A new map of the magnetosphere of Mercury

Map of Mercury's magnetosphere
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Using data obtained during the June 2023 fly-by by the European-Japanese probe BepiColombo, scientists have now published a new detailed map of the magnetic field that surrounds Mercury.

That map is to the right. From the caption:

A textured sphere representing Mercury is shown with magnetic field lines compressed on the sunward side and streaming out into a tail on the nightside. The BepiColombo spacecraft’s trajectory is drawn passing through the magnetosphere from dawn to dusk, close to the planet’s surface. Various features in the magnetosphere are depicted and labelled with text. Following the order in which they were detected by the spacecraft, this includes the bow shock, magnetopause, low-latitude boundary layer, cold ion cloud, plasma sheet horn and ring current.

You can read the peer-reviewed paper here [pdf]. Note that this research does not include data obtained during BepiColumbo’s fourth fly-by of Mercury in September. Furthermore, the spacecraft will do two more fly-bys before arriving in orbit in 2026, where it will then separate into two separate orbiters in complementary orbits. Thus, this magnetic map of Mercury is merely a rough draft, and will be significantly refined by the end of the mission.

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ESA awards Polish rocket startup €2.4 million contract

The European Space Agency (ESA) has awarded a Polish rocket startup, dubbed SpaceForest, €2.4 million to upgrade its suborbital Perun rocket that the company has test launched twice in last year.

Perun runs on modified paraffin, commonly used as candle wax, and so its propellant is non-toxic. The rocket can be launched on a mobile launch pad, allowing for easy deployment at launch facilities around Europe. Last year, SpaceForest launched two full-scale models of its Perun rocket that flew to 22 km and 13 km altitude from the coastal town of Ustka, Poland, on the Baltic Sea.

This company is now the second Polish rocket startup to have successfully tested its rocket. The Łukasiewicz Institute of Aviation has completed suborbital test flights of its ILR-33 Amber 2K rocket, and has a deal to fly its next test from Norway’s commercial Andoya spaceport.

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Investigation into upper stage failure during Ariane-6’s first launch completed

The Ariane-6 rocket investigation team, including people from the European Space Agency (ESA), CNES (France’s space agency), ArianeGroup (which built and owns the rocket), and Arianespace (which presently manages the rocket), has identified the issue that caused the rocket’s upper stage failure during the rocket’s first launch in July.

In a 16 September update, the Task Force announced that the investigation had identified a single temperature measurement that “exceeded a predefined limit” as the root cause of the anomaly. The tripped limit caused the software to trigger a shutdown of the APU which ensured the rocket’s Vinci upper stage engine could not be restarted for the final burn.

In order to remedy this issue and ensure a similar shutdown does not occur in the future, the ignition preparation sequence, specifically the APU chill-down sequence, has been changed. The updated flight software is already being tested as teams prepare for the rocket’s first commercial flight which is set to take place before the end of the year.

Because of that incorrect temperature, the upper stage did not do its final burn, thereby stranding the stage and two demonstration return capsules in the wrong orbit. This prevented the test return of both capsules, as well as the test planned de-orbit of the stage over the ocean.

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ESA releases images taken by BepiColombo during Mercury fly-by

Mercury as seen by BepiColombo September 4, 2024
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The European Space Agency (ESA) yesterday released images taken by the BepiColombo probe as it completed its fourth fly-by of Mercury on its long journey to enter orbit around that planet.

The picture to the right, cropped, reduced, and sharpened to post here, was taken four minutes after the closest approach of about 103 miles.

Four minutes after closest approach, a large ‘peak ring basin’ came into BepiColombo’s view. These mysterious craters – created by powerful asteroid or comet impacts and measuring about 130–330 km across – are called peak rings basins after the inner ring of peaks on an otherwise flattish floor.

This large crater is Vivaldi, after the famous Italian composer Antonio Vivaldi (1678–1741). It measures 210 km across, and because BepiColombo saw it so close to the sunrise line, its landscape is beautifully emphasised by shadow. There is a visible gap in the ring of peaks, where more recent lava flows have entered and flooded the crater.

BepiColombo still has two more fly-bys of Mercury to do before entering orbit in November 2026. At that time the spacecraft’s two orbiters, one from Europe and the other from Japan, will separate and take up complementary orbits.

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Arianespace successfully completes the last launch of Avio’s Vega rocket

Tonight the last launch of the Vega rocket, built by the Italian company Avio and managed by Arianespace, successfully lifted off from French Guiana, placing a European Earth observation satellite into orbit.

