SpaceX Falcon 9 Block 5 - SXM-8 - Launching June 6, 2020
Screenshot from SpaceX Webcast of the launch of SXM-8
Mission Rundown: SpaceX Falcon 9 Block 5 - SXM-8
Written: August 3, 2021
This time the Music is ON Radio SXM-8
SpaceX launched its 18th mission of 2021 with the Sirius XM-8 - SXM-8 - high-power broadcasting satellite. A Falcon 9 rocket lofted the SXM-8 satellite to a sub-synchronous geostationary transfer orbit (GTO) after launching from SLC-40.
The Falcon 9 will lift off on Sunday, June 6 at 00:26 EDT - 04:26 UTC from Space Launch Complex 40, at the Cape Canaveral Space Force Station, in Florida.
SXM-8 is owned and operated by SiriusXM as a part of their high-power broadcasting satellite constellation. The company ordered SXM-8 alongside its twin, SXM-7, in July 2016 to be built by Space System/Loral (SSL), now Maxar Technologies. The two SXM satellites are based on the Maxar 1300 satellite bus.
SXM-7 was launched on Falcon 9 booster B1051-7 in December 2020 and successfully reached geostationary orbit (GEO) and began in-orbit testing; however, six weeks after its launch, an anomaly occurred with its primary payload during its standard checkouts.
While the satellite bus was understood to still be operating normally, losing the payload made the satellite useless. Soon after, SXM-7 was likely placed into a graveyard orbit while the anomaly caused a delay with SXM-8’s launch from March to June 2021 due to the investigations and changes needed.
Amos-17 being encapsulated in fairings - Note the steel plate used for atmospheric penetration during ascent - It gets red glowing hot just like the titanium “Bear Claw” grid fins - Credit SpaceX
Soon after delivery at the center, SXM-8 was taken to the payload integration facility and loaded with propellant before technicians integrated it onto the Falcon 9’s payload adaptor. Soon after, the satellite was encapsulated by the Falcon 9’s 5.2 meter (17 feet) diameter payload fairing. Both of the payload fairings are brand new.
The booster supporting this mission was B1061-3, the -3 indicating the booster’s third flight. B1061-3 first flew on the Crew-1 mission which launched four astronauts to the International Space Station in November 2020. After 158 days, the booster was used again to launch the Crew-2 astronauts to the ISS in April 2021.
Now 44 days after its second flight, the booster launched again, this time to send SXM-8 on its way to a sub-synchronous transfer orbit, meaning the apogee of the orbit will be below the GEO belt location at 35,786 kilometers above Earth sea level. This is common for heavier spacecraft as it allows for cheaper, less-capable (from a payload mass to orbit standpoint) rocket’s to launch them.
Before the satellite was attached to the Falcon 9, a final static fire test needed to be completed. The fully stacked Falcon 9, without the payload, was rolled out to SLC-40 on June 2, raised vertical and tested for seven seconds at 02:32 EDT on June 3.
The booster B1061-3 launched from SLC-40 and landed on ‘Just Read The Instruction’ (JRTI) 642 km downrange due east.
SpaceX recovery fleet just finished with one retrieval, then all hands on to SXM-8 - Need sleep zzZ
The Payload
SXM-8 is a high power broadcasting satellite. The Sirius XM satellite constellation currently consists of 5 satellites in geostationary orbit. SXM-8 is one of two upcoming satellites, the other being SXM-7 which is launching in december 2020, aiming to replace the XM-3 and XM-4 satellites.
SXM-8 was built by Maxar Technologies and is based on their SSL-1300 satellite bus; a satellite bus is simply a set of core components that all satellites need (such as avionics, power, communication…) that customers can add to suit their needs.
The satellite contains two large solar arrays and batteries for on-orbit storage. SXM-8 will operate in the S-band spectrum, between 2.32 GHz and 2.345 GHz. Each satellite has an operational lifetime of 15 years, after which the satellite is moved into a graveyard orbit.
The Sirius XM satellite constellation was formed in 2008 when Sirius and XM merged into Sirius XM. The constellation provides satellite radio and online radio services to a significant portion of the world.
Sirius XM’s latest satellite SXM-7 built by Maxar, launched by SpaceX, suffered “failures” during in-orbit payload testing, the company noted in a securities filing, although it did not disclose the cause of the malfunction.
Maxar didn’t repair a design flaw on SXM-7 properly, before handing the satellite over to Sirius XM, who then asked SpaceX to launch SXM-7, which they did flawlessly. During insertion toward geostationary orbit SXM-7 underwent a series of tests, where a fatal flaw was found, and now it’s an insurance battle and blame game.
However, failures like this underscore something that is not entirely obvious to those unfamiliar with modern GSO satellites: these birds fold up nice and compact for launch but they unfold like a butterfly emerging from a chrysalis once in space.
There are truly enormous PV arrays and a complicated array of high-gain TTC antennas; uplink receiver antennas; and re-transmission antennas and RF waveguides, all the internal connections between the above; as well as internal thermal control systems to keep the electronics operable, which typically include radiators.
There's a lot going on during orbit-raising and then on-station checkouts. It's entirely conceivable that something deployable on the bird got stuck and didn't deploy properly, or that some system failed during checkouts because of a pre-existing flaw that the manufacturer thought (and hoped!) it had addressed prior to launch. It's doubtful anyone not on the Boards of Directors or executive committees of the companies involved, and their insurers, will know the details any time soon.
Even something small like a burnt out bearing on a gyroscope can bring a satellite into a heap of trouble. The Hubble Telescope had this problem repaired several times.
Just a grainy view of SLC-40 with SXM-8 from a Maxar satellite - Some sideway snapshot
LOX sphere and tanks close to the left. 4 RP-1 tanks and small Helium tanks close to the right. TEL, the Falcon 9 and SXM-8 dead center. 4 square spaced lightning towers around the launch site. Nitrogen liquid gas tanks for subcooling LOX by the first of the two left lightning towers. Storage tool shed close by just behind the launch site and integration processing hangar with spare boosters to the far left.
Oh, and the black blast trench below the launch site. Water deluge Tower out of frame.
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