SpaceX: First stage landed Satellites in orbit

[mfb]

The unmanned Dragon can return 3 tons of payload, the planned Dragon 2 will have a similar capacity and can carry up to 7 astronauts up and down (not sure if they are included in the payload mass). Most things don't need to get back to Earth in a controlled way, mainly humans and a few experiment samples, and the Dragon is supposed to be re-usable as well.

Stowed wings need not be heat shielded nor withstand high mach numbers nor drag the vehicle air frame on ascent, so weight comes down.

An additional stowing system adds mass - you still need the wings with their structural integrity to survive re-entry, but now they also have to be retractable for the launch.

 

[mheslep]

...

An additional stowing system adds mass - you still need the wings with their structural integrity to survive re-entry, but now they also have to be retractable for the launch.

I'm thinking wings deploy at 20 to 30 thousand feet on descent. Before that a shuttle shape with no wings does rentry, with wings stowed in an area not exposed to hot gasses, like the top of the shuttle.

 

[mheslep]

The unmanned Dragon can return 3 tons of payload, the planned Dragon 2 will have a similar capacity and can carry up to 7 astronauts up and down (not sure if they are included in the payload mass). Most things don't need to get back to Earth in a controlled way, mainly humans and a few experiment samples, and the Dragon is supposed to be re-usable as well.
.

Shuttle payload return was 14 tons per wiki.

 

[HyperTechno]

nothing yet comes close to the Shuttle's capacity for returning heavy payload to the surface

Yep I agree with you. that was the greatest advantage of shuttles that you can not only send but also return payloads... and the dragon can't handle such an amount of load...
Space shuttles were problematic and were more expensive than traditional Rockets but yet advantageous in some ways...
What I think is it's better to develop a less expensive and effective shuttle project with the modern technology and I guess that's something the modern technology can do...
as with all the shuttle missions the profs and cons of shuttles are well known and what is needed is to come over the cons and develop the profs and I know it's not easy as saying but will worth giving it a try...

 

[HyperTechno]

Just an idea... What about making a shuttle(like thing) without wings and using parachutes in stages to slow it down...(in a way that it stays horizontally in landing)
Landing...mmmmmm... to ocean?. { a safe landing like the returning module of Rockets}

To make it lite

 

[mfb]

Just an idea... What about making a shuttle(like thing) without wings and using parachutes in stages to slow it down...(in a way that it stays horizontally in landing)
Landing...mmmmmm... to ocean?. { a safe landing like the returning module of Rockets}

To make it lite

That's the Dragon capsule approach. But with the additional feature of landing on land.

Shuttle payload return was 14 tons per wiki.

And what was used? Also per Wiki:

The orbiter also recovered satellites and other payloads (e.g., from the ISS) from orbit and returned them to Earth, though its use in this capacity was rare.

 

[cjl]

While the Falcon Heavy and other vehicles will no doubt replace the shuttle's lift capacity, nothing yet comes close to the Shuttle's capacity for returning heavy payload to the surface: seven astronauts and all of their life support which can be reused, plus a few satellites in the trunk.

True, but I don't really consider payload return capability to be terribly important. Look at how often we actually brought something back compared to how often the shuttle was flown - it simply was never a capability that proved particularly useful.

 

[Monsterboy]

True, but I don't really consider payload return capability to be terribly important. Look at how often we actually brought something back compared to how often the shuttle was flown - it simply was never a capability that proved particularly useful.

It will turn out to be useful for long duration manned spaceflights right ? considering that one the main long term goals of SpaceX is to take people to Mars and back.

 

[mfb]

Why? You have to take the crew back - the Dragon V2 can do that. You probably want to return some samples with a manned mission to mars, but a few tons of payload should be more than sufficient for that. Getting the stuff from Mars surface to Earth orbit is the limiting factor, not getting it down to the surface.

 

[HyperTechno]

That's the Dragon capsule approach. But with the additional feature of landing on land.

Well I know that Dragon Capsule has the ability to land on land...
But is it big enough , to do everything the old shuttle could do?

 

[mfb]

It cannot do some thing the old shuttle could (getting heavy/large things back to Earth), but those things are not needed anyway.

