Weather conditions are expected to be broadly favorable around midday Monday, as SpaceX prepares to return to flight after an Eastern Range-enforced month-long hiatus in flights from the East Coast. Current plans call for the Hawthorne, Calif.-based organization to launch its 230-foot-tall (70-meter) Upgraded Falcon 9 from Pad 39A at the Kennedy Space Center (KSC) at 12:31 p.m. EDT, delivering the CRS-12 Dragon cargo ship on a two-day chasedown of the International Space Station (ISS).
According to the 45th Weather Squadron at Patrick Air Force Base, there exists a 70-percent likelihood of acceptable weather at T-0, with a similar outlook for the backup opportunity on Tuesday. Moreover, weekend thunderstorms may pose difficulties in securing the Upgraded Falcon 9’s first stage after it makes landfall on Landing Zone (LZ)-1 at Cape Canaveral Air Force Station, a few minutes after launch.
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CRS-12 marks the first time that SpaceX has launched as many as three successful ISS-bound Dragon cargo missions in the span of a single calendar year. It previously achieved two apiece every year since 2012, with the exception of 2013, which saw just a single Dragon head uphill to the orbiting laboratory. As outlined previously by AmericaSpace, CRS-12 is laden with 6,415 pounds (2,910 kg) of equipment, experiments and supplies to support 250 research investigations, as well as the Cosmic Ray Energetics and Mass (CREAM) external payload for installation onto the Exposed Facility (EF) of Japan’s Kibo laboratory.
In keeping with tradition and procedure, SpaceX completed a satisfactory Static Fire Test of the nine Merlin 1D+ engines of the first stage last week. “Static fire test of Falcon 9 complete,” the organization tweeted Thursday. “Targeting August 14 launch from Pad 39A for Dragon’s next resupply mission to the @Space_Station.”
The weather outlook is expected to be broadly favorable for an on-time launch on Monday and for the backup opportunity on Tuesday, with a 30-percent likelihood of violation. According to the 45th Weather Squadron at Patrick Air Force Base, the risk of afternoon thunderstorms over the weekend is expected to yield an elevated chance of infringing the Cumulus Cloud Rule and Flight Through Precipitation Rule on both days. “Still, the time of launch is promising, as only very unstable days generate deep convection before planned liftoff time of 12:31,” it was noted in the L-2 weather briefing on Saturday. “Maximum upper-level winds will be from the east at 25 knots at 35,000 feet.”
For only the sixth time, tomorrow’s launch will attempt to land the first stage of the Upgraded Falcon 9 on solid ground at LZ-1 at the Cape. Although its success rate to date has drawn much attention, the riskiness of this procedure is such that it is ordinarily employed for relatively low-energy launches to low-Earth orbit, such as ISS-bound Dragons. First trialed with spectacular success in December 2015, LZ-1 has seen five boosters return to Earth and land, intact, after completing their share of propelling payloads uphill.
First-stage landings are often described by SpaceX as “experimental” and of secondary importance, when placed alongside the successful delivery of payloads into orbit. However, with the touchdown of tomorrow’s first stage scheduled about eight minutes after launch—around 12:39 p.m. EDT—there remains a possibility that the post-landing securing of the vehicle may be problematic. “After landing time Monday,” noted the 45th Weather Squadron, “storm chances will increase, potentially impacting first-stage securing.”
Assuming an on-time launch on Monday, the Upgraded Falcon 9 will deliver CRS-12 onto a two-day voyage to the space station. Dragon will be grappled by the 57.7-foot-long (17.6-meter) Canadarm2 robotic arm on Wednesday morning and robotically berthed at the Earth-facing (or “nadir”) port of the Harmony node. At the controls of the Canadian-built arm will be Expedition 52 Flight Engineer Jack Fischer of NASA, backed-up by Italian astronaut Paolo Nespoli. Current plans are for CRS-12 to remain attached to the ISS until 10 September.
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