BepiColombo braces for third Mercury flyby

The ESA/JAXA BepiColombo mission is gearing up for its subsequent shut flyby of Mercury on 19 June, when it should go the planet’s floor at an altitude of about 236 km.

That is the third of six gravity help flybys at Mercury that ESA’s spacecraft operation workforce is guiding BepiColombo by means of. The flybys, along with greater than 15,000 hours-worth of difficult solar electrical propulsion operations, are wanted to assist the spacecraft battle towards the large gravitational pull of our sun, in order that it may ultimately lose sufficient power to be captured into Mercury’s orbit in 2025.

The closest strategy of Monday’s flyby will happen at 19:34 UTC (21:34 CEST). BepiColombo will strategy on the night time facet of the planet, that means essentially the most attention-grabbing views of Mercury’s floor might be recorded by the spacecraft’s monitoring cameras from about 13 minutes later. The primary photos are anticipated to be launched on 20 June.

Flybys and thrusters

Whereas a welcome alternative to snap photos and fine-tune science instrument operations at Mercury earlier than the primary mission begins, the first purpose for the flyby is to make use of the planet’s gravity to information BepiColombo’s path by means of the inside solar system.

The mission launched into space on an Ariane 5 from Europe’s Spaceport in Kourou in October 2018 and is making use of 9 planetary flybys: one at Earth, two at Venus, and 6 at Mercury, to assist steer into Mercury orbit.

After this flyby, the mission will enter a really difficult a part of its journey to Mercury, steadily rising using solar electrical propulsion by means of extra propulsion durations known as “thrust arcs” to repeatedly brake towards the large gravitational pull of the sun. These thrust arcs can final from just a few days as much as two months, with the longer arcs interrupted periodically for navigation and maneuver optimization.

Cosmic slingshot

Mercury is the least explored rocky planet of the solar system, with one of many important causes being that getting there’s actually troublesome. As BepiColombo will get nearer to the sun, the highly effective gravitational pull of our host star accelerates the spacecraft in the direction of it.

Gravity help flybys are a good way to alter course utilizing little or no gasoline, however they’re removed from easy.

Flight controllers are prepared to exactly information BepiColombo in order that it passes Mercury at precisely the appropriate distance, from the appropriate angle, and with the appropriate velocity. All of this was calculated years in the past, however must be as near good as attainable on the day.

“As BepiColombo begins feeling Mercury’s gravitational pull, it is going to be touring at 3.6 km/s with respect to the planet. That is simply over half the velocity it approached with throughout the earlier two Mercury flybys,” explains ESA flight dynamics skilled Frank Budnik.

“And that is precisely what the purpose of such occasions is. Our spacecraft started with far an excessive amount of power as a result of it launched from Earth and, like our planet, is orbiting the sun. To be captured by Mercury, we have to decelerate, and we’re utilizing the gravity of Earth, Venus and Mercury to just do that.”

On 19 Might, groups at mission management carried out the biggest chemical propulsion maneuver the mission has seen. The aim was to appropriate errors in BepiColombo’s orbit that had collected because of thruster outages throughout the earlier one-and-a-half month-long, gradual electrical propulsion arc. Correction maneuvers on the strategy to a flyby are a part of regular operations; with out this one BepiColombo could be 24,000 km too removed from Mercury and on the improper facet of the planet!

To be on the secure facet, and to make sure no likelihood the mission may find yourself on a collision course with Mercury, the most recent maneuver was designed in order that BepiColombo would go the rocky planet at a barely increased altitude than wanted. The additional margin was a superb wager and canceled out earlier errors that had crept in because the spacecraft traversed thousands and thousands of kilometers by means of space. One week out from the flyby BepiColombo is now predicted to go the planet’s floor at an altitude of 236 km (+/- 5 km).

In the mean time of shut strategy BepiColombo may have accelerated to five.4 km/s with respect to Mercury courtesy of the planet’s gravitational pull, however the flyby will general scale back the spacecraft’s velocity magnitude in comparison with the sun by 0.8 km/s, and alter its path by 2.6 levels.

“That is the primary time that the advanced solar electrical propulsion technique is getting used to get a spacecraft to Mercury, and it represents an enormous problem throughout the remaining a part of the cruise phase,” says Santa Martinez Sanmartin, ESA’s BepiColombo mission supervisor. “We now have already tailored our operations idea to have extra communications passes with our floor stations, enabling us to recuperate sooner from thruster interruptions and to enhance orbit willpower. And all of the whereas that is working with communications delays of greater than ten minutes as a result of time it at the moment takes gentle alerts to journey between Earth and the spacecraft.”

Flight dynamics is each a science and an artwork. Orbits, maneuvers and flybys are decided years prematurely, however spacecraft aren’t good mathematical objects. For this reason groups at all times err on the facet of warning, factoring in a number of alternatives for maneuvers to hone and proper a spacecraft’s precise path.

Tastes of science

Whereas many devices have been activated throughout the cruise phase, some may also function throughout the flyby, offering one other tantalizing glimpse of the Mercury science anticipated throughout the primary mission. Magnetic, plasma and particle monitoring devices will pattern the surroundings earlier than, throughout and after closest strategy.

This would be the first flyby for which the BepiColombo Laser Altimeter (BELA) and Mercury Orbiter Radio-science Experiment (MORE) might be switched on, albeit within the case of BELA for useful check functions solely. As soon as in Mercury orbit, BELA will measure the form of Mercury’s floor, and MORE will examine Mercury’s gravitational discipline and core.

“Accumulating knowledge throughout flybys is extraordinarily useful for the science groups to test their devices are functioning accurately forward of the primary mission,” says ESA’s BepiColombo undertaking scientist Johannes Benkhoff. “It additionally supplies a novel alternative to check with knowledge collected by NASA’s MESSENGER spacecraft throughout its 2011–2015 mission at Mercury from complementary areas across the planet not normally accessible from orbit. We’re delighted to have already got knowledge printed primarily based on our earlier flybys that generated new science outcomes, which makes us much more excited to get into orbit!”

Upon arrival at Mercury in December 2025, BepiColombo’s two science modules—ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO)—will separate from the Mercury Switch Module (MTM) and enter complementary orbits across the planet.

The primary science digicam is shielded till the spacecraft modules separate however throughout flybys snapshots are taken by BepiColombo’s monitoring cameras.

A singular selfie

Through the closest strategy, BepiColombo might be in Mercury’s shadow. The illuminated a part of the planet will solely enter the spacecraft’s discipline of view round 13 minutes later, when BepiColombo is at a distance of about 1,840 km.

Meaning there might be no illuminated photos from closest strategy itself. Probably the most visually interesting photos exhibiting the main points of Mercury’s floor might be captured between about 13 and 23 minutes after shut strategy.

The cameras present black-and-white snapshots in 1024 x 1024 pixel decision. Due to their place on the spacecraft, in addition they seize one in all MTM’s solar arrays and the MPO’s antennas within the foreground of the pictures. As BepiColombo passes Mercury, we are going to see the planet seem within the high proper of the M-CAM 3 photos and transfer in the direction of the underside left.

The primary photos might be downlinked inside a few hours after closest approach and are anticipated to be accessible for public launch from the afternoon of 20 June onwards. The closest photos are anticipated to disclose a bunch of outstanding geological options together with massive craters, volcanic and tectonic terrain.

All photos may also be launched in ESA’s Planetary Science Archive within the following days.