sevenperforce

Definitely no savings -- this mission validates Falcon 9 Block 5 too. Not to mention docking, etc.

That makes sense. I guess there are covers.

Closeups make it appear that the SuperDracos are completely blocked by silver panels.

I do love the paint job on the old launch tower.

The final config includes a primed, operational LES.

Watching the crew access arm pull away...... I would be surprised if they did not launch it in final config.

Are the Superdracos not installed?

2:48 EST and we are still go.

Microbial life on the moons of our solar system is almost a better shot than not. We might not encounter it, but the odds are pretty good. One per galaxy or one million per galaxy; all we know is that we've only met one yet. Indeed. We make a mistake if we suppose that all our particulars are necessary, but we cannot discount the peculiarities. There may be many many other equally-rare peculiarities which could lead to intelligent life, but we don't know how many.

Horror!

You don't need an Earth-like planet or a Moon-like moon. There are a lot of things that are unique to Earth that impacted how life evolved but would not necessarily be necessary for life to evolve. I like the way Bill Nye presents it. We can look at our own history and see that we crossed several critical thresholds. We jumped from non-life to life. We jumped from single-celled to multicellular. We evolved social existence. We evolved intelligence. We looked to the stars. The trouble, Bill Nye explains, is that we don't know how hard it was to cross each of those thresholds. Perhaps it is very easy to evolve social existence but it is vanishingly unlikely to make the far earlier jump from single-celled life to multicellular life. On a million other Earthlike worlds there could be entire oceans filled with emergent-social colonial microbial life but not a single multicellular organism. Or perhaps the challenging threshold is in the future...it could be that our attempts to move beyond where we are now simply will never bear fruition because space is too big and lifetimes are too finite. We don't know. So any sort of mathematical estimate is poor because all those leaps are too uncertain.

From the press kit: "Anthropomorphic test device" THERE'S A STAAAAAAAARMAN WAITING IN THE SKYYYYYYYYYYYY

They all use wide-angle lenses in this business. How else do they fake the curvature of the Earth?

The math is tricky. In theory, if the chance of a civilization have the urge and the capacity to expand is nonzero, then that bleeding edge of the bell curve will breed new expanding civilizations like wildfire. But that breaks down if the child civilizations decide not to expand.

Shuttle by far. The above image is Soyuz. That's no space at all.

SRB thrust termination doesn't eject anything; it just blows the forward end of the motor open. For something like the Shuttle stack, the SRBs would have had two explosive panels, one ventral and one dorsal. Thus the ejecta would miss the Shuttle and neither push it toward nor away. The "abort SRB" function, usable only from about 80 seconds to 120 seconds, would blow the panels and then jettison and fire the separation motors a split second later. It would snuff, yes, but that rubberized bombstuff isn't going anywhere.

Blasphemy! CST-100 has no place to put a service module extension, though it does have those nifty RS-88s (or the hypergolic derivative) that can gimbal to thrust through the COM independently or in concert without any cosine losses. No idea what its Isp is, though: The CST-100's service module could conceivably be adapted to plumb auxiliary propellant lines through a docking port in the center of the SM to add a drop tank to be put into place on orbit. The Dragon 2, on the other hand, has no onboard engines suitable for LOI or Earth return. There's no way to easily adapt the architecture to add propellants for the Dracos on orbit, and even if there was, they probably don't have enough thrust for LOI. You of course do not want to use the SuperDracos due to cosine and underexpansion losses. However, Dragon 2 does have the externally-manifested cargo pay with coupling attachment. Launching with an international docking adapter inside that means that you can launch an auxiliary propulsion unit (based on the RS-88 architecture or virtually anything else) and attach in orbit, with zero modifications to Dragon 2. Either approach converts the vehicle from an LEO ferry to a cislunar ferry, provided that the vehicle delivering the additional prop has enough residuals to perform TLI. And you get nice comfy eyeballs-in burns in both cases. Even with the more expensive Boeing approach, you'd be delivering up to 7 crew to LOP-G for less than a quarter the cost of delivering up to 4 crew to LOP-G with Orion on SLS Block 1.

OMG it's actually really big inside. I mean, I knew, but...damn.

A commercial crew vehicle needs 2.62 km/s to inject and return. And of course you need a launch vehicle capable of pushing 2.73 km/s past LEO.

Wouldn't be able to stay there.

What would it take to get Starliner or Dragon 2 out to LOP-G?

Challenger's breakup was inevitable, but the sequence itself is worth examination. As the starboard booster's O-ring burn-through began to sap its thrust, the TVC system on the port booster gimballed out hard in an attempt to compensate. The starboard booster's thrust kept dropping, however, and eventually the stack began to yaw to starboard. Aerodynamic stresses on the wounded booster skyrocketed and the aft attachment to the external tank, already weakened by impingement from the venting burn-through, gave way. The external tank failed, but the still-thrusting port booster did the most damage, causing accelerating yaw which resulted in vehicle breakup. The starboard booster, flopping wildly, tore off the orbiter's near wing, but at that point it was far too late anyway. Thrust termination would not have saved Challenger because the stack didn't have a full gee of thrust without the boosters at T+73 and it would have tumbled. However, the SSMEs had less than a gee even at separation; at sep (T+120) they gave about 7 m/s2. So if the STS had been equipped with thrust termination on the boosters and that O-ring had lasted only a dozen seconds more, there would have been at least twenty seconds--fully a 6th of the booster burn time--during which a thrust shortfall could have triggered simultaneous booster shutdown and clean separation, with the SSMEs having just enough sustainer authority to keep the stack flying straight. It still would have been an abort, but it would have given them a chance.

