Astrobotic PM-1 mission, CLPS mission with NASA and commercial payloads Options

[Phil Stooke]

I am starting a new thread for this mission which should fly this year.

Phil

[Greenish]

Been thinking about ways to visualize the evolving fuel situation, and whether it was converging towards anything or otherwise showing trends. I thought of two ways.

• First version plots the projected zero-fuel time vs the update time, alongside a reference "out of time" line (where y=x). Some linear trendlines indicate that initially they weren't improving faster than the leak. But eventually have caught up and overall each improvement was been greater than the proportional loss during the time between updates (dy/dx > 1). But that should probably be interpreted in light of a presumably ~exponential decay...
• Second illustration tries to show that a little more directly. At each update timestamp I draw a line* to zero after the stated number of hours. Initial "fuel" value at time of anomaly report (update #1) arbitrarily set to 100, projecting backwards using slope from following update (#6, which was the first one with a time estimate). *N.B: may make more sense to think of y-axis like log(remaining fuel)? Not sure if that distinction makes a difference anymore...

And of course, between the time I started plotting and when I post this, now they're projecting to hit the Earth. Ah well.

[HSchirmer]

eventually have caught up and overall each improvement was been greater than the proportional loss during the time between updates

Well, I'd suspect that a stuck valve works both ways. Which suggests that there is now a helium & NO/NO4 froth filling the oxidizer and pressurant tanks. Which might not be so bad, having some liquid in the pressure tank might have helped to close the wonky valve.

The analogy I think of is just cracking open a warm 2 litre bottle of soda- you get an initial blast of carbonated water, but that quickly subsides and what mostly escapes the opening (here the cracked tank) is the gas, not so much the liquid.

Perhaps the trick here would be figuring out a way for 'ullage thrust' to push the "flat soda" oxidizer (and fuel) into the engine for a burn attempt?