Arianespace were in action on Thursday, with the launch of a Vega rocket from the Guiana Space Center in Kourou, French Guiana, carrying the Peru Sat-1 and SkySats 4, 5, 6, and 7. Liftoff was on schedule at 01:43:35 UTC on 16 September (21:43:35 EDT on 15 September) with the nearly all solid fueled Vega making its seventh trip to space.
Debuting in February 2012, Vega (Vettore Europeo di Generazione Avanzata – Advanced Generation European Carrier Rocket) is Arianespace’s expendable lightweight launch vehicle developed jointly by the European Space Agency (ESA) and the Italian Space Agency.
Development of Vega began in 1998 as a means for ESA to offer customers with small payloads – in the 300 to 2,500 kg range – access to an affordable launcher instead of moving to the US or Russian markets to avoid the more expensive medium and heavy lift Soyuz and Ariane 5 rockets for the Arianespace fleet.
In a departure from traditional liquid fueled rockets, Vega was designed as a nearly all solid propellant vehicle, with its first three stages all using Hydroxyl-Terminated Polybutadiene (HTPB) solid fuel.
The first stage burns for the first 110 seconds of flight, before separating, allowing the second stage to ignite for the next 77 seconds.
The third stage then carries the rocket for the next two minutes of flight before handing off to the Upper Stage (or AVUM, Attitude Vernier Upper Module), which is the only liquid fueled stage of Vega and is used for precise placement of payloads into their intended orbits.
The AVUM burns a combination of Unsymmetrical dimethylhydrazine and Dinitrogen tetroxide and is capable of burning for a total time of 667 seconds.
Ahead of this flight, Vega had completed six missions – all of which were successful – and currently has seven (including this latest flight) additional missions planned throughout 2017, with additional purchases of Vega rockets through 2018.
Despite the seven planned missions through 2017, Vega itself had not launched for the last nine months – with its last mission being the launch of the LISA Pathfinder technology demonstrator to a Halo orbit at Earth-Sun L1 on 3 December 2015.
Peru Sat-1 and SkySats 4, 5, 6, and 7:
Planning for the mission began in earnest for Arianespace on 25 March 2015 when Peru Evry and Arianespace reached a contractual agreement for the launch of the Peru Sat-1 satellite on the Vega rocket.
Peru Sat-1 is the first Earth observation satellite for the South American nation and is managed under Peru’s CONIDA (La Comisión Nacional de Investigación y Desarrollo Aeroespacial).
The satellite will allow observations with resolutions of 70-cm from its Sun Synchronous Orbit.
Elements of the seventh Vega vehicle (numbered VV007) began arriving at the launch site in French Guiana on 7 January 2016 when the third stage was offloaded from its transport boat.
Peru Sat-1 was declared “ready to ship” to the Guiana Space Centre on 6 June, just before an issue with the payload caused the planned launch to slip from July to September.
Peru Sat-1 finally arrived in French Guiana on 8 August after an air transport flight across the Atlantic Ocean from its production facility in Toulouse, France.
By the next day, Peru Sat-1 had been removed from its transport carrier and engineers were performing receiving inspections on the craft inside the cleanroom at the S3B payload preparation facility.
Following checkout operations, technicians performed a fit check with Peru Sat-1 and its launcher hardware on 11 August.
The fit check allowed engineers to verify that the payload itself could properly “matchup” with the interfaces on its payload attach fitting.
On 16 August, engineers transported the Zefiro 23 second stage to the launch pad, where they subsequently integrated it on top of the first stage.
Peru Sat-1 was then fueled for its predicted 10 year mission on 24 August.
By 30 August, Peru Sat-1 was placed inside its dispenser system, VESPA (Vega Secondary Payload Adaptor) – despite its classification as the primary payload for the mission.
The mission’s four secondary satellites – SkySats 4, 5, 6, and 7 for Terra Bella – were integrated into position atop VESPA – where primary payloads usually reside.
The two payloads were then encapsulated into Vega’s payload fairing – after which the entire payload composite was taken to the launch pad and mated to the top of the Vega rocket on 6 September.
Final integrated checkouts proceeded without issue, culminating in 14 September with the Launch Readiness Review clearing Vega and its payloads for launch.
Following a nominal count, Vega ignited its first stage solid motor at 22:43.35 local time in French Guiana (01:43.35 UTC).
Once Vega cleared its launch tower, the rocket executed a command system through its Thrust Vector Control System to place it onto the correct azimuth – a 491 km x 508 km orbit with an inclination of 97.4 degree for SkySats 4, 5, 6, and 7 release.
After the first three solid stages burnout and separated, the AVUM ignited for about 6 mins, before cutting off for a 24min coast phase.
After this, the AVUM re-ignited for 1.5 mins – after which the SkySats were released into orbit 40mins after liftoff.
Vega’s AVUM then fired again for about 1 min followed by a second ballistic coast phase of 14 mins.
After this, the AVUM will ignited its engine one more time for a 1.5 min burn, placing it in a 98.2 degree inclination orbit with a target perigee/apogee of 667 km x 684 km.
The mission’s main payload, the Peru Sat-1, was then be released into its proper orbit 1hr, 42mins, 59secs after liftoff.
The AVUM will then ignite its engine again 1hr 52 mins 03 secs after liftoff for a disposal burn lasting 15 secs.
The AVUM is expected to reenter the atmosphere 2hrs 6mins 38 secs after liftoff, ending the seventh Vega mission.
(Images: ESA and Arianespace)