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45 minutes ago, sevenperforce said:

The Atlas booster made it to orbit but rapidly decayed. The Mercury capsule had two solid motor packages, one for circularization and one for deorbit. The deorbit module had three different motors in case one failed.

Have a source on that? Not to challenge but I’d always heard Mercury was stuck wherever the Atlas left it, until return time.  

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5 minutes ago, CatastrophicFailure said:

Have a source on that? Not to challenge but I’d always heard Mercury was stuck wherever the Atlas left it, until return time.  

There were 2 sets of 3 SRMs. The first separated the spacecraft from the booster, it would make sense to have that leave the booster to decay.

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8 minutes ago, CatastrophicFailure said:

Have a source on that? Not to challenge but I’d always heard Mercury was stuck wherever the Atlas left it, until return time.  

It was. Those dinky posigrade motors didn't circularize the orbit, they just accelerated Mercury clear of the Atlas. Those were merely separation motors.

Edited by Guest
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19 minutes ago, CatastrophicFailure said:

Have a source on that? Not to challenge but I’d always heard Mercury was stuck wherever the Atlas left it, until return time.  

Mercury had no translation thrusters for changing its position in space, only pitch, yaw, and roll jets. However, they did have a total of six solid motors strapped (literally with leather straps) under the heat shield, 3 posigrade and 3 retrograde. The posigrade motors separated from the booster and performed final circularization; the retrograde motors deorbited. 

LjK5e4rppIK-hpRZJjickAGVgoCgm9RHFcnnfypv

The larger nozzles are the retrograde motors; the smaller ones are the posigrade motors. 

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1 hour ago, tater said:

STR_7.jpg

STR_5.jpg

Is it really better to launch without stowing the flaps? Seems like they could minimize the aerodynamic load by keeping them close to the hull.

I guess one reason not to do that would be because stowed aero surfaces can induce torque, so it's better to keep the whole thing symmetrical. Kind of how front ailerons canards can make a plane pitch up.

Edited by Wjolcz
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2 hours ago, tater said:

STR_7.jpg

 

This looks a lot like the typical sci-fi spaceship images. Arriving at an body you always come in engine first. 
Note this could be  second pass and you  are going for an moon at the right of us. 
And no starship is not up for an manned mission to Saturn. It probably launch the parts for the ship however. 

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10 hours ago, tater said:
12 hours ago, sh1pman said:

ock1. Both drop the core stage before LEO, engines don’t count in both cases. Would SLS get more cargo to LEO if they removed upper stage completely?

There were proposed cargo variants of Shuttle (Shuttle C, Shuttle HLV) that made a cargo pod with SMRs on the back and put it where the Orbiter would go. The pod has fairings, and you can lift large cargoes on the order of 70-90t.

So for actual payloads, that's a better number. My point in general was that with a reusable vehicle, particularly a crew vehicle, the vehicle itself IS the payload. It was like @mikegarrison's point about satellite service, if that's the sort of thing you need to do, you need Shuttle (or something similarly capable). The Orbiter being a thing you need in LEO, that makes it a payload, not a container to take a payload. I suppose the other way would be a further deconstruction that calls the astronauts and their required gear to do some job the payload, and everything that keeps them alive, etc doesn't count. Food? Not payload, that's payload support, humans are the payload :) . Again, it's a tricky thing to compare, honestly.

So for comparing boosters or stage1/stage2 stacks, the total mass to LEO is a valuable tool for comparing them. If you have actual stand alone cargo, then the actual cargo capacity matters (what it can actually carry under the fairing or inside a cargo bay). Shuttle and SLS confuse things a little with the sustainer architecture since they burn the main engines virtual

Agree, starship is likely to tilt this even more its heavier and more capable than the shuttle but also one or close to two magnitudes cheaper to launch. 
You might well see they do missions to test some ion engine, while having tourists wanting a week in space. Also deploying some tons of satellites. 
The ion engine test was main objective, the tourists and satellites was the money makers. 
Kind of how many ferries  in Europe are mini cruses.

