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Oct 23 2020

Operations Summary – Weeks of 10/12 & 10/19/20

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Progeny Mk7-B Readies for Final Flight

Although it still needs to undergo some final integration checkouts at the start of next week, the fourth Progeny Mk7-B has been fully stacked with its payload on top. It will be the first rocket to use hardware previously flown, with the lower booster being the one that was recovered from the second mission in August. The casing and nozzle were refurbished and the solid fuel recast, saving us the full cost of a new booster (although one was originally ordered for the mission, it will now be assigned to a future Ascension Mk3 mission).

The rocket will also carry an actual payload for this final flight to allow Luciole Space Systems to test one of its probe core designs that could be used for future smallsats launched on the Mk8. We will be returning the payload without a parachute to see how much of it is destroyed and to also test the impact of the RTG casing, which was modified to fit the smaller 0.625m profile. The upper stage will also not be recovered this time, so the air brakes have been removed. More mission and vehicle details can be found on the Ops Tracker.

Kerbin II Increases Science Operations

Still operating nominally on orbit the mission team spent this past week trying out a more active schedule to allow the spacecraft to collect a greater amount of science data per day. Instead of waiting for the HDD onboard to fill up and then transmitting the data back, which was previously done twice per day, the probe now transmits the data back as it is collecting it. We did not do this originally because the power demands are right at the threshold of the ~48 watts provided by the RTG and so it’s possible at times to go into an overdraw and risk tapping the emergency backup batteries. The first few weeks of operations were therefore used to get an idea of whether the risk of this overdraw was regular or could be mitigated with software managing the collection and transmission of data. Testing showed software could pull it off and this week was proof that it worked as intended.

So the new daily schedule now is to wait for the HDD to fill up just once, which takes about 12 hours. The average data collection rate is slightly higher than our average transmission rate and there is a regular 5-10min communications gap between DSN Central and Arekibo (also a shorter gap much less often between Arekibo and KSC) so it’s impossible to keep the HDD from filling up eventually. Science operations are then suspended and the disk contents are down-linked while the remainder of the day is spent on software diagnostics and health checks. We are currently not allowing it to operate like this over the weekend to give the mission team some time off but if this routine continues without problems we could eventually also allow it to run over the weekend with only minor controller oversight.

While this leaves less bandwidth available for telecommunications use, data collection for the science mission will eventually begin to taper off well before the end of the year and we will be able to free up more time for telecomm testing. If not, activating the backup antenna will provide the extra bandwidth needed.

Ascension Mk3 Development Nearing End

The flight analysis report from what was likely the final Ascension Mk2 mission has been released, detailing how the mission overcame the previous problems and also set a new standard for ascent guidance. Now that we know the Viklun upper stage is capable of inserting itself into orbit and have a better idea of the performance of the upgraded cold gas thrusters during flight, the final design of the Mk3 is already under review. Lead Engineer Simon hopes to have a blueprint to release by the end of the month.

In additional Ascension news the Mk1-B capsule continues to undergo qualification checkouts. Currently it is still being looked over by engineers and crew to make sure it was built properly and can service all the needs of its occupants. One exercise was to have the astronauts take turns just sitting in the capsule for several hours, which would be required for any orbital mission. They all agreed it was suitable for such endurance and that for several days it could be possible with 0g and wonderful views out the windows.

Alaba Finally Bids Kerbin Farewell

After 49 recorded Mun encounters and 396 orbits over nearly 3 years (11/2/17 – 10/18/20), Alaba has finally been ejected from the system back into orbit around the sun. Current predictions show it will not be returning to visit our SOI for at least the next 31 years. You can see the entire progression of its trajectory over the years with this ginormous composite figure over on flickr. Although it may seem a bit disappointing that Alaba did not have a nice even 50 encounters, make note of the “recorded” statement because the moonlet was discovered already in orbit so it had to have had 1 more encounter to be captured, making it 50 total. However we’re not 100% sure the orbit we discovered it in, while highly-elliptical, was the capture orbit and it could have had 1 or 2 more previous encounters as well. We like to think it was 50 though.

