May 26 2017

Operations Summary – Week of 5/22/17

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FZX-816(C) Aerocaptured by Kerbin

When it was discovered by the Asteroid Tracking Network back on May 17th astronomers were amazed to find FZX-816(C) was potentially going to brush by Kerbin so close as to actually enter its atmosphere. It was, in fact, originally projected to miss the ground by a mere 10 kilometers! When it entered the system on May 23rd, revised observations showed it was actually going to skim only 17km over the surface, still a significant brush through the atmosphere, which begged the obvious question – what was going to happen to it? Our knowledge of the composition of asteroids is still very limited. At best we can classify them into broad categories like Stony, Metallic, Carbonaceous, etc based on what we can derive of their makeup from their orbital characteristics & limited optical observation with ground-based telescopes. How well they hold together under heat and pressure no one really knows.

To prepare for this event, scientists traveled by airship from Ockr to the entry corridor and laid out several stations along the path with seismic sensors to measure any ground impacts and microphones to pick up on the asteroid’s hypersonic passage & possible mid-air breakup. Then, there was nothing to do but pull back to a safe distance and wait. An hour after the asteroid was due to enter the atmosphere late in the day on May 25th, the scientists moved back in to collect their data, noting along the way from station to station no obvious signs of large surface damage on the landscape. When they looked at the data they saw seismic evidence not of an impact but of the pressure wave striking the surface from the asteroid’s passage, along with audio recordings of the sonic booms as it traveled along the entry corridor… and back out into space!

Several hours of airship travel was necessary to bring the news back to Ockr from which it traveled over land comms much faster to reach Kravass, home of the Kravass Observatory perched atop the 5km+ mountain under which the caverns reside. By now it was already well into the day’s first night cycle so the team at the observatory rushed to setup the infrared scope, expecting to pick up the asteroid’s signature easily due to the excess heat it would still be shedding after its pass through the atmosphere. They did have a lot of sky to cover though, being that it’s still a very small object and no one knew its size or shape well enough to even begin to predict how a pass through the atmosphere would affect its orbit. It took two night cycles of observing before the elusive target was finally spotted, and during the following night cycle (3rd sunset to 4th sunrise today) its orbit was locked down:

The current orbit of FZX-816(C) is in blue, the original orbit is in red. The yellow patch of orbit is where the asteroid was during the time it was being hunted, which you can see was a significant deviation from where it would have been if Kerbin had no atmosphere. The asteroid has in fact been captured into orbit around Kerbin, with a period of 8 days, 21h23m04s. However it is still on a trajectory that intercepts Kerbin’s atmosphere and will remain so until it does eventually either crash into the ground or not survive one of its aerobrake passes. It is next scheduled to enter the atmosphere on June 3rd @ 19:21:01 UTC, where it will pass over Sea Ring Crater. The construction of the Arekibo Radio Observatory there will have to be halted during this event – the builders have been notified already. Again scientists will setup audio & seismic stations to record what happens. In the meantime, you can check out more details on FZX-816(C) & its current location using our Operations Tracker. The Kerbal Astronomical Society has already begun discussions for choosing a name.

Genesis Program Concludes: Fly High to Go Long (If Needed)

It’s one thing to run the numbers and say how something should happen, but always better to be able to verify calculation in actual practice, which is what the Genesis Program did when they had first Captain Jebediah and then Commander Valentina fly the new Civvie aircraft home from Kravass. They both followed the exact same route (with some minor deviation due to pilot navigational errors) but Jeb flew at 2km while Val took her flight up to 4km. Engineers have studied the data from both flights to confirm their belief that flying higher is more fuel-efficient thanks to the thinner air, which causes less drag. Of course, the thin air also means less air for the propeller to push against, meaning a slower speed, but the drop in speed is much less than the drop in drag. Flying at 2km allowed the aircraft to travel an average speed of 101m/s while producing an average 0.87kN of drag. Up at 4km the aircraft flew an average speed of 99m/s but the drag force was reduced by a much larger factor to only 0.76kN on average. This reduced fuel consumption by around 24% so although Jeb managed to complete his flight roughly 2-3 minutes faster than Val even though they both traveled 530km, he consumed more fuel than she did on her flight. Still, while the gain in fuel reduction for traveling at 4km will always exceed the gain in speed for traveling at 2km, doing so only gets the aircraft around an additional 500km of range. Unless the Civvie is really going the distance to get where it needs to go, flying at lower altitudes is more feasible mainly for the comfort of the pilot, as the cabin is not pressurized and only has minimal heating – it can get as cold as 18°F up at 4km during the early hours of the day.

