Final Cluster reentries – Live blog – Rocket Science

This final Cluster reentries live blog provides the latest updates by ESA on the reentry of Samba (CLU3) and Tango (CLU4).

This live blog has now closed, the page was updated until after both reentries had taken place, with the latest entry at the top.

3 Sept 9:30 CEST – first footage

The team can look back on a very successful observation campaign. We have video footage of Samba streaking across the sky to share below, while a total of 29 of the 30 instruments onboard were able to capture the reentry of both Samba and Tango.

Check out the article on the ESA website for details on how Cluster’s encore is a success for reentry science.

2 Sept 00:15 CEST – Success confirmed plane campaign

The ROSIE team has reported from the plane on their way back to Tonga: “SUCCESS – we confirm visual on almost all cameras.”

We now have to wait until they get back and can transmit data, including the first image we can’t wait to see. Expect an update on this here tomorrow, including video footage from Samba!

1 Sept 23:40 CEST – Reentry confirmed

And then there were none…

Tango has danced its final dance and reentered the atmosphere at 21:30:31 UTC/ 23:30:31 CEST.

The very last signal from the spacecraft Tango, from all of the Cluster mission, came in via Kourou ground station and then was lost forever at 23:26 CEST.

1 Sept 21:30 – ROSIE team en route to Tango

There they go, the ROSIE team is once more on its way with all their instruments to observe a Cluster reentry in this final act with Tango. Go, team, go!

You can follow them here: https://www.flightradar24.com/4175e317

The ROSIE team leaves Tonga to observe the final reentry of Cluster. Credit: Astros Solutions/ROSIE

1 Sept 13:10 – Samba streaks fiery across the sky

Samba’s reentry was recorded, experiment successful! There is fire streaking across the sky in this first image from the ROSIE airborne observation campaign. The team is flying out again today for Tango’s reentry, with the promise of video footage once they’ve completed their task.

Congratulations to the ROSIE Samba & Tango team as well as all the ESA teams from flight dynamics to space debris, operations and even planetary defence that made this success possible!

Read more in the news article on ESA’s website.

1 Sept 10:45 CEST – Time to Tango

As we wait until we can share the first image from Samba’s demise today, the final reentry time prediction was confirmed for Tango.

Later today, Tango will reenter the atmosphere at 21:30:31 UTC / 23:30:31 CEST, with an uncertainty remaining of +/- 1 second either way.

1 Sept 00:15 CEST – Success confirmed plane campaign

The ROSIE team has reported from the plane on their way back to Tonga: “SUCCESS – we confirm visual on all tracking cameras.”

We now have to wait until they get back and can transmit data, including the first image we can’t wait to see! Expect an update on this here tomorrow.

31 August 23:45 CEST – Reentry confirmed

Samba has danced its final dance and reentered the atmosphere at 23:39:38 CEST.

The final signal from the spacecraft signal coming into Kourou was lost for the very last time at 23:26 CEST.

31 August 19:55 – Cluster’s last dance

The official end to the Cluster mission was in 2024. Yet today and tomorrow, its community is gathering for the ‘Cluster’s last dance’ event (Cluster SWT # 61) at ESOC, ESA’s European Space Operations Centre in Darmstadt, Germany.

The scientists once more discuss the data the mission gathered, reminisce and, joined by other interested people from the ESOC workforce and beyond, watch the Cluster documentary Seas of the Sun: The story of Cluster, letting the live music roll over them. Finally, they will stay for Samba final act today, Tango’s tomorrow, the last pass, the last loss of signal and confirmation of their reentry…

31 August 15:25 – Planetary defence support

If they move like asteroids, why not get asteroid hunters to help out? Thankfully, we have a number of them around in our Planetary Defence team, happy to support the tracking of Samba and Tango along the trajectories so similar to those of near-Earth objects.

The team has observed both Samba and Tango with ESA’s Optical Ground Station, located in Tenerife (Spain). In the GIF you can see Tango (CLU4) streak across a background of stars. It was taken as the satellite was moving away from Earth after going through its last perigee pass, because as it won’t experience the effect of the atmosphere until its reentry approach, the re-entry location and time can be determined very accurately, especially when then combined with data from other sources.

