News - 26-Mar-2021

OASIS: a Far-Infrared Space Mission

(The same article was published at SRONieuws, March 2021)

OASIS is een missieconcept dat een droom waar kan maken voor submm/ver-infrarood sterrenkunde: hoge-resolutie imaging van bijvoorbeeld water op te sporen op asteroïden of in bewoonbare zones van exoplanetenstelsels. Terwijl in het verleden geprobeerd werd dit te verwezenlijken door interferometrie vanuit de ruimte zo als bij de Westerbork Radiotelescoop vanuit de aarde en dit als te duur werd bevonden, is het revolutionaire nu om een opblaasbare spiegel de ruimte in te brengen met een diameter van maar liefst 20 meter. Vergelijk dit met de James Webb ruimtelescoop die een diameter van ‘maar’ 6 meter heeft. OASIS zal later dit jaar voorgesteld worden als een MIDEX-missie van NASA. SRON is door OASIS-PI Chris Walker (Universiteit van Arizona) gevraagd om tegen betaling 3 HEB mixer detectoren te bouwen.

OASIS sounds like a truly dream space mission for the sub-millimeter (Submm) and far-Infrared (FIR) space instrumentation community because it can offer a huge telescope of 20 meters in diameter, and because it is at a fraction of the cost of a traditional telescope. The large size of a telescope is in high demand for Submm and FIR wavelengths since we would like to resolve the observed objects spatially. The so-called spatial resolution is fundamentally limited by the size of the telescope. For the larger wavelengths of the radiation, a larger aperture of the telescope is a must, which is imposed by the law of optical diffraction. Additionally, a larger telescope can also collect more photons, increasing the signal to noise ratio. The Herschel Space Telescope, launched by ESA in 2009, has a diameter of 3.5 meters, which is limited by the launching rocket. To go beyond the Herschel telescope size, one needs a different configuration of a telescope than the James Webb Space Telescope (JWST), which has an effective diameter of 6 meters, but cost 9-10 billion US dollars, which is truly an astronomic number.

Figure 1: Inflatable Mylar balloon-based OASIS telescope concept design and configuration. It makes use of the heritage of the earlier IAE mission. The super large (20-meter) Hencky reflector is compared to the JWST. (credit:

OASIS stands for “Orbiting Astronomical Satellite for Investigating Stellar Systems”, which is a mission concept, to be proposed to NASA at the end of 2021 in response to the Astrophysics Medium Explorers (MIDEX) Announcement of Opportunity (AO). The cost cap will be 290 M$. If all is going well, the launch date will be around 2028. It will be operated in a Sun-Earth L2 halo orbit. The targeted mission life time is not less than 2 years.

OASIS is originally going to employ a 20-meter inflatable aperture with heritage from the Inflatable Aperture Experiment (IAE) mission, which demonstrated in-orbit deployment of a 14-meter aperture system and is shown in Figure 1. OASIS plans to utilize a Hencky reflector geometry together with proven adaptive optics techniques to yield a wide-field-of-view inflatable Mylar mirror operating. The key structure of the telescope consists of three struts with filled tubes, and an inflated support ring. The mirror (or antenna) consists of an inflatable Mylar based disk, where one side is a clear Mylar layer, while the other side is metalized Mylar that acts as the mirror.

A new idea for OASIS is to apply a flight-proven deployable mesh reflector with an aperture size of 20 meters to be developed by a US company (Northrop Grumman). Their designs are scalable, inherently stiff, incredibly light with unmatched surface accuracy, and free from the so-called Passive Inter-Modulation. Figure 2 shows the reflector structure, a drum like structure, fully deployed and latched. This family of deployable mesh reflectors have extensive flight heritage with 100% on-orbit success. Such a reflector surface structure has been good to detect radiation up to 50 GHz. However, for submm and FIR radiation targeted by OASIS, the mesh surface is too coarse to meet the science goals. So, as the latest development, OASIS will apply a Northrop Grumman’s deployable reflector structure as shown in Figure 2, but the Hencky reflector will apply the inflatable disk with metalized Kapton, similar to IAE (shown in Figure 1). The reflector looks really huge, but it is supposed to be small/compact before and during the launch since all the unfold structures of supporting struts and truss rings are stowed.