Progeny Mk4 #2 Looking Good for Launch May 31st

Although we said in a previous Ops Summary that we expected to launch by the end of this month, we realized today we hadn’t yet announced an official launch date and time. It has now been set to May 31st @ 17:33 UTC. After a successful static fire earlier this week the engine was refurbished and the rocket was topped off today to undergo final integration on Monday, followed by readiness checkouts and rollout on Tuesday prior to launch on Wednesday. We will be returning to the ascent profile of coasting between booster stagings, and starting with a change in pitch of 1.5° to signify the end of a coast period, with the final stage also not being allowed to drop below 100m/s of vertical speed before a staging event is triggered. Now that we know the rocket will fail under high dynamic pressure launching at full continuous thrust, we need to see how it will handle the upper atmosphere at full continuous thrust, meaning the third stage LF/O engine will ignite at 100% throttle and stay wide open the entire time. We do expect friction to become an issue as the rocket increases in speed but we don’t know how bad it will get.

KB/Genesis Mission Failure Worsens Part Shortage, Suspends Joint Missions

The fourth joint mission between KerBalloon and Genesis programs ended in failure this past week when the balloon envelope did not deploy properly after it was detached from the Civvie. Upon striking the ground, the canister of compressed gas meant to fill the balloon ruptured and blew the entire thing to bits. KerBalloon crews out to track the balloon who recovered the remains have turned them over to the Genesis program to see if they can determine what went wrong. This was Val’s first mission dropping a fully-equipped KerBalloon although she was the first to test the concept earlier this year. Both programs have already cleared her of any fault – she literally only has to press a button and reported no strike of the balloon on the aircraft, confirmed with a visual inspection after she landed back at KSC.

Until the nature of the failure is determined, KerBalloon has suspended cooperation with Genesis and will instead return to launching the balloons from the ground. They also do not feel they have seen a reasonable profit increase when teaming up with Genesis. This doesn’t limit their effective range that much, since using the aircraft to deploy the balloon rather than carrying it aboard a UTV to the deployment site only allows them to carry extra fuel to extend their range by about 200-300km. Although they anticipated contracts that would send them further from KSC, so far that has not happened.

The loss of the KerBalloon unit also included the loss of a barometer instrument and avionics unit, the latter of which is what is also known as a Master Control Unit, an integral part of any probe used in both KerBalloon and Progeny missions. It is an expensive part and so not many have been ordered since KSA began operations. This was the second to last MCU available and with the final MCU already integrated into the second Progeny Mk4 the KerBalloon program is unable to launch any more balloons until additional units arrive on Jun 2nd. These will be followed by additional units later in the month so that we eventually end up with 10 units to trade between the programs. We are also awaiting the arrival of replacements for several scientific instruments. Head of Finances Mortimer is working on a new budget that will allow for increased expenditure in part requisitioning.

ATN Database Update

The weekly update for the Asteroid Tracking Network database was posted here. It contains now a total count of 588 asteroids.

Celestial Snapshot of the Week

We are nearing opposition with Sarnus next month which means its size has increased as we continue to move closer to it again and it has become a nice target for a good pair of binoculars or a small telescope, especially during events like the one shown below, which is Mun occulting the planet. You can also see Slate, Tekto and Eeloo.

From the Desk of Drew Kerman

Out of Character Behind the Scenes stuff

Written on 5/16/17

Better week, 6 real days for 7 KSA days. Less hassle and stress all around although I did sink several hours into some dumb issues. Still hoping I can at some point recoup my 3-week lead time, I’m still not happy with how little attention I can pay to over-arching story when I’m taking things so day-by-day.

