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Euclid still had small problems.  But we are trying to solve it

Euclid still had small problems. But we are trying to solve it

Between July and August, the Euclid Space Telescope went into good operation. The first weeks of tests, calibrations and maneuvers after placing the telescope at the L2 Lagrangian point, 1.5 million kilometers from Earth, gave positive results. The first test images seem to indicate that the next stage is one AssignmentIt would have been successful.

But unfortunately, at least Three important problematic issues They forced the mission team to do extra work. Orientation sensors intermittently lose track of sources, scattered sunlight hampers monitoring, and X-rays appear in instrument images. These problems ESA teams aren’t too concerned about the mission’s outcome, But it may affect the actual work being done in space, or at least timelines.

One: unwanted stray light

Euclid in orbit aura Around the Lagrange point L2 with its back to the sun, all the most sensitive parts of the satellite and telescope are protected from sunlight by a special screen. However, it was known that the fan stand was located outside the sun’s shadow and would receive direct sunlight.

A small amount of sunlight appears to be coming from this direction It reflects from the arc of this support towards the VIS instrument (Visual tool). Although they are protected by many layers of insulation, due to their extreme sensitivity, some sunlight passes through them as scattered light. This was discovered in test observations when the VIS was rotated to specific angles.

Effects of scattered light on test observations made with a Euclid VIS instrument placed at different angles. Credits: European Space Agency

Most VIS observations showed no noticeable light interference, but only at certain angles Approximately 10% of observations were affected.

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Several teams spent weeks deciphering which angles let in a lot of unwanted light, and they did Redesigned and improved Euclid detection To constrain the direction of each point in the sky. While this does not affect Euclid’s ability to capture the exact images required, it may affect its efficiency. This potential effect is still being studied.

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Second: Losing scoring

The Euclid mission is one of the most precise missions ever launched, and is equipped with a Fine Guidance Sensor (FGS) entirely developed in Italy by Leonardo. This is a brand-new instrument in Europe, made up of optical sensors that identify the same sources found by the European Space Agency’s Gaia mission, and uses them as a guide to navigate and determine exactly where the telescope should be pointing in the sky. This information is entered inAttitude and orbit control systemWhich controls Euclid’s direction and orbital motion.

While most systems worked well, there were intermittent instances where the sensor worked well Failed to detect faint stars.

In orbit, Euclid discovers the real sky in real space conditions, something that is very difficult to simulate before launch. Moreover, cosmic rays from the Sun and the Galaxy contaminate observations, making the FGS’s work a real challenge.

Therefore, the Euclid run phase was extended to investigate the problem, delaying the run phase Assignment To check performance. Since then, the teams have been working on a software solution that has now been released and is currently undergoing extensive testing.

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First test images from the NISP (left) and VIS (right) instruments of ESA’s Euclid Space Telescope. Source: ESA/Euclid/Euclid Consortium/NASA

The updated software has already successfully passed a spacecraft simulator and a replica of Euclid on Earth at the European Space Agency’s Mission Control Center. So far, all the evidence makes scientists, engineers and technicians optimistic. “We will continue to keep our fingers crossed. But the resumption of the performance verification phase is getting closer every day,” said project manager Giuseppe Racca.

Third: X-rays from the increasingly active Sun

Stray light was not the only sun-related problem that Euclid found himself facing. In fact, solar activity is currently high: the Sun is approaching the peak of maximum activity of the cycle, expected between 2024 and 2025. This leads to an increase in the number Solar flaressudden bursts of electromagnetic radiation from the surface of the Sun.

It appears that at certain angles, X-rays emitted by the Sun during flares can sometimes reach Euclid’s detectors, ruining some of the images taken at the time.

The analysis currently predicts that, depending on solar activity, Euclid may lose about 3% of its data If this issue is not addressed. Currently, the teams are analyzing test images to identify affected pixels, discarding them in subsequent analyses, and working on a plan to fill gaps like these in the Euclid cosmological survey.