landing project with the 8500kg Crew Dragon component.

The development is relevant even if the primary functions of Falcon 9 and Crew Dragon differ.

To the original question; the Crew Dragon (or subsequent currently-unknown human-occupied derivatives of the project) will be rated to take humans when the technology is proved to have far more hits than misses and when a more-than-satisfactory protocol is in place to identify bad landings before they happen. That's when the parachutes come in

 

[eran0004]

Parts of Saturn V (Stages II, III) were designed to fly in space though, so they're spacecraft

Nope, Saturn V was the launch vehicle of the spacecraft Apollo. Launch vehicles are not considered spacecrafts on their own.

You mentioned the launch vehicle and then chased the definitions/differences, nobody else.

I mentioned the launch vehicle because it is the launch vehicle that is being tested, and it doesn't carry any human cargo when it's landing. The human cargo is carried by the spacecraft. The spacecraft has not been tested yet so we know absolutely nothing about what kind of results they will get when they eventually start with those tests. It's important to keep the differences between the two vehicles in mind. The landings are not identical.

 

[wfooshee]

I imagine the g load on the booster's landing is significantly higher than a manned capsule would use.... that sucker was drilling in to its point, for sure!

 

[CodeRedR51]

They try to get it there as fast as they can because they don't have a whole lot of fuel to use for the landing.

 

[wfooshee]

Exactly what i said in #1799, responding to another user's question.

 

[Swagger897]

landing the Boeing 747 is identical to landing the Cessna 172. Sure they both use the same concept of landing, but in practice they are two very different things, and the success rate of one vehicle is not applicable to the other.

Am I the only one not getting this?

1. Engines:
   1. 747 // Check
   2. 172 // Check
2. Wings:
   1. 747 // Check
   2. 172 // Check
3. Flaps:
   1. 747 // Check
   2. 172 // Check

Am I missing something here?

 

[eran0004]

Am I the only one not getting this?

1. Engines:
   1. 747 // Check
   2. 172 // Check
2. Wings:
   1. 747 // Check
   2. 172 // Check
3. Flaps:
   1. 747 // Check
   2. 172 // Check

Am I missing something here?

Same concept, but in practice it's very different. Ask a Cessna pilot if they'd be comfortable landing a 747...

 

[CodeRedR51]

Back at port. Elon has stated that they hope to have a quick turnaround on this booster and have it ready for launch sometime in June.

 

[Swagger897]

Same concept, but in practice it's very different. Ask a Cessna pilot if they'd be comfortable landing a 747...

Well based on the few landings I've done in a 172, and given the opportunity to fly in Delta's 777, 767, and 737 level D simulators, I'd say there is little to no difference.

 

[BobK]

One rather important difference is that the 747 has a lever that must not be forgotten else landings are kinda screechy and taxiing off the runway becomes difficult. The 172 does not have that lever, unless it's a 172RG.

 

[FoolKiller]

Wouldn't a better comparison be landing a winged craft vs a helicopter? Different shapes, different aerodynamics, different landing speeds, etc.

 

[Robin]

New misson proposal for chip sized spacecraft to travel at record speeds to other star systems. Alpha Centauri in under 30 years, sounds good to me!

www.bbc.co.uk/news/science-environment-36025706

 

[FoolKiller]

My only question is how you keep an Earth-based laser pointing at the exact spot needed for a long period of time. The Earth rotates roughly 15 degrees every hour. That's 1/4 of a degree a minute. That is a huge miss after four light years. The spacecraft will likely need some sort of way to make course adjustments, especially if that sail is affected by solar energy.

 

[CodeRedR51]

CRS-8 first stage landing by SpaceX Photos, on Flickr

High Res landing photos on Flickr.

 

[eran0004]

Well based on the few landings I've done in a 172, and given the opportunity to fly in Delta's 777, 767, and 737 level D simulators, I'd say there is little to no difference.

So you could land a 747 on a 400 meter long grass field?

 

[ProjectWHaT]

The March 9th total solar eclipse looked stunning at the time. But now a team of researchers has put together an even more impressive image of the solar corona...

The picture actually combines two images of the solar corona: The red section was viewed from space, acquired by the Sun-orbiting Solar and Heliospheric Observatory (SOHO) spacecraft, while the blue part was viewed from the ground.

http://gizmodo.com/stunning-solar-eclipse-image-looks-like-the-eye-of-our-1770438041

 

[Swagger897]

So you could land a 747 on a 400 meter long grass field?

Depends on how much of a field is left after the marked runway.

If your point was more centered around purpose rather than practicality, why wouldn't you base your argument around that.

 

[eran0004]

Depends on how much of a field is left after the marked runway.

No it doesn't.