31 August 11:45 CEST – Reentry times

With orbital data from the last ground pass on 30 August and additional tracking from ground-based telescopes, we expect Samba’s reentry tonight, 31 August at 21:39:38 UTC / 23:39:38 CEST with just +/- 10 seconds of uncertainty left.

For Tango, we now expect its reentry tomorrow, 1 September at 21:30:31 UTC / 23:30:31 CEST with the uncertainty currently at +/- 1 minute, which is expected to be refined even further as it gets closer.

31 August 11:25 CEST – Data from both, check!

The Cluster flight control team and space debris colleagues had a tense few minutes as they waited to see if Tango survived its last perigee pass as well as Samba has. As it came into reach of the Villafranca 2 ground station, Tango did not communicate as it should have, leading the team to expect it had gone into safe mode. It had, but thankfully, the satellite managed to reboot itself a final time and sent on its telemetry.

The data collected on the last perigee passes by both Samba and Tango are very useful in two ways:

Orbit determination: The team can determine the exact orbits of the satellites based on the tracking information, using the range and angles of the origin of their signals – as it has been done throughout the mission of Cluster by our Flight Dynamics team. Together with the orbit determination based on observations from different telescopes around the globe (see below), we can check the consistency of the predictions. Combined, they give the certainty where exactly to send the plane so the ROSIE team can observe the reentries.

Understanding the interaction with the atmosphere: The telemetry (the satellite’s reporting on its health and status, incl. temperatures of different instruments and small changes in its orientation caused by its environment) collected at these low altitudes of 123 and 130 km can help us understand how the atmosphere interacts with the satellites at these altitudes. The data collected at such low altitudes help to prepare for future reentries and for satellites possibly flying in very low low-Earth orbits (VLEO). 

30 August 19:45 CEST – reentry time

With orbital data from the last ground pass today and additional tracking from ground-based telescopes, we expect Samba’s reentry on 31 August at 21:39:54 UTC / 23:39:54 CEST, with +/- 1 minute of uncertainty.

30 August 15:30 CEST – Samba’s last perigee pass

Last night, the flight control team received confirmation from Samba (CLU3) that it has survived its very last perigee! This means that after decades of flying, the satellite managed to withstand the friction at its lowest point at 130 km altitude, the heat that comes with it and managed to power back up after.

As Samba is still speeding away from Earth for the last time, the team is now waiting to see if Tango can also survive its lowest point during its final perigee pass before its reentry.

30 August 14:45 CEST – making observations

The ROSIE airborne observation campaign needs to most precise location possible to line up the plane and the science instruments perfectly to observe the two reentries.

To complement the spacecraft radiometry and increase precision, observations are also done with telescopes. Samba and Tango are the subject of a monitoring campaign by the Inter-Agency Space Debris Coordination Committee (IADC), asking international partners to support the monitoring of the satellite reentry and share data.

The National Space Facilities Control and Test Center of the State Space Agency of Ukraine caught Samba streaking across the skies in August. Credit: NSFCTC of the SSAU.

The Cluster satellites move quite far away from Earth during their 2.5 day orbits, slinging away about 130.000 km at the farthest point. As a result, their asteroid-like behaviour makes observing the satellite to determine its precise location and trajectory the ultimate job for our in-house asteroid hunters within ESA’s planetary defence team.

The National Space Facilities Control and Test Center of the State Space Agency of Ukraine also observed Tango streaking across the skies in August. Credit: NSFCTC of the SSAU.

The team already observed Samba and Tango with ESA’s Optical Ground Station, located in Tenerife (Spain), and the Schmidt telescope at the Calar Alto Observatory (Spain) and are aiming for even more. They’ll keep an eye out during these very last days before reentry and help pinpoint even more precisely the location and time of reentry for the airborne observation team flying out from Tonga.

30 August 10:00 CEST – reentry times

With orbital data from their last ground passes on 28 August and additional tracking from ground-based telescopes, we expect Samba’s reentry on 31 August at 21:41:54 UTC / 23:41:54 CEST, with currently +/- 10 minutes of uncertainty. Tango will follow almost 24 hours later on 1 September at 21:33:20 UTC / 23:33:20 CEST, also with a +/- 10 minute uncertainty.