SpaceX’s Return To Flight (RTF) milestone remains on track for December, as the Falcon 9 first stage – tasked with the launch of the ORBCOMM-2 mission – arrived at its Cape Canaveral launch site early on Friday. The launch of the OG-2 mission will also be the debut of the Full Thrust version of the SpaceX workhorse.



SpaceX Falcon 9 Mission:

SpaceX has been out of action since June when its Falcon 9 v1.1 failed during first stage ascent with the CRS-7/SpX-7 Dragon spacecraft.

Evaluations into the failure have resulted in changes to the upcoming Falcon 9 fleet, which – bar the Jason-3 mission – will involve the Full Thrust Falcon 9.

The return of SpaceX to action will involve the launch of the ORBCOMM-2 mission.

No launch date has been set, with a preliminary target of mid-December currently the most-likely estimate based on what is now a confirmed shipping of the first stage to SpaceX’s launch site at Cape Canaveral’s SLC-40.

The stage had been at SpaceX’s test center in McGregor, Texas – where it underwent testing, including at least one “Full Duration” static fire on the test stand. SpaceX has not confirmed the McGregor milestones, although the subsequent road trip for the stage is a positive milestone.

The stage will enjoy another engine firing via the usual Static Fire test on the SLC-40 pad, usually around a week ahead of launch.

This test involves a full propellant loading sequence, launch countdown operations, engine ignition operations and testing of the pad’s high-volume water deluge system. In effect, it provides a full dress rehearsal for the actual launch.

Providing the Static Fire proceeds as planned, engineers will take the flow into a Launch Readiness Review (LRR), which will then confirm the launch date for the OG-2 mission with eleven new satellites for the company.

SpaceX’s first Orbcomm launch consisted of a single satellite deployed as a secondary payload to the CRS-1 Dragon mission to the ISS in October 2012.

This ended in failure after a first stage engine malfunction left the rocket unable to reach the Orbcomm’s designated deployment orbit, despite unloading its Dragon payload successfully.

As a result, the satellite was left in an unusable orbit from which it quickly decayed, unable to fulfil its mission. This anomaly, overall a partial failure, remained the only blemish on the Falcon 9’s launch record ahead of the CRS-7 failure.

The Orbcomm Generation 2 (OG2) satellites are manufactured by Sierra Nevada Corporation, with Argon ST of Virginia producing their communications subsystems. Six were launched in 2014, with the remaining eleven from the initial contract flying together aboard this next Falcon 9 mission.

Orbcomm has options for up to thirty more satellites which can be produced for replenishment or to increase the size of the constellation should it be necessary.

Each spacecraft is based on Sierra Nevada’s SN-100A bus, with a mass of 172 kilograms (380 lb) and is designed for an operational lifespan of at least five years. The spacecraft are each powered by a gallium-arsenide solar panel producing 400 watts of electrical power.

Each OG2 spacecraft is three-axis stabilized with hydrazine thrusters used for attitude control.

The satellites’ communications systems offer transfer rates up to four megabits per second at VHF frequencies between 137 and 153 megahertz, with each vehicle also carrying an Automatic Identification System (AIS) receiver to pick up identification and tracking signals broadcast by ships at sea – Orbcomm intends to sell this data to coastguard services.

The second-generation constellation is expected to increase the capacity of the Orbcomm network six to twelve times over.

Over 50 Orbcomm spacecraft have been launched to date, with the first being the Orbcomm-X spacecraft which was deployed by an Ariane 4 in July 1991.

A technology demonstrator for the remainder of the constellation, no signals from the spacecraft were ever received. Two further demonstration launches occurred in 1993, followed by the first two operational satellites in April 1995.

The majority of the first-generation satellites were deployed in cluster launches which made use of Orbital Sciences’ Pegasus-XL rocket.

Three groups of eight satellites and one group of seven were launched between 1997 and 1999, with two more spacecraft flying atop a Taurus in 1998.

The original satellites were designed to operate for four years. However, it was not until 2008 that a replenishment launch took place, with a Russian Kosmos-3M carrying five Orbcomm Quick Launch satellites and the CDS-3 technology demonstrator.

Most of these satellites failed within a year of the launch due to problems with their attitude control systems, while those that were not rendered completely unusable could not be used to their full capacity, and within two years all six spacecraft were unserviceable.

Orbcomm was forced to lease two VesselSat satellites from LuxSpace to provide interim capacity; these spacecraft were launched in October 2011 and January 2012.

Providing the latest Falcon 9 mission with OG-2 is successful, SpaceX is set to pick up the pace to move through its busy order book. Launch dates for future missions remain speculative ahead of the company’s RTF goal – although a large amount of Falcon 9 hardware is ready to race into space.

For the Jason-3 mission, the second stage had already enjoyed a successful test firing at McGregor on November 5 (L2) conducted while the first stage for the OG-2 mission was progressing.

SpaceX is also preparing for the launch of the SES-9 satellite and the return of the Dragon, via the CRS-8/SpX-8 mission next year.

(Images: via SNC, Marc Eisenberg )@Marc944Marc) and L2’s SpaceX Section)

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