sevenperforce

IIRC, concerns of an equatorial firestorm are greatly exaggerated. The cable would be very very lightweight and so it would either float down gently or it would burn up too high to cause problems.

Yeah, they want the first rover to be able to actually do some science on its own and select some more interesting samples. The second rover will be purpose-built to retrieve the samples and deposit them in the MAV.

Ditching the aerospike sucks.

And that is a beautiful thing. Actually, they can do this without modifications. The tanker and the outgoing vessel are both fully-fueled in orbit, and then they both burn almost to escape velocity, separately. Now in parallel trajectory, they mate and the tanker transfers its residuals to the outgoing vessel before decoupling. The tanker returns with high-energy entry from an eccentric orbit; the outgoing vessel completes the burn.

Ridiculously so.

Fantastic interview.

Whoops, I missed the "augmented" bit. Just saw "don't seem to use a chemical ignition system".

The BE-3 uses a consumable solid-fueled igniter.

Spark ignition in rocket engines is much trickier than in jets or ICEs; your propellant must be vaporized (not just aerosolized) and you usually have to ignite a small amount and then use that as a torch to light the main body of propellant at exactly the right time without any destructive interference or wave collisions.

Right, that's what's planned for Raptor as well, but the test Raptors use TEA/TEB: You can't use spark ignition for kerolox engines but it works great for hydrolox engines and should work well enough for methalox...or, at least, full-flow staged-combustion methalox. I don't know if it will work for ORSC.

Peak exhaust impingement on the first stage at MVac ignition is the same whether the booster is flipping or not. By the time the booster is sideways during a boostback flip, the MVac is already far enough away that impingement is essentially nil. Plus, boostback happens for many ASDS landings as well.

Aye on the latter point, but that might limit payload volume because of the curvature around the nose. Then again, BFS is not exactly volume-limited.

I guess...well, what ELSE would they be using for ignition?

Which is a great segue back to BO. Can anyone confirm that the BE-4's ignition system is TEA-TEB just like the Merlin's? I seem to recall seeing a green flash at the start of all the BE-4 fire tests. The NG first stage will likely have a much poorer mass ratio than a Falcon 9, so perhaps 1/7 of rated thrust is enough for a hover. Raptor will use spark ignition eventually.

I did my history minor senior work on the space race. A really good overall theme for comparing the USSR and the USA during the space race is to emphasize that Russia was seeking achievement milestones while the US was seeking progress milestones. The USSR got the first satellite and the first cosmonaut into orbit because they focused on short-term goals that would undergird their claims of superiority and bolster their political ends. They used a managed economy to push through whatever needed to be done; it's perhaps the most brilliant nonmilitary example of the success of a managed economy. Of course, that led to some problems. Voskhod didn't even have a bloody launch escape system. The USA, in contrast, made arguably better use of its distributed economy so lots of companies were working on the same problems in parallel. JFK named a goal and then when he died, they went all-in on achieving it. So while the USSR was hitting flashy milestones, the Americans were building a space program and solving the technical problems they would need in order to get to the moon and back in one piece. The F-1 engine was in development before the first Saturn 1 was even conceived. Also, the utility of picking up Von Braun and the other N@zi scientists cannot be understated: Ditto to everything @p1t1o said. Also, if you're doing a powerpoint slide, you should have ten words or fewer on each slide. Seriously. I aim for 5. Do NOT read a wall of text off your slide. Ever.

Can't imagine it would be. Those octawebs get torched AF on the heavyweight GTO missions.

Al grid fins used to get melty during ultra-high-velocity heavy-payload GTO missions with no boostback burn, where ASDS was maximally downrange. RTLS wouldn't have been possible under those circumstances.

Osprey has the dry mass budget to do that. A Falcon 9 does not.

That....would be unnecessarily complicated. Also impossible.

That's ULA and Vulcan. Doubt it. Flipping with cold gas thrusters in zero gees seems tame to me.

Best guess is that for any given mission, an ASDS landing means greater propellant reserves, meaning a longer entry burn and a longer landing burn. Longer entry burn means lower peak heating; longer landing burn means lower peak gees. I doubt there is anything inherent in the ASDS landing itself which reduces stresses. It's not like OCISLY appreciably cushions the touchdown or anything. That's just it, though... the advantage is the increased stability, allowing them to recover in rougher seas, and that help reduce weather-induced delays. I think the idea is that if you have big swells due to a high sea state, then steaming downwind allows the platform to move with the waves, preventing pitch and roll that would off-level the platform. The ASDS has propulsors which can damp pitch and roll, but it still must move up and down as waves pass under it, which is not something that plays well with a hoverslam landing. I can certainly see a situation where a moderately high sea state (e.g., following a storm) means that the ASDS has vertical displacement variance on the order of a couple of meters, too much for Falcon 9 to compensate for, but a fully-powered platform can simply match the local wave speed and drop vertical displacement to under a meter, enough for NG to touch down smoothly.

One option would be to eschew the solid-state approach. If you're using a "fixed" (positionally; obviously it's orbiting) tether, then you run electrical current through it to achieve your "charged particle moving perpendicular to a magnetic field" state. What if, instead, you constructed a capacitor comprising two separate, helical ribbons which counter-rotate? I'd have to take a close look at the geometry, but it's a way to potentially pack a large "cable" into a fairly small volume and avoid the need for a large electrical current flow altogether. It would be essentially an electromagnetic propeller/propulsor. Perhaps a cyclorotor arrangement could be possible. If the capacitor approach was too challenging (or if the geometry didn't close) then you could still use a counter-rotating propulsor that used an AC current to move electrical charge back and forth within the rotating frame. Again, the geometry is challenging (a bit like trying to make an overbalanced wheel), but there is a working fluid here so it should be possible.

Falcon Heavy will never perform three-core RTLS. Glenn could RTLS if it wanted to; its upper stage blows F9's away. Schedule slip due to recovery issues is an entirely valid criticism. What remains to be seen is whether there's any actual difference in recovery success (and seafaring ability) between an ASDS and whatever BO is building. If BO's ocean landing platform can self-ferry, well, that's impressive.

A high-bypass turbofan is simpler than a turboprop because it is (typically) ungeared; the bypass fan runs at the same RPM as the turbine. It is ducted, so it can operate safely at higher speeds and produce less noise. Finally, the bypass airstream mixes with the hot exhaust, allowing the hot exhaust to expand a little bit more and squeeze out a touch more efficiency, while yet again reducing noise.

I got 6:29 from liftoff to docking. Unfortunately, when the camera view changes, it scrubs MET so you can only go by the screenshot immediately preceding.