Let's see...I've gotten it just under 3 tonnes to date. Lemme see how much further I can trim it.

Well not very well implied. So to be clear, this challenge is: Send a Kerbal into orbit And bring him back to the ground alive Using staging in your vehicle at some point For the lowest possible takeoff mass, including the Kerbal. Right?

No problem! A little more ELI9 rocket science, just for fun.... Rocket engineers generally prefer that the propellant exhaust flows out of the combustion chamber and through the nozzle, rather than out of the chamber and through the valves back into the tank. This would be bad, and you would not go to space today (or maybe ever). But of course this is intrinsically challenging. Suppose you have two tanks, one that is pressurized to 200 psi and another pressurized to 50 psi. If you hook them up and open a valve between them, the contents will flow from the 200 psi tank to the 50 psi tank, without exception. If you want the process to work in reverse, you will need to replace the valve with some machine (like a displacement pump) and add energy to the system. Perhaps with a little effort and elbow grease, you can force one tank up to 210 psi while dropping the other to 45 psi or so. The energy you used to make this change is now stored in that system. You can extract that energy, if you like, by placing a turbine or piston shaft at the valve. And this is how a rocket cycle works. Gas generator engines are less challenging because you take a small amount of propellant at low pressure, burn it at medium pressure, and then use its pressure drop along with a turbine to operate the pump. The pump does the work of forcing the rest of the propellant into the high-pressure chamber; it also steps up pressure from the low-pressure tanks into the medium-pressure gas generator. You can dump that gas exhaust overboard (Merlin 1D on the Falcon 9), or you can use it for roll control thrust vectoring like a vernier motor (Merlin 1A), or if you really want to be creative you can inject it down near the end of the nozzle where the nozzle's expansion has lowered the flow pressure (Merlin 1D Vacuum, F-1). Adding gas gen exhaust at the end of the nozzle allows it to mix with the rest of the exhaust gases, which lowers their speed slightly but improves overall efficiency. You can also build a "gas generator" which uses a completely separate loop for generating gas and spinning the turbine. The RD-107 multichamber engines which power the Soyuz launch vehicles are connected to a completely separate tank of high-test hydrogen peroxide; this is catalytically decomposed and the exhaust is used to spin the turbine. I don't know where the exhaust is dumped but it probably goes overboard. One type of engine cycle I did not mention yesterday is the "expander cycle". If you have a propellant with a ridiculously high heat capacity, like liquid hydrogen, you can actually skip the gas generator step altogether. Simply by pushing cryogenic fuel through channels around the nozzle and chamber, the hydrogen absorbs heat, boils, and expands. The expanding gas, now at higher pressure, can be used to turn a turbine that pumps the rest of the propellants into the chamber. The low-pressure hydrogen gas can be dumped or routed back into the tank to provide autogenous pressurization, injected into the end of the nozzle, or even injected into the main combustion chamber using turbine force. Of course this cycle is limited to a small number of propellants (liquid hydrogen in current vehicles; liquid oxygen in some theoretical designs) and it tends not to work for large engines. The larger a rocket engine becomes, the less heat-generating surface area it has proportional to the amount of propellant being pushed through it. The Vinci engine being designed for the Ariane 6 attempts to get around this problem by using a very very long, narrow, cylindrical combustion chamber, but that rapidly becomes a tradeoff in terms of combustion efficiency and engine mass. For more far more detailed info on expander cycles, I recommend this resource. But I digress. Where were we? Ah, yes; staged combustion. With a gas-generator engine, the gas generator can operate at a lower pressure than the main combustion chamber so long as it has a sufficient pressure drop across the turbine. But that's not the case with staged combustion. In a staged combustion engine, the low-pressure propellant is pushed by the turbopump into a ridiculously high-pressure preburner. The fuel-rich or oxidizer-rich exhaust from the preburner is passed through a turbine to run the turbopump, losing pressure, and it is this lower-pressure exhaust which is then routed into the main combustion chamber. This means that you never have to pump anything into the combustion chamber itself, because the flows into the combustion chamber are coming from regions with much higher pressure. The pressure drop across the turbine between the preburner and the chamber is used to drive the pump for the preburners themselves. Elon Musk said that in order to reach a pressure of 300 bar in the combustion chamber, they have to run the oxygen preburner at a whopping 700 bar or higher. The 400-bar drop from the preburner to the chamber is what is used to turn the turbine to force propellant out of the low-pressure tanks and into the preburner.