 

[mrspeedybob]

I haven't seen any discussion about an obvious application of this technology for a Mars mission. That being, some sort of large rocket will be needed, on Mars, to get our people off of Mars and on their way home. The ability to land a large rocket in a condition which is almost immediately re-usable seems like a prerequisite accomplishment for the Mars mission.
How much of the technology developed to land the first stage of the Falcon form sub-orbital altitude and velocity on Earth, will be applicable to landing a complete, and fully fueled, and ready to use rocket on Mars from Martian orbit?

 

[cjl]

It will turn out to be useful for long duration manned spaceflights right ? considering that one the main long term goals of SpaceX is to take people to Mars and back.

In what way would that be needed for long duration spaceflight? I don't really see why you would need to bring back anything more than just the people and maybe a few samples or something, and a capsule works fine for that.

 

[mheslep]

And what was used? Also per Wiki:

True, but I don't really consider payload return capability to be terribly important. Look at how often we actually brought something back compared to how often the shuttle was flown - it simply was never a capability that proved particularly useful.

Agreed. I think though that to a degree the ISS made that possible, reduced the need for a large return vehicle, as a long term in orbit staging and storage point with full habitation capability. If in the future the ISS was abandoned, then the Shuttle's heavy return and in orbit dwell time might prove tricky to break up into multiple packages and multiple Dragon launches.

 

[cjl]

Agreed. I think though that to a degree the ISS made that possible, reduced the need for a large return vehicle, as a long term in orbit staging and storage point with full habitation capability. If in the future the ISS was abandoned, then the Shuttle's heavy return and in orbit dwell time might prove tricky to break up into multiple packages and multiple Dragon launches.

I'm still not seeing what you're trying to say here - what, specifically, would need to be brought back down?

 

[enorbet]

Re: Travel to Mars - A great deal to do with the viability of a return capsule has to do with velocity affecting the duration of the return trip. While it is possible that 2 months might vaguely be doable with the right people, 6 months is very likely to be intolerable. It was only 7 months ago that SpaceX was certified for Category 2 launches by NASA and while the new agreement with USAF(preview here http://www.spacex.com/news/2015/01/23/united-states-and-spacex-agree-settlement ) shows excellent progress, it may be a year or more before SpaceX has scaled up for increased size and function as well as the track record to be certified for Category 3. I'm willing to bet that SpaceX in general and even Elon Musk personally are keeping an eye on developments in many areas such as VASIMR to improve transit time and alter requirements to a more comfortable standing.

This is an important step and while huge in it's accomplishment in and of itself it is just one of many small steps that must be taken in order to make deep space travel both reasonably safe and relatively inexpensive. Patience, Padawan :)

 

[mheslep]

I'm still not seeing what you're trying to say here - what, specifically, would need to be brought back down?

The ISS and Shuttle provide a lot of habitation capability, for long to very long term. Capsules not so much. So, for example, in a future with not ISS, no Shuttle, what to do with a crew in a capsule that's disabled for some reason and can't re-enter. Or, how does one accomplish a two week service mission on some orbital instrument like Kepler, requiring multiple EVAs in large maneuver packs and requiring some kind of capture (as with the Shuttle arm)?

 

[mheslep]

...keeping an eye on developments in many areas such as VASIMR

A manned Mars mission is probably doable with proven, current technology. On the other hand, VASIMR is nowhere close to feasible yet, so it means decades more waiting. Also, going to Mars on the slow road keeps open the possibility of an un-powered return loop in the case something goes wrong outbound. Going to Mars fast in the case of a loss of thrust power near Mars guarantees a tour of beyond Mars.

 

[HyperTechno]

It cannot do some thing the old shuttle could (getting heavy/large things back to Earth), but those things are not needed anyway.

hmmm. They'll build a better 1 when they need!

 

[HyperTechno]

I haven't seen any discussion about an obvious application of this technology for a Mars mission. That being, some sort of large rocket will be needed, on Mars, to get our people off of Mars and on their way home. The ability to land a large rocket in a condition which is almost immediately re-usable seems like a prerequisite accomplishment for the Mars mission.
How much of the technology developed to land the first stage of the Falcon form sub-orbital altitude and velocity on Earth, will be applicable to landing a complete, and fully fueled, and ready to use rocket on Mars from Martian orbit?

Well I have the same question. Can Some 1 answer this please?

 

[cjl]

The ISS and Shuttle provide a lot of habitation capability, for long to very long term. Capsules not so much. So, for example, in a future with not ISS, no Shuttle, what to do with a crew in a capsule that's disabled for some reason and can't re-enter. Or, how does one accomplish a two week service mission on some orbital instrument like Kepler, requiring multiple EVAs in large maneuver packs and requiring some kind of capture (as with the Shuttle arm)?