Over the years Alaba’s fate was predicted several times and although it was originally expected to crash into Mun this was quickly found to be inaccurate when the asteroid failed to follow the projected trajectory after a few encounters. In fact this has turned out to be a major wake-up call in how we are modeling long-term propagation that deals with close encounters to bodies that make a significant trajectory change. Work on this problem is still ongoing and is vital to allowing us to plan future long-term missions through systems like Jool where its many moons can be used to assist with maneuvers. Alaba’s numerous encounters also gave astronomers more chances to be wrong about future predictions. Regular monitoring caught some encounters happening when they were not expected and this led to improved propagation modeling that now better detects future SOI encounters for any body, not just Mun.

Although it is now no longer a close target for observation and study, the data that has been collected over the years has far outpaced the ability of astronomers to analyze it. We expect Alaba’s legacy to continue for quite some time still and it remains out there, possibly becoming a moonlet again in the far future.

KerBalloon Plans for Orbital Communications

After returning from a partially successful mission this week, the low-altitude crew have already gotten together with the high-altitude crew to share their experience with planning the mission around the capability of being able to communicate through Kerbin II. Heading off into surface areas far-removed from being able to contact anyone in the past has meant also bringing along a lot of support in case something goes wrong. With the ability to call for help, even if not immediately, and with faster response available from aircraft like the Dhumla that can air drop large amounts of supplies, expeditions can be trimmed down and target areas that before would have been too costly to reach. Both crews hope to embark on a joint mission in November to a remote region of the planet.

ATN Database

The latest update for the Asteroid Tracking Network database is available here, containing 5,861 asteroids and 5 updated with new observation data. Here are the 27 asteroids that were discovered this past week.

From the Desk of Drew Kerman

Out of Character Behind the Scenes stuff

Written on 10/19/20

Well, this is progress – writing this up at the beginning of the week instead of the day before or day of. This, despite spending time with Star Wars Squadrons and going on a Netflix bingefest (Away, Evil, Warrior Nun). I will comment a bit on Away since that’s relevant here. If you’ve not heard of it Hilary Swank leads the first crewed mission to attempt landing on Mars. It’s primarily a drama, and I think it does the drama well – hits you in the feels – but it also seems like the crew was designed to spark this drama. I think it would have been more interesting to see the drama develop a bit more organically from the mission itself. So yea, don’t go into it expecting any good technical aspects (they still cry tears down their faces in the same episode they drink blobs of liquid in 0g. So much more to nitpick as well).

I am finally all caught up now on desk notes, here is the link to the last one that I skipped back in August.

Kerbin II

There is indeed actually a very small overdraw when sciencing and transmitting at the same time which can kill the batteries if left unchecked but fortunately the draw is so minor that when you enable time warp it disappears. So the “software” managing the power system is non-existent I’m just time warping. I don’t exceed 1000x warp so Kerbalism doesn’t do anything funky and that’s more than enough speed to easily get through a week of operations in a day without feeling like it’s taking up a large chunk of time.

The other challenge was tracking the amount of data being delivered now that I wasn’t going to be routinely filling up and then dumping the HDD to have a set amount (the size of the HDD) to calculate based on the number of times this is done. In the game the Kerbalism UI only tells you the total amount of science credits that have been down-linked. I asked the Kerbalism dev if there was a fixed data size per science credit but the answer was no.

Digging into the persistence save file however I was able to figure out what the values assigned to the Science{} node for the various experiments meant

  • dsc = amount in MB per point
  • sci = amount of total collected so far
  • cap = total amount to collect

So for example in the case of the solar wind experiment it collects 137.5MB per science point and a max of 8 points so 1,100MB or 1.1GB in total, which matches up to what the Kerbalism science archives UI says. So you just multiply the sci parameter by dsc to get the current MB of data collected so far. Since I have save files from every time I manage something on the spacecraft (like switching the science instruments on/off) I can go back to an earlier save, subtract the difference in sci value to get the amount of data collected since that time. Nice!

Alaba

Was nice that the asteroid was not on a hyperbolic trajectory at ejection so I could still show it in the Ops Tracker. Doing so however requires that I know the full orbit ap/pe and period which I can’t normally get from KSPTOT because it has it on an escape trajectory and won’t propagate a full orbit. I fixed this by editing the config file KSPTOT uses to load planet data to place Kerbin further away from the sun, which in turn increases the radius of its SOI. This worked great and the Ops Tracker did a perfect job showing the trajectory and position of Alaba until the point it crossed out of Kerbin’s SOI.

I’m still not sure how to show hyperbolic trajectories in the GeoGebra diagrams I’m currently using but at some point I intend to take a closer look at this web app for a new way to render trajectories.