Brighter Days Ahead for Studying Dark Energy

It's official: the Euclid telescope is planned to be launched into space starting on July 1, 2023, to embark on a six-year mission to create the largest, most accurate 3D map of the universe to understand the nature of dark energy and dark matter—and the Euclid NASA Science Center at IPAC (ENSCI) is ready for that launch.

Such an undertaking has required years of careful and thoughtful planning and engineering with contributions from the international science community, including US-based researchers, who will have access to the data and support thanks to NASA’s investment in the mission. ENSCI has been preparing for this moment for more than 10 years.

"ENSCI is excited to bring to the table decades of experience serving as the science center for NASA missions, and for ESA missions with NASA involvement," said Dr. Harry Teplitz, ENSCI Task Lead. "We hope this will enable unique contributions to the Euclid mission."

Caltech/IPAC’s experience with supporting international collaborations between NASA and ESA includes having served as the US science center for the Herschel, Planck, and Infrared Space Observatory (ISO) missions.

Teplitz said Caltech/IPAC is also applying lessons learned from the Planck mission related to transferring data from Europe to California for data processing.

"IPAC has developed a well-tested set of best practices to efficiently contribute to European-led projects," said Teplitz. "IPAC has been able to leverage the difference in time zones to increase project staff availability during crucial mission phases; that is, we effectively have two work days within each 24 hours, one in Europe and one in the US. Through these many projects, IPAC has formed enduring relationships with scientists, engineers, and project managers in Europe, many of whom are now involved in Euclid."

"Ultimately, our goal is to support the US-based scientific community more broadly in accessing, analyzing, and utilizing the data and getting science done."

- IPAC Director George Helou

How Caltech/IPAC Is Supporting Euclid

NASA’s investment in Euclid is an investment in supporting the US astronomical community. NASA funded the telescope’s 16 near-infrared detectors and associated cables and electronics, and is hosting one of 11 nodes distributed around the world that comprise Euclid’s Science Ground System (SGS). ENSCI, which is located on the California Institute of Technology campus in Pasadena, California, operates the US Science Data Center (SDC-US) for data processing. Each node in the distributed system is capable of running the full pipeline so that large data volumes do not have to be frequently transferred. Euclid is expected to generate petabytes of science data; the SDC-US will manage about 5% of the full distributed system.

ENSCI scientists and software engineers have developed and delivered several modules for the near-infrared data pipeline, which the SGS integrated into the full pipeline.

In addition to providing software that goes into the pipelines that process, calibrate, and extract data from Euclid imaging and spectroscopy, ENSCI has been holding meetings with US science teams several times per year and also giving webinars and talks at astronomy conferences to engage the broader community. In May, ENSCI hosted a meeting at Caltech/IPAC for US-based members of the Euclid Consortium (EC). 

ENSCI’s website provides news and background information about the mission, links to other Euclid resources, and will soon publish explanatory documentation and video tutorials. ENSCI also operates a Help Center to respond to questions about the mission.

"Ultimately, our goal is to support the US-based scientific community more broadly in accessing, analyzing, and utilizing the data and getting science done," said Caltech/IPAC Director George Helou.

A Stateside Science Data Archive Means Faster Access

Caltech/IPAC is also charged with setting up NASA’s official science archive for Euclid data, which will be integrated into the Infrared Science Archive (IRSA). IRSA will serve the same public data products found in ESA’s primary archive at ESAC in Spain on the same schedule, served with user interface features targeted to the needs of the US community while providing faster access to US-based researchers because the data are geographically closer.

Euclid will have annual data releases starting in late 2024, beginning with a "Quick Release" that offers a preview of 50 sq. degrees of surveyed sky. The first major data release, expected in late 2025, will include data acquired in the survey’s first year, followed by alternating quick and major data releases.