Figure 2: an example of deployable mesh reflector technology from Northrop Grumman. However, OASIS, at the latest design, will change the mesh reflector with an inflatable Kapton balloon-based configuration. (credit:

The instrument will consist of heterodyne receivers, which are similar to the receivers in HIFI of the Herschel Space Telescope, to cover four frequency bands from roughly 500 GHz to 5 THz. Band 1, which is frequency tunable, is to cover a few lines of HDO, H2O, 13CO. Band 2 is to detect H2O line at 1.67 THz. Band 3 is for the HD line at 2.68 THz, and Band 4 for H2O at 5 THz. The baseline of the detectors for Bands 2-4 will be the NbN hot electron bolometer (HEB) mixers, the same as used for the GUSTO project, for which SRON together with TU Delft has delivered three flight HEB arrays. The University of Arizona (PI institute) and NASA consider the Heritage of the GUSTO technology to be essential for OASIS. Prof. Chris Walker (PI) has invited SRON to contribute the HEB mixers. To get the utmost out of the OASIS mission, it will be really interesting if one could take advantage of a so-called dual polarization mixer by introducing a novel antenna configuration on chip although with the same detector technology. Such a mixer acts as two conventional mixers. Thus, OASIS will effectively collect a double amount of science data or effectively double OASIS mission life time.

OASIS will observe the universe using wavelengths that would allow it to detect the presence of water in deep space. It can help locate water-rich asteroids within our solar system, or help detect water in the habitable zones of other solar systems. There is also the prospect to detect gaseous water near the stars in protoplanetary systems, which might explain the mystery of how Earth came to be covered with so much water. The OASIS science team is preparing more science topics, which OASIS might be able to address. Frank Helmich from SRON and Prof. Xander Tielens from Leiden University, representing the Dutch astronomers, are part of the team.

After Herschel, people believed that having a space interferometry mission is the only way to go, but it is too expensive and also too challenging technically to realize. OASIS opens a new avenue towards FIR space science and is game-changing. OASIS offers a dream project for SRON and also for those who have contributed heterodyne technology development in the past many years. The University of Arizona plans to cover the cost of building the mixers at SRON, in the same way as for the GUSTO project.

Jian-Rong Gao

Latest news items.

  • News - 13/06/2024

    The discovery of an old Microscope

    In the back of a cupboard of our group, (Optics Cluster at the Imaging Physics department of Applied Sciences), a box full of interesting objects had been hiding for almost thirty years. ...

  • News - 13/06/2024

    Interview Joseph Braat, former Professor

    Our Post-doc Yifeng Shao has invited our former Professor, Joseph Braat, for an interview published on Advanced Photonics to look back at his career, the development of optical storage and ...

  • News - 09/03/2023

    First course and agenda for Lifelong Optics Learning

    The first lesson of the basic course on Optics for the Lifelong Optics Learning has been given yesterday. The agenda for the other lessons can be found here. ...

  • News - 23/01/2023

    In Memoriam: dr. Jeff Meisner

    Jeff Meisner, postdoc in the Optics Group of the Department of Imaging Science, has passed away on January 1st.  Jeff became severely ill one year ago.  The medical doctors considered his condition at the ...

  • News - 13/01/2023

    A glance at our Carla Camp

    If you could not join our Carla Camp last year, and whish to know more about it, you can take a glance at the video we made that encapsulate the moment in ...

  • News - 10/01/2023

    Dr. Aurèle ADAM winner of the Westerdijk Prize

    Aurèle Adam (right), Assistant Professor from the our group and Program Director of the Applied Physics Master, has been awarded the Westerdijk Prize by Timon Idema (left) head of the Prize committee ...

