DEX Antenna Development (2025-2027)
Having antennas of sufficiently low mass is of prime importance to make an array like DEX possible. With at least 1024 antenna elements, deploying an array like this using a single lander means keeping the mass per element to an absolute minimum. The DEX antenna development activity, undertaken by ATG Europe, ASTRON, and Radboud Radio Lab, focuses on the design and production of a prototype sub-array for DEX. The activity includes a re-evaluation of system and subsystem requirements, a trade-off study between array designs, design of the low-mass antenna sub-array with LNAs connected, an evaluation of its performance, and the planning of a development road map towards full-scale DEX. This activity is planned to conclude in October 2027.
GloDEX design study (2025-2026)
In the context of the redshifted cosmological neutral hydrogen signal, measuring the ‘global signal’ refers to recovering the sky-integrated spectral signature from measurements done with individual antennas (i.e., total power measurements). With GloDEX we are interested in performing such a measurement from the Moon’s surface, focusing on the Dark Ages epoch (~7 – 50 MHz). For such a measurement it is of crucial importance to have a highly detailed understanding of the system response, as minor variations in received power with frequency can mask as the science signal and give false results. Predicting the system response in advance without detailed knowledge of the landing site is practically impossible, which is why the GloDEX concept makes use of multiple antennas of different designs. This approach is inspired by that of the REACH experiment, which does this from Earth, for the Cosmic Dawn epoch (~50 – 100 MHz). The GloDEX design study focuses on working out the key parameters for this Moon-based experiment, including the number of antennas involved, the antenna types, the amplifiers, and the way in which this data will be processed. This activity is planned to run until November 2026.
Dark Ages EXplorer (2025)
The Dark Ages EXplorer (DEX) is the flagship cosmology instrument concept within the ALO roadmap. While ALO represents a broad vision for a lunar‑based radio astronomy platform, DEX is the mission’s scientific and technical core, focused on accessing the earliest observable phases of cosmic history.
DEX is conceived as a filled‑aperture, ultra‑long‑wavelength interferometer deployed on the Moon’s far side. Its role within ALO includes:
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Driving the Core Cosmology Mission
DEX provides the sensitivity and architecture needed to detect both the global 21‑cm signal and the angular power spectrum from the Dark Ages and Cosmic Dawn. -
Defining ALO’s Technical Pathway
Requirements for antenna deployment, power systems, calibration, and data processing are shaped directly by the needs of DEX’s cosmology program. -
Offering a Scalable Architecture
Initial deployments may consist of a small array, with future missions expanding the system toward a powerful, full‑scale interferometer capable of high‑fidelity cosmological measurements.Further technical and scientific details about DEX can be found in the published overview paper: https://arxiv.org/abs/2504.03418
ALO/DEX CDF Study (2021)
In May/June 2021, a Concurrent Design Facility (CDF) study was performed by the ESA engineering team in conjunction with the ALO science team. The subject of this study was to work out what low-frequency radio array size would be possible to deploy using a single lunar lander. With current technology, a 4×4-element array would be possible – but for Cosmic Dawn science, a much larger array is needed of at least 32×32 elements. The CDF study thus highlighted the different directions of technology development needed for a cutting-edge facility on the Moon. Below, the public edition of the study report can be perused.