Update from the Euclid Project Scientist

Mosaic of nearby galaxies as seen by the Hubble Space Telescope

Updates and thoughts from the Euclid Project Scientist

René Laureiijs (ESA Project Scientist), March 2023

Finally, we now have a very firm launch interval, and it is approaching with light speed! We still have to tick off many boxes for the science operations, where a number of key operational activities must be defined in necessary detail. There is a large amount of work to be done related to the preparations for scheduling, processing, and analysis of the scientific (calibration) observations before the start of the Euclid survey. The daily science data rate in orbit will be huge and the timescales between the milestones are short, shorter than the time required to train completely new personnel. With a positive attitude, well-prepared teams, and good organisation we can meet our goals. There is certainly no lack of collaborative spirit and no fear of challenges, inherent to our ambition to break new scientific ground.

Launch approaching

While I am writing this, Euclid arrived at the Port of Savona via road transport a few days ago. Euclid is poised for a trip by boat from Italy to Cape Canaveral for a Falcon 9 launch. SpaceX aims to achieve one successful launch at an incredible rate of every 4 days, which raises the sobering thought that we are just another customer in their long list. Euclid has entered a new space age where space is more accessible and a more common element in our lives. This was already predicted in the sixties during the Apollo programme, but only now it takes off. Euclid will be part of this by enabling scientists easy access to the entire extragalactic deep sky.

Euclid’s trip to L2

Euclid’s trajectory will be a direct orbit injection: after separation from the second stage of the Falcon 9 rocket, Euclid will fall in the SEL2 potential well to a halo orbit without the need for an additional orbit insertion. A few days after launch the mission starts with the spacecraft commissioning phase, where industry will ensure that the spacecraft and all its subsystems are ready for the in-orbit operations. During this phase the payload will also be decontaminated and cooled down. No science operations are planned, but the VIS instrument will generate science data for the telescope focussing procedure. The first Euclid image will probably a dense stellar field in the outskirts of the Large Magellanic Cloud close to the ecliptic south pole which has perennial Euclid visibility.

Early Release Observations

One month after launch we will start with a two-month performance-verification (PV) phase reserved for the scientific component of the mission. We will determine the in-orbit performances of the science supporting systems to check if all our expectations can be met. ESA, and in particular the project team, want to have the confirmation that all essential elements are performing according to the mission requirements. If needed the survey plan will be adjusted for the in-orbit performances.

Of the 60 days of PV phase, we will allocate one day for Early Release Observations. The ERO programme aims to collect competitive scientific observations with a high outreach and communications merit. As a rule of thumb Euclid is able cover in one day some 10 deg2 of sky with the Reference Observing Sequence (ROS). These 10 degrees should be compared with the ~30 deg2 mapped by HST so far. Following a call to the Euclid Science Collaboration we received 12 ERO proposals. The ERO Program Committee is presently evaluating the proposals. The selected observations will feature in a media event, planned to be held some 4 months after launch. Besides the communication products, ESA will release the scientific data to the public, after scientific validation by the proposing teams.

Logistic challenges at launch

But first Euclid must be launched. This is a serious logistic challenge, including the preparations of the ground stations to track Euclid. The ESA communications teams are doing their best to organise the media coverage from Cape Canaveral without the leading support from NASA, which is a new experience outside ESA’s spaceport in Kourou. Many people are planning to travel to Florida and watch the launch in the morning around 11:00 local time, this leaves us plenty of time for a beach party afterwards that day. We should not forget our colleagues at ESOC (Darmstadt) who will be already busy with the Low Earth Operations Phase. Let us cross fingers for a successful Falcon 9 launch to the second Sun-Earth Lagrange orbit

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