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If physics had a mafia, I’m pretty sure the BICEP2 mess would have ended in bloodshed.

ESA - BepiColombo Mission patch. 5 December 2018 BepiColombo, the joint ESA/JAXA spacecraft on a mission to Mercury, is now firing its thrusters for the first time in flight.

BepiColombo approaching Mercury

On Sunday, BepiColombo carried out the first successful manoeuver using two of its four electric propulsion thrusters. After more than a week of testing which saw each thruster individually and meticulously put through its paces, the intrepid explorer is now one step closer to reaching the innermost planet of the Solar System. BepiColombo left Earth on 20 October 2018, and after the first few critical days in space and the initial weeks of in-orbit commissioning, its Mercury Transfer Module (MTM) is now revving up the high-tech ion thrusters. The most powerful and high-performance electric propulsion system ever flown, these electric blue thrusters had not been tested in space until now.

Twin ion thrusters firing

It is these glowing power-packs that will propel the two science orbiters – the Mercury Planetary Orbiter and Mercury Magnetospheric Orbiter – on the seven-year cruise to the least explored planet of the inner Solar System. “Electric propulsion technology is very novel and extremely delicate,” explains Elsa Montagnon, Spacecraft Operations Manager for BepiColombo. “This means BepiColombo’s four thrusters had to be thoroughly checked following the launch, by slowly turning each on, one by one, and closely monitoring their functioning and effect on the spacecraft.” Testing took place during a unique window, in which BepiColombo remained in continuous view of ground-based antennas and communications between the spacecraft and those controlling it could be constantly maintained.

BepiColombo images high-gain antenna

This was the only chance to check in detail the functioning of this fundamental part of the spacecraft, as when routine firing begins in mid-December, the position of the spacecraft will mean its antennas will not be pointing at Earth, making it less visible to operators at mission control. The first fire On 20 November at 11:33 UTC (12:33 CET), the first of BepiColombo’s thrusters entered Thrust Mode with a force of 75 mN (millinewtons). With this BepiColombo was firing in space for the very first time. Three hours later, the newly awakened thruster was really put through its paces as commands from mission control directed it to go full throttle, ramping up to 125mN – equivalent to holding an AAA battery at sea level. This may not sound like much, but this thruster was now working at the maximum thrust planned to be used during the life of the mission.

ESA Malargüe tracking station

Thrust mode was maintained for five hours before BepiColombo transitioned back to Normal Mode. The entire time, ESA’s Malargüe antenna in Argentina was in communication with the now glowing blue spacecraft – the colour of the plasma generated by the thruster as it burned through the xenon propellant. These steps were then repeated for each of the other three thrusters over the next days, having only a tiny effect on BepiColombo’s overall trajectory. The small effects that were observed allowed the Flight Dynamics team to assess the thruster performance in precise detail: analysis of the first two firings reveals that the spacecraft was performing within 2% of its expected value. Analysis of the last two firings is ongoing.

Animation visualising BepiColombo’s journey to Mercury

“To see the thrusters working for the first time in space was an exciting moment and a big relief. BepiColombo’s seven year trip to Mercury will include 22 ion thrust arcs – and we absolutely need healthy and well performing thrusters for this long trip,” explains Paolo Ferri, ESA’s Head of Operations. “Each thruster burn arc will last for extended periods of up to two months, providing the same acceleration from less fuel compared to traditional, high-energy chemical burns that last for minutes or hours.” During each long-duration burn the engines do take eight hour pauses, once a week, to allow the ground to perform navigation measurements in quiet dynamic conditions. The first routine electric propulsion thrust arc will begin in mid-December, steering BepiColombo on its interplanetary trajectory and optimising its orbit ahead of its swing-by of Earth in April 2020.

BepiColombo Earth flyby

Why Do All The Planets Orbit In The Same Plane?

“So why are all the planets in the same plane? Because they form from an asymmetric cloud of gas, which collapses in the shortest direction first; the matter goes “splat” and sticks together; it contracts inwards but winds up spinning around the center, with planets forming from imperfections in that young disk of matter; they all wind up orbiting in the same plane, separated only by a few degrees — at most — from one another.”

When we look out not only at our own solar systems, but at the solar systems we’ve found around other stars, we find they have a remarkable feature in common: their planets all appear to rotate in the same plane. They might be off by a handful of degrees, but as far as we can tell, they all align with one another. This isn’t some mere coincidence, but seems to be a consequence of how solar systems form in the first place. Just as spiral galaxies orbit in the same, single plane, so do solar systems. Remarkably, it seems to be the same process at play: large structures collapse, which they do faster in one direction, and then angular momentum takes over, forming a disk. Over time, imperfections in the disk fragment, causing clumps to form and grow over time. When all is said and done, the survivors are all left in the same, single plane.

Clearest Infrared Image of Milky Way’s Central Region Unveiled

The sea. 

Each color is a sine function. The height is constant because sin(t+0*2*pi/5 )+ sin(t+1*2*pi/5)+sin(t+2*2*pi/5)+sin(t+3*2*pi/5)+sin(t+4*2*pi/5)=0 for all t value.