The launch was delayed several years because of a failure during a previous launch that required a major redesign of an engine. Further delays took place when Avio literally lost the tanks for the rocket’s upper stage, and had to improvise a solution (which has never been explained fully).

The rocket will now be replaced by the Vega-C, which after several more launches will be entirely owned and managed by Avio, which will market it to satellite customers without any significant participation of the government middleman Arianespace.

This was only the second launch by Europe in 2024, so the leader board of the 2024 launch race does not change.

86 SpaceX
37 China
10 Rocket Lab
9 Russia

American private enterprise still leads the rest of the world combined in successful launches 101 to 56, while SpaceX by itself leads the entire world, including American companies 86 to 71.

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Due to thruster problem, the Mercury orbiter BepiColombo will arrive at Mercury almost one year late

The joint ESA and JAXA Mercury mission BepiColombo will now reach its destination eleven months late because its ion electric thrusters are producing less thrust than expected.

The spacecraft is actually made up of two orbiters, one built by the European Space Agency (ESA) and the second built by Japan’s space agency JAXA. During launch and the journey to Mercury each is attached to a third spacecraft called the Mercury Transfer Module (MTM), which has the large electric ion thrusters used for making the mid-course corrections prior to and after each fly-by of the Earth (once), Venus (twice), and Mercury (six) before finally entering orbit around Mercury. It has already completed the Earth, Venus and three Mercury fly-bys.

In April 2024 engineers discovered that during a mid-course correction on April 26st the MTM’s thrusters failed to produce the desired thrust.

Engineers identified unexpected electric currents between MTM’s solar array and the unit responsible for extracting power and distributing it to the rest of the spacecraft. Onboard data imply that this is resulting in less power available for electric propulsion. ESA’s BepiColombo Mission Manager, Santa Martinez explains: “Following months of investigations, we have concluded that MTM’s electric thrusters will remain operating below the minimum thrust required for an insertion into orbit around Mercury in December 2025.”

In order not to lose the mission entirely, the science team has come up with a new trajectory that will have it fly past Mercury on its fourth fly-by on September 4, 2024 only 103 miles above the surface, 22 miles closer than originally planned. This will give it a larger slingshot speed boost to help make up for the under-powered thrusters. It will then make its planned fifth and sixth Mercury fly-bys in December ’24 and January ’25, the adjusted route having it arrive in Mercury orbit eleven months later than planned, in November 2026.

This new plan however means that the pictures taken this week during the Mercury fly-by will provide some nice high resolution details, far better than those produced by the earlier fly-bys.

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Juice completes Earth fly-by, heads for Venus fly-by

Earth as seen by Juice
Earth as seen by Juice during fly-by.
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The European probe Juice yesterday successfully completed a close fly-by of the Earth and was thus successfully slingshoted on its way to its next fly-by, of Venus, on its way to Jupiter.

This fly-by was actually a double event. First Juice zipped past the Moon the day before, coming within 435 miles. Then, only one day later it passed the Earth at a distance of 4,230 miles, thus completing the first dual fly-by of the both the Earth and the Moon.

The flyby of the Moon increased Juice’s speed by 0.9 km/s relative to the Sun, guiding Juice towards Earth. The flyby of Earth reduced Juice’s speed by 4.8 km/s relative to the Sun, guiding Juice onto a new trajectory towards Venus. Overall, the lunar-Earth flyby deflected Juice by an angle of 100° compared to its pre-flyby path.

The inherently risky flyby required ultra-precise, real-time navigation, but is saving the mission around 100–150 kg of fuel. In the month before the flyby, spacecraft operators gave Juice slight nudges to put it on exactly the right approach trajectory. Then they tracked Juice 24/7 between 17–22 August.

The Venus fly-by will occur in August 2025, followed by additional Earth flys in September 2026 and January 2029. The spacecraft will finally arrive in Jupiter orbit in July 2031, where it is designed to study the large icy moons (Europa, Gandymede, and Calisto) of that gas giant.

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Juice completes fly-by of Moon

Juice's view of the Moon
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Europe’s Juice probe to Jupiter yesterday successfully completed its close fly-by of the Moon, shifting its path as it prepares for a close fly-by of the Earth today.

The picture to the right, cropped, reduced, and sharpened to post here, was taken during yesterday’s flyby. At its closest approach Juice was only 435 miles above the lunar surface. It will pass the Earth today at a distance of 4,230 miles.

If the Earth fly-by today is successful, Juice will then do flybys of Venus in August 2025, Earth in September 2026, and Earth again in January 2029, arriving in Jupiter orbit in July 2031, where it is designed to study the large icy moons (Europa, Gandymede, and Calisto) of that gas giant.