"Scientifically, Euclid’s data set fits very naturally within the breadth of existing and planned multi-wavelength, large-area surveys at IRSA," said Vandana Desai, IRSA Science Lead, noting that IRSA has already developed in-house expertise on managing big data archives from the Wide-field Infrared Survey Explorer (WISE) and Zwicky Transient Facility (ZTF) surveys.

"One of Euclid’s strengths is the science potential of its enormous multi-petabyte imaging archive; another strength is the richness of information in the tens of millions of spectra that Euclid will provide," said Desai. "From a technical point of view, there are strong synergies between the large spectroscopic archives from Euclid and SPHEREx, which will also be released through IRSA in a similar timeframe. IRSA is leveraging these synergies to more efficiently provide the community with interoperable archive tools that allow users to scientifically mine giant spectroscopic data sets."

"A survey covering a third of the sky with exquisite accuracy and detail is certain to yield unexpected and ground-breaking science results in areas other than dark energy and dark matter," said Helou. "IRSA and ENSCI are looking forward to supporting the community in extracting that science from the Euclid archive."

Euclid Fast Facts

• 1.2-meter telescope with two instruments: optical camera (0.5-0.9 microns) and near-infrared camera/spectrometer (0.9-2 microns)
• Will examine 10 billion years of cosmic history and create a 3D map of the universe to understand the nature of dark energy and dark matter
• Will survey more than 33% of the sky
• Six-year expected lifetime
• Scheduled to launch at 8 a.m. PDT/11 a.m. EDT Saturday, July 1, 2023
• ENSCI website: https://www.euclid.caltech.edu

Active Participation in the Euclid Consortium

Caltech/IPAC staff are also participating in the activities of the Euclid Consortium, an organization of roughly 2,000 scientists in 17 countries in Europe, the US, Canada, and Japan.

"Caltech/IPAC scientists have made significant contributions to Euclid science," said Dr. Yun Wang, IPAC scientist and Deputy Coordinator of the Euclid Consortium Galaxy Clustering Science Working Group (GC SWG), one of the two major Euclid SWGs. Wang led the early forecasts of the dark energy constraints from Euclid galaxy clustering data and helped define science requirements for the Euclid mission. "A research group led by IPAC scientist Dr. Ranga-Ram Chary, Principal Investigator for one of the three Euclid science teams in the US, showed that the use of NIR images leads to the enhancement of dark energy constraints from Euclid weak lensing," said Wang. "IPAC scientists Drs. Peter Capak, Dan Masters, and Shoubaneh Hemmati developed self-organizing maps as an effective way of estimating photometric redshifts, key to Euclid weak lensing science." Wang’s research group also made key contributions to Euclid galaxy source count predictions, realistic galaxy mock-catalog simulations, and the modeling of observational systematic effects.

How ENSCI’s Role Will Evolve After Launch

It will take Euclid one month to arrive at the second Lagrange point, or L2—one of five locations in space where gravity and orbital mechanics align to be great spots for spacecraft to "park" and observe the larger universe.

Once there, the mission will have a two-month check-out phase, called Performance Verification. ENSCI will participate by supporting the validation of data products produced by processing new observations with the software modules that ENSCI delivered.

When routine operations start, ENSCI will be a node in the distributed data processing system.  Data will need to be processed every day during Euclid’s six-year mission. Software modules will need to be updated, as all missions find that real data are at least slightly different than predicted, so ENSCI’s scientists and software engineers will respond with the required modifications.

Most importantly, ENSCI support of US-based investigators will ramp up significantly once routine operations start, and especially once data are released to the worldwide community in large installments. Over the first several years of the mission, especially after Data Release 1, the ENSCI workforce assignments will shift to focus primarily on user support.

The Euclid spacecraft is scheduled to launch from Cape Canaveral, Florida aboard a SpaceX Falcon 9 rocket at 8 a.m. PDT/11 a.m. EDT Saturday, July 1, 2023. Watch a livestream of the launch on NASA Live or ESA Web TV.