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16 minutes ago, magnemoe said:

This looks a lot like the typical sci-fi spaceship images. Arriving at an body you always come in engine first. 
Note this could be  second pass and you  are going for an moon at the right of us. 
And no starship is not up for an manned mission to Saturn. It probably launch the parts for the ship however. 

It can still be first pass. It can be going from right to left. The sun is slightly up and right.

Not that I imagine a crew vehicle at Saturn while Starship is still a thing.

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2 hours ago, sevenperforce said:

Mercury had no translation thrusters for changing its position in space, only pitch, yaw, and roll jets. However, they did have a total of six solid motors strapped (literally with leather straps) under the heat shield, 3 posigrade and 3 retrograde. The posigrade motors separated from the booster and performed final circularization; the retrograde motors deorbited. 

LjK5e4rppIK-hpRZJjickAGVgoCgm9RHFcnnfypv

The larger nozzles are the retrograde motors; the smaller ones are the posigrade motors. 

Every source I've seen indicates that the posigrade motors really were only for separation from the booster. I read that, at least when used in the suborbital flights, they only provided about 5 m/s delta-v.

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39 minutes ago, sh1pman said:

It’s burning prograde to return to Earth.

A prograde burn is the only possible explanation, as the plumes off Enceladus clearly tip us off as to which way is which.

And there is no way I'd fly to Saturn in a crew Starship...I need some much more energetic impulse than burning methalox.

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1 hour ago, mikegarrison said:

Every source I've seen indicates that the posigrade motors really were only for separation from the booster. I read that, at least when used in the suborbital flights, they only provided about 5 m/s delta-v.

I read 50 m/s but I could be wrong.

2 hours ago, tater said:

It can still be first pass. It can be going from right to left. The sun is slightly up and right.

Not that I imagine a crew vehicle at Saturn while Starship is still a thing.

Could be a mid-course correction burn during a slingshot flyby back to Earth.

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7 hours ago, magnemoe said:

This looks a lot like the typical sci-fi spaceship images. Arriving at an body you always come in engine first. 
Note this could be  second pass and you  are going for an moon at the right of us. 
And no starship is not up for an manned mission to Saturn. It probably launch the parts for the ship however. 

It could be, if Starship was carried by a interplanetary mothership as a cargo\crew shuttle.

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2 hours ago, Scotius said:

It could be, if Starship was carried by a interplanetary mothership as a cargo\crew shuttle.

Gateway Foundation wants to build O'Neill cylinders and do just that. I don't think they will though. I also think I will be very old when I see the first one.

Edited by Wjolcz
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9 hours ago, tater said:

Not that I imagine a crew vehicle at Saturn while Starship is still a thing.

Nah, the render shows the equivalent of those horse coach rides you can currently take in Central Park, between the glass-and-steel skyscrapers of Manhattan. A veteran vehicle shined up and/or recreated for tourists.

Edited by Codraroll
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6 hours ago, Scotius said:

It could be, if Starship was carried by a interplanetary mothership as a cargo\crew shuttle.

A fast transfer to Saturn can be done in 3 years, and the return can be even faster if you do the right sort of free-return. I wonder if we could fit enough stuff in 1,000 cubic meters to keep a few people happy and healthy for five or six years.

A flyby mission  is not outside the realm of near-future possibility. It would take a fleet. 2-3 crewed Starships. 8-10 people. Two or three tankers upgraded with ZBO. Two cargo Starships, one with flatpacked unpressed supplies and one with autonomous payloads for Jupiter and Saturn. There are annual launch windows from 2025 to 2031 that provide Jovian swingbys to Saturn, and then setting up a Saturnian free-return is just a matter of math.

Use one of the cargo Starships to drop five-tonne landers on Europa, Ganymede, Titan, and Enceladus.

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