I’m Anthony Colangelo.

Marco Langbroek, SatTrackCam Leiden, on the curious proximity of USA 276 to ISS on the days surrounding the berthing of SpaceX CRS-11.

There’s quite a bit of shuffling going on in Russia.

This info from Koenigsmann means one of two things: they can complete the work while continuing to fly missions from 39A, or they plan to push the work to the end of the year to give themselves some time with two east coast pads operational.

Thanks to my patrons for the month of May. If you’re getting some value out of what I do here and want to send a little value back to help support Main Engine Cut Off, head over to Patreon and donate as little as $1 a month—every little bit helps.

After months of learning and experimenting with circuitry, software, 3D design, and printing, I’ve completed the final layout and design of my Kerbal Space Program controller.

Some comments from Maj. Gen. Roger Teague on Air Force funding as it pertains to the Vulcan engine downselect.

Overall, I’m quite disappointed at the missed opportunity XS-1 presented to widen the industry. It’ll take a lot to convince me that a Boeing project of this sort will ever be affordable. Boeing doesn’t have the best reputation for cost-efficiency when it comes to launch vehicles—Delta IV and SLS being the two most recent examples—and their last small launch DARPA project didn’t end well.

A four-year difference in arrival is a huge deal, for both the scientific timeline as well as the management of the program. This change cuts five years of fixed costs out of the budget. Hopefully that money can go to other parts of the mission to increase its capability or duration.

I love seeing the breadth of approaches being taken by small launch companies. Just about every entrant has a unique component to their architecture: Rocket Lab with their electric turbopumps, Virgin Orbit with air launch, Vector with mobile pad systems, to name a few.

They’ve stopped giving dates, but here are some dates.

Things people usually shout “Pork!” about are usually defensible in some way. The prime contractors for SLS are the same old insiders, the work is centralized in the same old districts, but the vehicle itself is still politically defensible as a unique capability the market does not (yet) provide. But this situation is a pretty blatant, indefensible example of the North Alabama Space Agency.

Yesterday was a great day for SpaceX, with the beautiful and seemingly-flawless launch of Inmarsat–5 Flight 4.

Curious that the ultra-secretive Blue Origin said anything about this at all. Getting out in front of it is better than letting news of a test stand failure leak out. I doubt we’ll get any other details on it, but there are a lot of questions here.

Someone over on the Rocket Lab subreddit caught a recently-posted Notice to Mariners.

Masten has successfully fired their newest and largest rocket engine six times. In the lander department, they recently lost Xaero-B during a flight, but have something in the works at Marshall Space Flight Center—interesting choice of location—which sounds quite intriguing:.

Interesting to think that if SpaceX’s constellation ambitions even approach their projections, they’d be exempt from this regulation within a decade.

That makes it the 2017 version of the annual sales I talked about last month.

After SES-10, there was a chorus of doubters saying, “Yeah, but it took a year to refurbish!” This flight should put that to bed, but then again, they’ll probably say, “Yeah, but 6 months is nowhere close to 24 hours!”