BepiColombo prepares for its first Mercury flyby tonight

View
comments

British-built spacecraft BepiColombo is just hours away from making its first flyby of Mercury, when it will snap pictures of the Solar System’s smallest planet as it passes within 124 miles of its surface.

The probe will make its closest approach at 00:34 BST on Saturday. 

It will only be a fleeting visit, however, because the spacecraft is travelling too fast to go into orbit and instead will race straight past the closest world to the sun. 

BepiColombo will be slowed just a little by Mercury’s gravity though, before future flybys over the coming years eventually lead to it taking up residence around the diminutive planet by December 2025.

The uncrewed probe will make use of nine planetary flybys in total: one at Earth, two at Venus, and six at Mercury, together with the spacecraft’s solar electric propulsion system, to help steer it into Mercury’s orbit. 

This pass is hot on the heels of its last Venus flyby in August, giving scientists a tantalising first taste of what’s to come in the main mission in four years.

BepiColombo will capture images and science data during the approach, although it won’t be using its high-resolution cameras because these are currently tucked away to protect them in deep space.

Instead, two of the probe’s three monitoring cameras will be taking photos from about five minutes after the time of close approach and up to four hours later.  

The first images will be released to the public early on Saturday (October 2), with the rest published on Monday morning. 

Scroll down for video 

BepiColombo launched in October 2018 and is made up of two science orbiters, one from the European Space Agency (ESA) and the other from Japan Aerospace Exploration Agency (JAXA) that will fly in complementary orbits around the planet. 

It includes the ESA-led Mercury Planetary Orbiter and the JAXA-led Mercury Magnetospheric Orbiter, which will study all aspects of the planet — from its core to surface processes, magnetic field and its exosphere.

The aim is to better understand the origin, processes currently at work, and evolution of the planet closest to our parent star. 

Travelling the 67 million miles to enter orbit around Mercury is no small task, requiring multiple flybys to speed up, or slow down, for orbital insertion. 

Gravitational flybys require extremely precise deep-space navigation work, ensuring that the spacecraft is on the correct approach trajectory.

One week after BepiColombo’s last flyby at Venus on August 10, a correction manoeuvre was performed to nudge the craft a little for this first flyby of Mercury.

The experts hope to pass very close to the distant world, just 124 miles from its surface.

As BepiColombo is more than 60 million miles away from Earth, with light taking 350 seconds to reach it, being on target to within just a mile is no easy feat.

‘It is because of our remarkable ground stations that we know where our spacecraft is with such precision,’ said Elsa Montagnon, operations manager from ESA. 

‘With this information, the Flight Dynamics team at ESOC know just how much we need to manoeuvre, to be in the right place for Mercury’s gravitational assist.

‘As is often the case, our mission’s path has been planned so meticulously that no further correction manoeuvres are expected for this upcoming flyby. BepiColombo is on track.’ 

The first image taken by the probe will be available from about 30 minutes after closest approach, and is expected to be available for public release at around 07:00 BST on Saturday. 

This will be a black-and-white snapshot in 1024 x 1024 pixel resolution, taken by cameras positioned on the Mercury Transfer Module.

‘Because BepiColombo is arriving on the planet’s nightside, conditions are not ideal to take images directly at the closest approach, thus the closest image will be captured from a distance of about 600 miles,’ said ESA in a statement. 

The spacecraft’s cameras are positioned in a way to capture its solar arrays and antennas, and as the probe changes its orientation during the flyby, Mercury will be seen passing behind the craft’s structural elements.

For the closest images it should be possible to identify large impact craters on the planet’s surface. 

Mercury has a heavily cratered surface much like the appearance of Earth’s Moon, plotting its 4.6 billion year history. 

Mapping the surface of Mercury and analysing its composition will help scientists understand more about its formation and evolution.

Even though BepiColombo is in ‘stacked’ cruise configuration for the flybys, it will be possible to operate some of the science instruments on both planetary orbiters, allowing a first taste of the planet’s magnetic, plasma and particle environment.

‘We’re really looking forward to seeing the first results from measurements taken so close to Mercury’s surface,’ says Johannes Benkhoff, BepiColombo project scientist. 

‘When I started working as project scientist on BepiColombo in January 2008, NASA’s Messenger mission had its first flyby at Mercury. Now it’s our turn. It’s a fantastic feeling!’

The upcoming first Mercury flyby falls on the 101st anniversary of the birth of Giuseppe ‘Bepi’ Colombo (2 October 1920–20 February 1984), an Italian scientist and engineer for whom the BepiColombo mission is named. 

Colombo is known for explaining Mercury’s peculiar characteristic of rotating about its own axis three times in every two orbits of the Sun. 

He also realised that by careful choice of a spacecraft’s flyby point as it passed a planet, the planet’s gravity could help the spacecraft make further flybys. 

His interplanetary calculations enabled NASA’s Mariner 10 spacecraft to achieve three flybys of Mercury instead of one by using a flyby of Venus to change the spacecraft’s flight path. 

The BepiColombo mission will build on the successes of its predecessors to provide the best understanding of the Solar System’s innermost planet to date.