February 14, 2017 by Chris Gebhardt

Not even two days after historic launch complex 39A at the Kennedy Space Center was revived by SpaceX following retirement of the Space Shuttle, the historic Shuttle Landing Facility at the Florida spaceport is preparing toonce again host an end of mission landing as the Air Forces X-37B mini spaceplane returns from a near two year mission on orbit.

Kennedy Space Center shines as a multi-user spaceport:

The retirement of the Shuttle fleet left a rather large hole in the Kennedy Space Centers (KSCs) ability to launch and conduct human orbital space operations.

At the conclusion of the historic reusable spaceplane program, NASA vowed to transition KSC from a single-user, single rocket facility into a multi-user, multi rocket spaceport for the 21st century.

The first two steps in that plan were the initiation of reconstruction efforts of pad 39B to prepare it for the ability to launch NASAs Space Launch System rocket for Beyond Earth Orbit missions and the 2014 agreement for a 20-year lease of pad 39A to SpaceX for its Falcon 9 and Falcon Heavy rockets.

With the final Shuttle launch from pad 39A on 8 July 2011, the pad lay dormant as reconstructive efforts took place ahead of this past weekends return of fire and thrust from rocket engines for SpaceXs static fire of the Falcon 9 rocket that will loft the SpX-10 mission to the Space Station later this week.

After Atlantis final launch from Pad A, the vehicle returned for the final landing of the Shuttle program back at the Kennedy Space Center on 21 July 2011 after which the Shuttle Landing Facility (SLF) has not since hosted an End Of Mission (EOM) landing of an orbital mission.

Tomorrow, weather permitting, that will change, and two of the Kennedy Space Centers iconic elements will be back in operation within two days of each other.

With Boeing building and processing its CST-100 capsule inside former OPF Bay 3 as part of NASAs Commercial Crew Transportation services contract and last weeks completion of platform installation in the VAB for SLS stacking operations, the Kennedy Space Center is truly shining as a multi-user spaceport.

Specifically for the Air Force, the ability to use the SLF at Kennedy marks what is hoped to be the first of many uses of the SLF as the primary EOM landing facility for the X-37B which the Air Force hopes to launch, land, and refurbish at KSC and the Cape Canaveral Air Force Station.

In fact, after landing, the X-37B is expected to be towed to OPF-1 for post-flight servicing operations.

OTV-4 Fourth flight for X-37B comes to an end:

The fourth flight of the Air Forces experimental X-37B spacecraft assuming a landing on Monday, 14February 2017 will clock in at 636 days and 22 hours (approximate to its anticipated landing time).

If all goes according to plan, the X-37B will approach the Kennedy Space Center for a landing no early than0800EST (1300 UTC) though this time is approximate and based on unverified orbital tracking observations of the X-37B.

Depending on the specific path the X-37B follows in its entry sequence currently understood to be a descending node entry over portions of the United States and Florida large swathes of Central Florida could be graced with twin sonic booms during the morning commute as the X-37B rather insistently heralds its arrival back home.

The ability for this fourth mission to attempt a return to the runway at Kennedy follows three highly successful, completely autonomous deorbit, entry, and landing sequences of the first three X-37B flights, which all ended with precise touchdowns at the runway at Vandenberg Air Force Base, CA.

OTV-2 and OTV-3 landed without incident following a blown tire that led to minor underbelly damage of the OTV-1 vehicle (which subsequently flew the OTV-3 mission).

With an expected mission duration of just under 637days, the fourth flight of the X-37B program will not be the longest with that distinction going to the OTV-3 flight which lasted 674 days and 22 hours.

Nonetheless, the mission will resoundingly beat the OTV-2 mission duration of 468 days and 14 hours and the OTV-1 mission duration of 224 days and 9 hours.

Moreover, the prolonged duration of the current and previous X-37B missions highlight the secretive nature of the spaceplane, its missions, end its designed orbital lifetime which is currently listed as 270 days something which three of the four missions to date have shattered.

Presently, two X-37Bs are known to exist, with the first flying the OTV-1 and -3 missions and the second flying the OTV-2 and -4 (presumably) missions.

In all, each X-37B is 8.92 m (29 feet 3 inches) in length, has a 4.55 m (14 foot 11 inch) wingspan, has a height of 2.9 m (9 feet 6 inches), and has a maximum lift off weight of 4,990 kg (11,000 lbs).

The vehicles are powered by gallium arsenide solar cells with Lithium-ion batteries and contain a 2.1 x 1.2 meters (7 feet x 4 feet) payload bay.

In preparation for landing at Kennedy, teams practiced landing drills and post-landing safing operations as well as emergency drills at the SLF last week.

The X-37B landing also helps explain the until now curious delay to SpaceXs launch of the SpX-10 resupply mission for the International Space Station which had originally been scheduled for the 14th as well the opening day of the X-37Bs landing attemptsat Kennedy.

When the SpaceX mission was delayed, it was stated that range assets necessary for the return to launch site landing of the Falcon 9 core stage were not available from 14-17 February, while all other range assets necessary for launch were available during that window.

While the secretive nature of the mission precludes any exact knowledge of the ground track the X-37B will take, a descending node reentry over large portions of the United States is the likely option given the landing window for the restricted air space in and around the Kennedy Space Center.

A descending node entry would lead toan earliest possiblelanding at 0800EST at Kennedy, which shouldsee the X-37B put on quite a light show for portions of the United States as it reenters the atmosphere in the early morning darkness before crossing the night-day Terminator and heading for a post-sunrise landing in Florida.

While the landing per the restriction notices originally slated to occur on 14 February, there is now evidence that the USAF has scheduled a back-upopportunity fortomorrow, 15 February.

Nonetheless, the NOTAM and flight restriction zone through 3,000 feet around the SLF extendsfrom 0800-1600L on the 14th meaning a landing is possible at any time in that window when orbital mechanics allow.

Thus, 0800 EST was only the earliest possible landing for Tuesdays attempt.

With no proven orbital ground track for OTV-4 since its maneuver last week, there are only good approximations of its suspected landing time hence the estimate of 0748-0800L for the first possible landing opportunity Tuesday.

Moreover, Tuesday was just theopen day of several landing possibilities as the EasternRange, per SpaceXs slip from today to the 18th, was in conflict from 14-17 Februaryshowing that X-37Bs opportunities to land are over days, not hours.

Additionally, after the 0800 hour passed at Kennedy, the NOTAM that was in effect was officially extended to the 15th, with the same general 0800-1600L restriction times.

On Tuesday, the Pentagon aimed at deflecting the interest in the potential landing, citing it the program was conducting a regularly scheduled exercise. However, the NOTAMs remain in place at the time of the update.

(Images: USAF, ULA, Boeing, and NASA)

See the article here:

Air Force's X-37B prepares for landing at KSC's Shuttle Landing Facility - NASASpaceflight.com