  • News - 10/01/2023

    Happy New Year 2023

    We are glad to welcome a new year full of science and wonders. The TUDelft university has been keen to make a promotial video thanking everyone beyond the scene for 2022. We ...

  • News - 15/12/2022

    Two NWO Perspectief Proposal granted for our group

    NWO has granted two Perspectif program proposals where our group is part of: Leading by light guidance, where the university of Twente is leading and Imaging at the smallest scales where our Department ...

  • News - 05/12/2022

    OSA ‘Photo of the Year’, second place for Sven Weerdenburg

    Our Phd student, Sven Weerdenburg made a photo of our high harmonic generation EUV light source which has made it to the 2nd place of Optica (OSA) 'Photo of the Year' contest. A ...

  • News - 11/11/2022

    Face2Phase 3rd edition November 7-9, 2022 in Delft

    The conference addressed phase information in imaging with topics such as lensless imaging, phase retrieval, adaptive and active optics, ptychography, holography, tomography. We also had the honour to have 14 invited speakers ...

  • News - 04/10/2022

    Wenye Ji invited speaker OPL-2022 conference

    Wenye Ji has been invited to give a talk at the OPL-2022 conference in November this year. ...

  • News - 14/07/2022

    Our colleague Aurèle ADAM is the new director of studies for our master program

    Starting from the 1st of August, our colleague Dr. Aurèle ADAM will be the new director of Studies of our master program Applied Physics. He is replacing Prof. Jos Thijssen from the ...

  • News - 29/04/2022

    CARLA Camp 31 May & 1 June 2022

    Together with the industrial and academic photonics communities, we are creating inclusive pan-European photonics career camps aimed at university students and early-stage researchers (graduates, undergraduates, Master’s students, PhD students and early stage post-docs) ...

  • News - 11/02/2022

    Omar El Gawhary appointed as member of the Council of Experts on National Measurement Standards

    Since February 2022, Omar El Gawhary, from the Optics group of ImPhys, has been appointed as member of the Council of Experts on National Measurement Standards (Raad van deskundigen van de nationale ...

  • News - 09/12/2021

    New superconducting material raises the operating temperature of space detectors

    Superconducting niobium nitride (NbN) hot electron bolometers (HEBs) are so far the most sensitive heterodyne detectors for high-resolution spectroscopy at supra-terahertz frequencies (1 - 6 THz). They take advantage of a local ...

  • News - 26/03/2021

    OASIS: a Far-Infrared Space Mission

    (The same article was published at SRONieuws, March 2021) OASIS is een missieconcept dat een droom waar kan maken voor submm/ver-infrarood sterrenkunde: hoge-resolutie imaging van bijvoorbeeld water op te sporen op asteroïden of ...

  • News - 05/03/2021

    Lifelong Optics Learning, educatie platform voor professionals in optica en fotonica

    For English see belowImage from Dutch Optics Centre websiteHet Dutch Optics Centre (DOC), een samenwerking tussen de Technische Universiteit Delft en TNO, heeft het Lifelong Optics Learning opleidingsplatform opgezet voor professionals in optica ...

  • News - 03/03/2021

    World-record in single-photon detection efficiency has been achieved by TUDelft team in Optica/Imphys (Editor’s Pick in APL Photonics)

    Detecting light at its quantum limit -single photon-level has enabled and greatly benefited quantum information sciences, fluorescence imaging, Lidar (radar with light), and many other applications. Since 2001, superconducting nanowire single photon detectors ...

  • News - 12/01/2021

    EMPIR project funded

    The project proposal POLight (Pushing boundaries of nanometrology by Light), coordinated by Omar El Gawhary, submitted within the European Metrology Programme for Innovation and Research (EMPIR), call on Fundamental Metrology 2020, has ...

  • News - 01/11/2020

    Project GUSTO in the picture at TU Delft

    Jian-Rong Gao and his team are working very hard on project GUSTO. If all goes to plan, GUSTO (a helium balloon the size of a soccer stadium with a NASA telescope) will ...