All the speculative designs I've seen involve having some habitation area that is not designed for reentry, and the capsule itself is just used for reentry (and it would detach shortly before the reentry occurs). As for service missions, most current satellites are not designed to be serviceable, and in most cases (including Hubble, at least by some estimates), it is cheaper to just launch an entire new satellite rather than trying to service an existing one. However, if you really needed to service one, again, send up the tools needed to service the satellite (and possibly also a long-term habitation area) with the capsule, and the overall payload requirements will still be less than for a shuttle-like vehicle.

 

[mfb]

The ISS and Shuttle provide a lot of habitation capability, for long to very long term. Capsules not so much. So, for example, in a future with not ISS, no Shuttle, what to do with a crew in a capsule that's disabled for some reason and can't re-enter. Or, how does one accomplish a two week service mission on some orbital instrument like Kepler, requiring multiple EVAs in large maneuver packs and requiring some kind of capture (as with the Shuttle arm)?

The ISS is a backup option for a very narrow range of orbits only. A space shuttle that cannot re-enter would have had the same problem.
3 tons of payload can support a crew for quite some time.
No idea about robotic arms.

I haven't seen any discussion about an obvious application of this technology for a Mars mission. That being, some sort of large rocket will be needed, on Mars, to get our people off of Mars and on their way home. The ability to land a large rocket in a condition which is almost immediately re-usable seems like a prerequisite accomplishment for the Mars mission.
How much of the technology developed to land the first stage of the Falcon form sub-orbital altitude and velocity on Earth, will be applicable to landing a complete, and fully fueled, and ready to use rocket on Mars from Martian orbit?

The launch payload would be a single capsule with humans and a few rock samples, if we use a Dragon v2 this is about 5 tons. Mars surface to orbit just needs ~3.5 km/s (plus <10% for gravity drag), that is significantly below the capacity of the second stage of Falcon 9. Using this second stage without modification but with less fuel, we get another 4 tons of structural mass, the specific impulse of 340 seconds would suggest a lauch mass to dry mass ratio of ~3, so we need an estimated 27 tons on Mars, maybe a bit more. This happens to match the dry mass of the first stage (26 tons). The current second stage doesn't have landing gears, but we did land something of that mass on Earth with 3 times the surface gravity.

Cross-check: The second stage has a maximal thrust of 800 kN, sufficient to accelerate 27 tons by 32 m/s, or roughly 10 times the Martian surface gravity.

All SpaceX-related numbers from this page.

 

[Monsterboy]

http://www.nbcnews.com/tech/innovat...acex-falcon-9-rocket-ready-fire-again-n488926

Elon says the first stage is 'ready to fire again' but...

Though this particular history-making rocket appeared to be unscathed, Musk has said it's unlikely to be used for another mission and will probably be put on display instead.

"I think we'll probably keep this one on ground," Musk said after the landing. "Just because it's kind of unique, it's the first one that we've brought back. So I think we'll probably keep this one on the ground, but just confirm through tests that it could fly again."

 

[HyperTechno]

What about the cost of fuel used on landing the 1st stage back on ground? and also the cost of repairs?
aren't they expensive more or equal to the cost of building a new 1st stage?

 

[Monsterboy]

What about the cost of fuel used on landing the 1st stage back on ground? and also the cost of repairs?
aren't they expensive more or equal to the cost of building a new 1st stage?

No , that's the whole point of a reusable rocket ,the cost of fuel is very very less compared to the cost of the rocket ,this has been made clear earlier in this thread , the cost of repairs will also be very less compared to building a new rocket unless something goes wrong and the rocket crashes (in this case i don't think it can be repaired).

 

[mfb]

What about the cost of fuel used on landing the 1st stage back on ground? and also the cost of repairs?
aren't they expensive more or equal to the cost of building a new 1st stage?

See the previous posts, fuel is below 1% of the launch costs, and the additional fuel needed to get back is a small fraction of this 1%. The repair costs will need more long-term experience to get a reliable estimate, but the goal is to have it ready for flight within hours, so basically no repairs necessary.

It is really similar to an airplane - building a new one for each flight would be ridiculous even if you have to fly the existing airplane back empty.

