Soon following launching on 1 July, the European area observatory Euclid started undertaking small, surprising pirouettes. The issue unveiled alone throughout initial exams of the telescope’s automatic pointing technique. If still left unfixed, it could have severely influenced Euclid’s science mission and led to gaps in its map of the Universe.

Now the European Room Agency (ESA) suggests that it has fixed the challenge by updating some of the telescope’s computer software. The difficulty occurred when the on-board pointing procedure mistook cosmic sounds for faint stars in dark patches of sky, and directed the spacecraft to reorient alone whilst capturing a shot.

Giuseppe Racca, Euclid task supervisor at ESA in Noordwijk, the Netherlands, says that the updated pointing program will work a little bit slower than planned. As a end result, the key mission, owing to final six a long time, could acquire up to six months more time. Its scientific objectives should really not be influenced, ESA claims.

Mapping the Universe

Euclid is designed to have out a deep survey of the Universe by mapping the positions of 1.5 billion galaxies in 3D, searching beyond the stars in the Milky Way. But to do so, it will frequently have to photograph some of the darkest patches of the sky, which have only really faint stars. Euclid ought to use the known positions of those people stars — as formerly mapped by a further ESA mission, Gaia — to discover the appropriate patch and continuously alter its posture to exceptionally large precision for additional than 10 minutes at a time.

Original tests of this procedure confirmed that, in some conditions, the telescope was not pointing stably. Instead, it would wobble, generating take a look at images in which some stars appeared to adhere to little looping trails.

ESA says that the Euclid team, collectively with its principal industrial contractor, Thales Alenia Place, was equipped to diagnose the issue promptly. The pointing method utilizes auxiliary sensors inside the telescope to consider periodic 2-2nd exposures of the field of perspective. It then matches the stars it sees with people in the Gaia catalogue, to make sure they are in the predicted positions. But the sensors also decide on up sounds from energetic particles these as cosmic rays, which constantly rain onto the probe from all directions, explains Giovanni Bosco, a physicist at Thales Alenia Space in Turin, Italy. In just 100 milliseconds, the on-board software has to filter that noise and one out the true stars.

This did not generally do the job out as prepared, suggests Racca. “Sometimes it had as well several stars, and it was finding puzzled. It was getting rid of the guiding stars and then automatically started to appear for them once again.”

Bosco labored with the team at subcontractor Leonardo in Florence, Italy, to correct the dilemma by increasing how the algorithms filter out cosmic sounds. ESA has now examined the method and announced on 5 October that it is operating as planned.

Rogue light

Yet another issue spotted in early imaging exams was that little quantities of stray light-weight seemed to be getting into the telescope — despite it currently being guarded by a sunshield and wrapped in various levels of insulation. The challenge was most likely induced by a thruster that sticks out to 1 side of the spacecraft, wherever it is not safeguarded by the sunshield, states Racca. When the telescope was oriented at selected angles, daylight was ricocheting off a 1-sq.-centimetre location on the thruster — the only portion of it that is not painted black — and bouncing from the again of the sunshield on to the facet of the telescope. A compact fraction of this mild could be detected by Euclid’s super-sensitive cameras. The mission staff found that the difficulty went away after merely modifying the orientation of the probe by 2.5 degrees.

Racca states that the mission can now resume its prepared commissioning phases, and expects that it will be equipped to start out its scientific operate some time in November.

“When I read about the troubles and the options they ended up attempting out, to me it sounded like this will do the job out,” says Anthony Brown, an astronomer at Leiden University in the Netherlands and a senior member of the Gaia science crew. Even now, he adds, every time troubles with a room mission can be conquer, “it’s always an immense reduction.”

This write-up is reproduced with permission and was initial posted on Oct 6, 2023.