Today was the scheduled liftoff day for the fifth X-37 mission (OTV-5), and the first aboard a Falcon 9. (X-37 was designed from the start to be compatible with almost any launch vehicle, including the Space Shuttle, but its first four launches were all aboard the Atlas V.) As a bonus, since SpaceX is still unable to use their original Florida launchpad, Cape Canaveral Air Station’s SLC-40, this launch used the pad they’re adapting for Falcon Heavy, Kennedy Space Center’s venerable LC-39A. So LC-39A got to launch another spaceplane after all. 😉 (LC-39A’s last spaceplane launch was STS-135, the final flight of the Space Shuttle program, just over six years ago.)
Coverage of the ascent stops with first stage separation, as normal for classified flights*, but since this was Falcon 9, we got to see coverage of the first stage continue all the way to touchdown back at the Cape. Now, SpaceX gets to scramble to safe it and stash it safely in a hangar in advance of Hurricane Irma.
*X-37 is not a classified spacecraft, but its missions are generally classified. This one does carry one unclassified payload, the Advanced Structurally Embedded Thermal Spreader, for the Air Force Research Laboratory. It will “test experimental electronics and oscillating heat pipe technologies in the long duration space environment”. Satellites already use heat pipe technology to draw waste heat away from sensitive electronic components (since obviously fans don’t work for cooling a spacecraft computer), but this new technology will be lighter and cheaper. All the other payloads, as well as their quantity and the target orbit and any planned maneuvers, remain classified. But they are probably also experimental technologies, since X-37 offers a unique opportunity to test equipment for a long duration in space and recover it for extensive engineering analysis afterwards.
Without any fanfare, the OTV-4 mission came to an end over the weekend, landing at Kennedy Space Center’s Shuttle Landing Facility following 718 days in orbit.:
As with the previous three Orbital Test Vehicle missions, the majority of its activities remain undisclosed. However, this time the Air Force did disclose two payloads: an experimental ion thruster built by Aerojet-Rocketdyne and a NASA payload called METIS (Materials Exposure and Technology Innovation in Space) that exposed over a hundred samples of materials, such as polymers, ceramics, and more.
The fifth OTV mission has not yet been announced.
The USAF did not disclose which of their two vehicles is making this flight (OTV-4), but presumably it’s the the one that did not fly on the last one, which means both of the vehicles will now have demonstrated reusability. Payloads include a USAF ion drive experiment and a NASA materials science experiment. There’s also a CubeSat riding shotgun on the Atlas V for the Planetary Society, carrying a solar sail experiment.
Update: video of today’s landing is now up!
The first X-37B spacecraft has returned from its second trip into space (third for the program, as there are two vehicles), which lasted a record-setting 675 days, the greatest duration for any reusable spacecraft. It landed at Vandenberg AFB in Florida this morning. This is expected to be its final landing in Florida; the Air Force has leased one of the old Space Shuttle bays at the Orbiter Processing Facility at Kennedy Space Center to be its new home, and future landings are expected to take place on the Shuttle Landing Facility strip. This will be a money-saving move to avoid having to ship it across the entire continent between flights. X-37B is cheaper to move than Shuttle was, but it’s still a substantial expense.
Here’s the video of today’s landing:
A quick preview of upcoming events on the spaceflight front:
The USAF has announced that the X-37B will be coming home, probably on Tuesday. This is the third X-37B mission (OTV-3), using the same vehicle as the first X-37B flight and the first to last this long — about 22 months. This blows away the endurance record for a reusable spacecraft, which was previously held by the last two X-37 missions, and before that, by the Space Shuttle’s STS-80 mission, at 17 and a half days. The big difference is that Shuttle ran on fuel cells, so endurance was limited mainly by the amount of reactant they could carry, whereas X-37B is solar powered. The Air Force isn’t saying what it’s been doing up there or why it took this long, but in theory mission duration would only be limited by propellant margin or whatever restrictions the payload has. And obviously we don’t know what the payload is.
Next up after that is Comet Siding Springs’ astonishingly close pass by Mars — close enough that there is some concern about damage to the fleet of Mars orbiters. They’ll take some precautions, like feathering themselves to present the smallest possible target to the comet’s debris stream, but there realistically isn’t much they can do. Those which can, however, will be seizing the opportunity for some amazing comet viewing. At closest approach, it will be only 82,000 miles away. For comparison, the Earth’s geosynchronous ring is 22,000 miles up, and the Moon is a quarter of a million, so if this were flying by Earth at the same distance, it would be much closer to us than the Moon, and would be a staggeringly beautiful sight in the night sky. Closest approach will be October 19.
And then on October 23, the next new moon, we’ll get the buddy to our recent lunar eclipse. Only visible to folks in northwestern North America and a teensy bit of Siberia, this partial eclipse will still be worth watching if you’re in the viewing area. Click here to decide if it’ll be visible from your area.