 

[cjl]

See the previous posts, fuel is below 1% of the launch costs, and the additional fuel needed to get back is a small fraction of this 1%. The repair costs will need more long-term experience to get a reliable estimate, but the goal is to have it ready for flight within hours, so basically no repairs necessary.

It is really similar to an airplane - building a new one for each flight would be ridiculous even if you have to fly the existing airplane back empty.

Well... it's not quite that simple, unfortunately. The rocket does need to be bigger and heavier to lift the same payload, since it now needs to carry the extra fuel and equipment to allow the stage to return and land, and the launch profile used for this flight (and presumably all reusable flights) is rather different than what you would normally want (it was fairly lofted, with the first stage giving the rocket less overall delta V and downrange distance than you normally would). This trajectory required the second stage to be larger and more powerful than it would otherwise need to be to make up for the shortfall in downrange performance from the first stage. Since the second stage is not reused, any additional performance from the second stage is still rather expensive. However, despite these tradeoffs, SpaceX still believes they can save a lot of money through the boostback, and I would tend to believe them on that. I just want to point out that there are some other considerations on top of just adding the cost of the extra fuel for the boostback though.

 

[mfb]

The second stage has a fixed size, SpaceX cannot use a smaller one. Yes, returning to the launch pad reduces the maximal payload, but the payload was light enough to allow such a mission. Heavier payloads will have the first stage land on the drone ship, and even heavier ones get an expendable rocket (or move to Falcon Heavy in the future). That's something I wrote at least 5 times now in this thread. The Falcon 9 is cheaper than many smaller rockets - even without the re-use feature.

 

[cjl]

The second stage has a fixed size, SpaceX cannot use a smaller one. Yes, returning to the launch pad reduces the maximal payload, but the payload was light enough to allow such a mission. Heavier payloads will have the first stage land on the drone ship, and even heavier ones get an expendable rocket (or move to Falcon Heavy in the future). That's something I wrote at least 5 times now in this thread. The Falcon 9 is cheaper than many smaller rockets - even without the re-use feature.

The second stage has a fixed size, and that fixed size is larger than it would be if they had designed the rocket to be disposable while still carrying its' typical payload capacity. It's true that the design is fixed now, but the whole rocket design was based around the concept of reusability, so you can't just claim that everything would be the same size (and cost) if they had designed it as a disposable rocket from the start.

 

[mfb]

The baseline so far is a disposable rocket. The re-usable version is a modified first stage. A bit heavier and with a lower payload capacity. Well, "lower" - the Falcon Heavy will beat the heaviest operational system (Delta IV Heavy) by nearly a factor 2 (and cost ~1/4 per launch). Even with re-use of all three cores, it will have a higher payload capacity than all other rocket systems currently in use.

 

[cjl]

The baseline so far is a disposable rocket. The re-usable version is a modified first stage.

Yes, but the Falcon 9 was designed from the start with reusability in mind, and many of the design decisions were based around that, especially if you look at the "V1.1" and newer variants (which were a pretty heavy redesign compared to the originals). If you designed a rocket from scratch for disposability, it wouldn't necessarily end up with the same set of compromises.

Oh, and as for the FH, I'll believe the cost numbers when it's operational, though I do hope it delivers on its promises.

 

[mfb]

Well, they did sell some FH launches already, and the Falcon 9 costs are quite low as well.

 

[Monsterboy]

Since the second stage is not reused, any additional performance from the second stage is still rather expensive. However, despite these tradeoffs, SpaceX still believes they can save a lot of money through the boostback, and I would tend to believe them on that. I just want to point out that there are some other considerations on top of just adding the cost of the extra fuel for the boostback though.

I am not an expert but the problem you stated will disappear if the second stage is also made reusable right ? SpaceX's goal is to develop a fully and rapidly reusable rocket right ? So even if the payload capacity is reduced to a small extent due to the additional fuel and equipment ,the fact that the same stages are supposed to be reused several times reduces the cost over many launches IMO.

 

[mfb]

The second stage won't be reused for the current Falcon 9: Interview with Elon Musk. A following generation of launch vehicles could try that (also discussed in the video).

 

[mheslep]

Interview with Elon Musk.

Great discussion. I'm curious about some of the other issues he raises in that interview, such as the assertion that commercial e-aviation becomes viable with a one-third improvement to battery energy density, from 300 Wh/kg to 400 Wh/kg. Then there were his concerns about the power required for beam based space launch.