Asteroid capture – not faked

I let the asteroid event play out in the game, watching it pass through the atmosphere and enter into orbit around Kerbin. I was really expecting it to heat up and explode, so I spent some time trying to figure out how to dynamically adjust the Blast Awesomeness setting using the Blast Awesomeness Modifier but the asteroid has no pre-defined resources I can use and Module Manager doesn’t know its mass at load because it’s dynamic so I can’t apply a patch for it. So I just settled at a BAM of 5 – but of course it didn’t matter cause the asteroid didn’t explode! Note that asteroids approaching Kerbin on a direct impact trajectory always explode, anything that reaches the ground is me saying it did.

This event did lead me to finding an issue I spent several hours testing, which I think may be some kind of stock bug exacerbated by mods – I have no idea to be honest and no one else seems to really be interested in it. In the end I managed to get the asteroid through periapsis at the proper altitude to end up with the final aerocapture.

Terrain scatter continuity

I take continuity very seriously, so when I had to take this photo of Kravass airport, I needed to check it against this previous photo to see if there were any obvious inconsistencies, which there were. The biggest were two evergreen trees right behind the tarmac that were not there in the overflight image. So I had to remove them and then copy/paste some of the scatter objects in the background to fill in the emptiness they left. Another problem with terrain scatter objects is that they don’t play nicely with Scatterer’s atmospheric effects – if you look at this photo you can see most of the trees in the foreground that rise high enough are treated as though they are off in the distance. I’ve had to deal with this in a number of previous photos and the solution is to just disable the depth buffer in Scatterer’s in-game menu and take another screenshot to merge the two together & remove the Scatterer effect from certain terrain scatter objects.

Seven-hour aircraft flight

The second flight from KGA to KSC I had to stop twice to go coach, leaving the game running and hoping that it wouldn’t crash. If it did I was just going to call a mis-flight and write in a bad storm that kept Val grounded for that day so I could continue to move on. Thankfully though the game did  not crash nor did my computer crash and I was able to finish the flight. It was also entirely my fault that I stayed in bed until like 1pm 😛

Landing gear – fuck it

Spent a few hours I don’t have really trying to figure out if I can salvage the landing gear for the Civvie (and Deuce probably), I made a post for help on the FAR aircraft forums. In the end I decided it’s too much time that’s needed to really tweak the wheels to where I need them and even then I still might not succeed – so fuck it. I will continue to drop the Civvie from 600m, recover and fly low over the runway before starting the loggers, and landing will just be whatever the hell it is, I mean I came down soft as a feather recently and all this shit happened anyways. On the plus side I’ve now started flying the Civvie using the actual fixed landing gear shown in all the photos and I’m happy to find that there’s really no difference at all, which is exactly what I was aiming for when I designed the alternate setup using the retractable gear.

Flight time is also now measured from the moment I enable logging to the moment the aircraft settles on the ground during landing.

Kerbals can’t lie on their backs

For this photo of Bill wrenching on a UTV I wanted to have him lying on his back, so I loaded up the Whack-A-Kerbal (has a much more boring name now, I think it’s called Object Tosser. Lame) and proceeded to knock him over every which way, but this was the best I could do. Apparently they can’t lay on their backs. How disappointing. So instead I had him lay on his stomach, because apparently that’s doable, and then I just flipped the image around. Could I have just taken an image of him standing up from the side? Sure but I was looking for better leg positioning. It should be noted that there is Kerbal Animation Suite but it’s been acting finicky lately and you can’t actually adjust a kerbal’s entire orientation – s/he will always be standing and even if you animate both legs off the ground they will just float there.

Reddit reception

Been posting a bit more of my edited hangar shots to reddit and they have been appreciated (shot 1 | Shot 2) – and oooh hey reddit is showing you the number of views your post has gotten now. That’s nice. I was also a bit disappointed the latest ops summary only got 15 upvotes and no comments but it was 100% upvoted so I’ll take that!