Thursday, August 23, 2018

Vega Soars into the Sky with ESA’s Aeolus Wind-Monitoring Satellite

Aeolus lifts off. Credit: ESA - S. Corvaja

Arianespace successfully sent Europe’s wind-monitoring satellite named Aeolus to orbit on Wednesday, Aug. 22. The France-based firm used the smallest launch vehicle in its catalog, Vega, to carry out the first part of Aeolus’s mission underway.

The rocket lifted off at 6:20 p.m. local time (5:20 p.m. EDT; 21:20 GMT) from the Vega Launch Complex (SLV) located in Kourou, French Guiana.

The mission had been targeted to get underway on Aug. 21, however Arianespace decided to delay the launch by 24 hours due to unfavorable wind conditions in the local area.

The launch campaign for the mission, designated VV12 in Arianespace’s numbering system, kicked off nearly two months ago, on June 28, with the arrival of the Aeolus spacecraft in French Guiana. Throughout July, the engineers were busy integrating the rocket’s stages as well as conducting checks and fueling of the spacecraft itself.

The satellite was encapsulated in the payload fairing in early August. The stack was then transferred to the launch pad and integrated on the launcher on Aug. 10. Three days later, final preparations for the flight began with the start of propellant filling operations of the Vega booster. Final inspection of the fairing was conducted on August 18 and two days later the launch readiness review was performed which cleared the mission for final countdown operations. These began some nine hours and ten minutes prior to the launch.

With the ignition of its P80 engine, Vega started its vertical ascent, being powered by the first stage for almost two minutes. This stage then separated at an altitude of about 33 miles (53 kilometers). At this point in the mission’s ascent, control over the flight was taken over by the Zefiro 23 second stage rocket motor.

The Zefiro 23 was active for only one minute and 43 seconds until its detachment at T+3:37 minutes. Afterward, about 14 seconds later, the Zefiro 9 third stage ignited its engine and began its part of the flight. It burned for some two minutes and 39 seconds, during which the protective payload fairing was detached.

The Zefiro 9 third stage separated from the launch vehicle approximately six and a half minutes into the flight. The separation marked the start of the longest (nearly 50-minute-long) part of the mission, during which the AVUM upper stage continued the trek towards the designated orbit with the Aeolus satellite still attached to it.

AVUM ignited its engine for the first time at eight minutes and three seconds into the flight. Overall, the upper stage conducted two engine burns in order to release the payload into space at an altitude of about 200 miles (323 kilometers), almost 55 minutes after liftoff.

Manufactured by Airbus Defence and Space, Aeolus is an Earth observation satellite that weighs in at about 1.36 metric tons. The satellite platform, fitted with two solar arrays, is based on the same design as ESA’s Mars Express spacecraft, with dimensions of 13.12 by 14.27 by 5.25 feet (4.0 by 4.35 by 1.6 meters).

Aeolus is described as the world’s first space mission to acquire profiles of Earth’s wind on a global scale. The satellite is therefore equipped with an advanced laser system, the Atmospheric Laser Doppler Instrument, or Aladin for short is designed to timely and accurately measure global wind-profiles from space.

“Aladin fires a powerful ultraviolet laser pulse down through the atmosphere and collects backscattered light, using a large 1.5-meter diameter telescope, which is then analyzed on-board by highly sensitive receivers to determine the Doppler shift of the signal from layers at different heights in the atmosphere,” Airbus Defence and Space wrote on its website.

ESA expects that Aeolus will give scientists global information on the speed of the wind in near-real time. This would advance our knowledge on how wind, pressure, temperature and humidity are interlinked. The mission should provide its services from a Sun-synchronous orbit (SSO) at an altitude of about 199 miles (320 kilometers), for up to three years.

“Aeolus is set to be a game changer for understanding the dynamics of our atmosphere and it will have real-world applications by being used to improve our weather forecasts,” said Josef Aschbacher, ESA’s Director of Earth Observation Programs.

The Vega rocket that was used for Wednesday’s flight is a single-body launcher with three solid-propellant stages and a liquid-propellant upper module for attitude and orbit control, and satellite release. With a height of 98 feet (30 meters) and a diameter of 9.8 feet (3 meters), the rocket is described as being capable of placing satellites with a mass of 660–3,300 pounds (300–1500 kilograms) into polar or low-Earth orbits. This series of launch vehicles is commonly used for many scientific and Earth observation missions.

The rocket’s first stage is a one-piece solid-fuel rocket engine which has been designated as the P80. This stage is 38 feet (11.7 meters) tall with a diameter of about 9.8 feet (3 meters). Zefiro 23 is Vega’s second stage and has a height of about 27.5 feet (8.39 meters) and a diameter of 6.2 feet (1.9 meters). The rocket’s third stage, Zefiro 9, is 13.5 feet (4.12 meters) in length and 6.2 feet (1.9 meters) in diameter.

Vega’s upper stage, named Attitude Vernier Upper Module (AVUM), has dimensions of 5.6 by 6.2 feet (1.7 m × 1.9 m). It consists of two modules: APM (AVUM Propulsion Module) and AAM (AVUM Avionics Module). The first module uses an RD-843 rocket engine to boost the payload into a targeted orbit, while the second contains the main components of the avionics subsystem of the vehicle.

The first flight of the Vega booster was conducted in February of 2012. The VV12 mission is the 12th flight of a Vega booster to date.

Wednesday’s lift off was the fifth mission that Arianespace has conducted so far this year (2018). The company’s next launch is currently scheduled for September 7, when an Ariane 5 rocket is scheduled to deliver two communications satellites into orbit.

No comments:

Post a Comment