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Gaia space telescope identifies more than 350 asteroids with candidate moons

Using the Gaia space telescope, astronomers have identified 352 asteroids that the data suggests have smaller satellite asteroids in orbit around them.

In its data release 3, Gaia precisely pinpointed the positions and motions of 150 000+ asteroids — so precisely that scientists could dig deeper and hunt for asteroids displaying the characteristic ‘wobble’ caused by the tug of an orbiting companion (the same mechanism as displayed here for a binary star). Gaia also gathered data on asteroid chemistry, compiling the largest ever collection of asteroid ‘reflectance spectra’ (light curves that reveal an object’s colour and composition).

These results need to be confirmed by direct observation, as this method does involve some assumptions and uncertainties. If these numbers are confirmed however it will give planetary scientists a better census on the percentage of asteroids with moons, which in turn can be used to create better models of the formation of the solar system as well as the evolution of asteroids over time. At the moment scientists predict about one out of every six asteroids will have a moon. This data suggests that number might be high.

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Arianespace finally schedules last Vega launch

After improvising an upper stage fix because the rocket’s Italian manufacturer, Avio, literally lost the stage’s tanks, Arianespace on July 31, 2024 finally scheduled the last Vega rocket launch, targeting a September 3, 2024 lift off from French Guiana.

The change to the upper stage was required after the company managed to lose two of its four propellant tanks. As the production line for the AVUM upper stage tanks had been shut down in anticipation of the rocket’s retirement, Avio was forced to find a way to instead utilize the larger propellant tanks from the Vega C AVUM+ upper stage. With this process now complete, the company has a clear path toward the rocket’s swan song.

This rocket has been replaced by the more powerful Vega-C. Control and ownership on future launches has also been shifted from Arianespace back to Avio as part of Europe’s transition from using a government-run launch monopoly (Ariancespace) to relying on multiple competitive and independent private companies.

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Astroscale wins contract to deorbit OneWeb satellite

The orbital tug company Astroscale has won a $15 million contract from both the UK and European space agencies to launch a mission to rendezvous, grab and then deorbit a defunct OneWeb communications satellite.

The company, originally from Japan, has established operations in both the U.S. and Europe in order to win contracts from those regions, and had already signed contracts with OneWeb, several UK companies, the the European Space Agency (ESA), and the UK Space Agency for this project. This new contract apparently releases the money from both ESA and the UK.

The mission, dubbed ELSA-M, is will fly no later than April 2026, will be built by Astroscale’s UK division in Oxford, and is a follow-up of the ELSA-d mission that in 2021 demonstrated rendezvous and proximity operations but was unable to complete a docking using Astroscale’s magnetic capture system because of failed thrusters. I suspect the reason this new deal was finally approved is because of Astroscale’s more recent successes in another mission for Japan’s JAXA space agency, ADRAS-J, rendezvousing and flying in proximity to an old abandoned H2A rocket upper stage.

The new mission will attempt once again to prove the practicality of Astroscale’s magnetic capture system, which it is trying to convince all satellite companies to include on their satellites.

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ESA’s Juice probe to Jupiter prepares for first Earth+Moon slingshot fly-by

Graphic showing Juice's upcoming duel fly-by
Graphic showing Juice’s upcoming duel fly-by.
Click for original image.

The European Space Agency’s (ESA) first mission to Jupiter, dubbed Juice (Jupiter Icy Moons Explorer) is about to do the first ever back-to-back fly-bys of the Moon and then the Earth immediately afterward in order to slingshot it forward on its long journey to the gas giant.

The graphic to the right, cropped and reduced to post here, shows the plan. Juice will first fly past the Moon, shifting its path slightly, and then zip past the Earth one day later, its trajectory then under-going a much larger change.

The lunar-Earth flyby will see Juice pass just 700 km [435 miles] from the Moon’s surface at 23:16 CEST on 19 August and 6807 km [4230 miles] from Earth’s surface almost exactly 24 hours later at 23:57 CEST on 20 August.

Using the gravity of the Moon to slightly bend Juice’s trajectory first will improve the effectiveness of the much larger gravity assist at Earth. However, the dual flyby requires extraordinarily precise navigation and timing, as even minor deviations could send Juice in the wrong direction.

The engineering teams have already been doing simulations to make sure they get this complex maneuver right. If all goes right, the spacecraft will then do flybys of Venus in August 2025, Earth in September 2026, and Earth again in January 2029, arriving in Jupiter orbit in July 2031.

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