The Space Array initiative and SHARP proposal

The Space Array initiative and SHARP proposal E. Villard and the Space Array & SHARP teams Sub-mm astronomy •Unique window into the cold Universe •Sub-mm frequencies (300 GHz to 1 THz) reveal cold, dense regions of the Universe, crucial for studying star and planet formation. •Sensitive to dust and gas emission •Enables investigation of molecular clouds, protoplanetary disks, and distant galaxies hidden by cosmic dust. •High-angular resolution provides insights into Active Galactic Nuclei (AGNs) and Black Holes •Not just the distant Universe: Solar System objects can also be studied •Study of thermal emission, ices, atmospheric composition and cometary activity 10th International VLBI Technology Workshop - Eric Villard We have only scratched the surface •ALMA and the EHT have enabled breakthrough discoveries in astronomy. •High-angular resolution has revolutionized our understanding of protoplanetary disk formation and black hole physics. •But so far, we’ve only observed the largest and brightest targets. •What are we missing? •How complete is our current picture? 10th International VLBI Technology Workshop - Eric Villard The future of sub-mm astronomy •ASAC recommendations for ALMA 2030 •Improvements to the ALMA Archive: enabling gains in usability and impact for the observatory. •Larger bandwidths and better receiver sensitivity: enabling gains in speed. •Longer baselines: enabling qualitatively new science. •Increasing wide field mapping speed: enabling efficient mapping. •ALMA WSU will provide better sensitivity. As for angular resolution, it will be difficult to do better than the EHT. •Baselines stretch across the globe and atmospheric transmission is decreasing with frequency. •ONLY OPTION IS TO GO TO SPACE •ALMA2040 (European) initiative just started 10th International VLBI Technology Workshop - Eric Villard A very active Space-VLBI community •VSOP (mission flown) •RadioAstron (mission flown) •ESPRIT •Event Horizon Imager •THEZA (concept proposed for Voyage2050) •Black Hole Explorer (concept under development in the US, space-to-ground VLBI) •Capella (concept under development in South Korea, 4 satellites) 10th International VLBI Technology Workshop - Eric Villard The Space Array initiative •Formal kick-off held in December in Gothenburg, funded by Chalmers University of Technology •Group of over 60 participants representing a broad spectrum of expertise, including: •Space VLBI •Sub-millimeter interferometry •Radio receivers and antennas •Data correlation •Satellite navigation •Laser communication •Participants drawn from a diverse range of institutions: universities, public research organizations, space agencies, and the private sector •Many participants have led or played key roles in previous Space VLBI missions and initiatives 10th International VLBI Technology Workshop - Eric Villard Our vision •Large constellation of (cost-effective) satellites working together as an interferometric array. •Unique capabilities: •HIGH FREQUENCY observatory •From 300 GHz up to FIR (mainly limited by antenna quality) •HIGH IMAGING QUALITY •Fantastic uv coverage, thanks to (large) number of satellites and rapid orbital rotation •“It cannot be overstated how crucial the UV-coverage is to the successful imaging of the complex structure of HL Tau.” (ALMA Partnership et al 2015) •Large range of HIGH ANGULAR RESOLUTIONS •MEO altitude provides highest angular resolution. •SLOW DRIFT of array provides varying angular resolution over time (e.g. ALMA configurations) 10th International VLBI Technology Workshop - Eric Villard ESA call for science missions •The ESA call was a fantastic and timely opportunity. •Support from the community has been very enthusiastic. 10th International VLBI Technology Workshop - Eric Villard SHARP proposal •SHARP will be a 3-spacecraft interferometer mission, orbiting at ~8000km around the Earth, with slightly different radii so they drift relative to each other. •Each S/C will have: •a 3.4m CFRP antenna, capable of observing up to 950GHz. •4 receiver bands (20 GHz IF bandwidth): •Band 1: 67-116 GHz (mainly, for calibration of high frequency) •Band 2: 211-373 GHz (general purpose) •Band 3: 560-740 GHz (for BH imaging) •Band 4: 790-950 GHz (for BH imaging at extreme AR, 2.7 uas) •a laser communication terminal, capable of accommodating the highest data rate (240Gbps) •two LCTs, to connect to the other two satellites, and a real-time correlator. •The data streams will be correlated in real time, using an approximate delay model, and accumulated up to a second, to reduce the downlink data rate. •Fine delay corrections will be applied on the ground, using accurate orbit reconstruction (multiple GNSS satellites), fringe-fitting and phase referencing. 10th International VLBI Technology Workshop - Eric Villard