Ian Parry's Home Page
 

Active Research Projects
Exoplanets and Observational Techniques
 

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Chair of the Equality & Diversity Committee
University of Cambridge
Institute of Astronomy
Madingley Rd
Cambridge
CB3 0HA

 
Unfolding Space Telescopes for Astronomy and Earth Observations
I am the Principal Investigator (PI) for a research program to develop unfolding, self-aligning space telescopes.
    The power of space telescopes for astronomy has long been recognised.  The Earth's atmosphere blurs the images, blocks out many wavelengths and adds a bright background glow so space telescopes are much more powerful than ground-based telescopes . Yet in the mainstream wavelength range of 0.3 to 5.0 microns there has only been one general purpose space observatory (the Hubble Space Telescope) and a handful of specialised, smaller telescopes. Furthermore, in the next 15 years there will only be two general purpose successors to Hubble - the James Webb Space Telescope and WFIRST. A major reason for this is the cost of putting a large telescope in space. I am therefore working on techniques to reduce costs by making them small and light-weight in their launch configuration but large (and therefore powerful) once in orbit. This will make 2-4m class telescopes far more affordable and enable huge telescopes in the 10-30m class to be possible.

    In contrast, for Earth Observation (EO) there are already hundreds of telescopes in orbit looking down at the ground, although most of these are relatively small. For EO, unfolding telescopes offer significant cost reduction enabling affordable high definition imaging and on-demand imaging.

    The idea of unfolding space telescopes is not new and there are significant technical challenges. Firstly, we need an innovative and reliable unfolding scheme. Secondly, we need to put the deployed optics in to precise alignment and then continuously maintain that alignment. These require a very precise metrology system, a set of high accuracy actuators and a sophisticated control system.

    My research program started in 2017 and has so far received ~200k UKP in grant funding from STFC and UKSA. The main project stages are:

    • Lab prototypes to establish "proof of concept" for the deployment, metrology and control systems. This phase is almost complete.
    • Build and test a flight-ready unfolding CubeSat compatible space telescope. We're just starting this.
    • Launch and operate a CubeSat in-orbit technology demonstrator.
The pictures on the left show an 8U (20cm x 20cm x 20cm stowed) module for use as part of a 12U CubeSat. This unfolds to become a 0.9m telescope (upper image) which gives 30cm ground resolution for EO and 100 mas resolution for astronomy.

My collaborators in Cambridge are George Hawker (PhD student), Michael Johnson (visitor, PhD student at Imperial College), Richard Jakab (mechanical design engineer) and Karia Dibert (MASt student).

In July 2018 I was PI on a proposal summary to STFC in response to their call for Priority projects. The project was called "A 12U CubeSat (SUPERSHARP) for direct imaging of exoplanets"
 

Searching for Evidence of Extra-Terrestial Life (the 763nm Oxygen bio-signature)
SUPER-SHARP: Space-based Unfolding Primary for Exoplanet  Research via Spectroscopic High Angular Resolution Photography
SUPER-SHARP deployment sequence

This is the ultimate stage of the unfolding space telescope work described above - a telescope that can robustly search for extra-terrestial life. For details see the white paper, Parry et al 2018.

The pictures above show a concept for a 23.5m unfolding telescope that can fit into an Ariane 6 rocket. Each of the 4 mirrors in the cross-shaped primary is 10m x 2.8m.  SUPER-SHARP will directly image and obtain spectroscopy of exoplanets. Its instrumentation includes active mirror control, a coronograph (to remove the light from the central star for exoplanet observations) and an integral field spectrograph (to give R=100 spectra for every pixel in the 2x2 arcsec field of view). The 23.5m mirror baseline gives an inner working angle (IWA) of 16 mas at 750nm with 8 mas spatial resolution and an IWA of just 2.7 mas at ultra-violet wavelengths.

The SUPER-SHARP design philosophy is to push extremely hard on spatial resolution and IWA while at the same time keeping within an affordable budget. SUPER-SHARP will therefore maximise primary mirror baseline, use the shortest possible operating wavelength and be pragmatic about everything else (number of instruments, field of view, thermal management, raw speckle contrast, etc.). Some mirror deployment strategies (i.e unfolding mechanisms) can achieve even greater baselines than 23m.

The mission's main science goals are:
  • Carry out a "quick-look" reconnaissance of the ~500-1000 stars with the most readily observed habitable zones (HZ) making a census (including spectroscopy) of the number of Earths, Super-Earths, Neptunes and Jupiters in each system.
  • Do deep follow-up imaging and spectroscopy of those which actually have Earth-like planets in their HZ and look for the A-band 763nm oxygen bio-signature.
  • Thoroughly characterise all the other planets in the deep follow-up survey, chemically, physically and dynamically.
  • Directly image many exoplanets already discovered through the radial velocity technique (e.g the "hot Jupiter", Ups And b) or by GAIA. The hot-Jupiter science is enabled by the very small IWA.
 


    HR8799 P1640 S4 map
PROJECT 1640
    This was a near infrared integral-field spectrograph placed behind a high order AO system and a coronograph for direct imaging-spectroscopy of faint stellar companions including self-luminous extra-solar planets. P1640 was operational on the 5m Hale telescope at the Palomar Observatory. The top picture on the left shows our detection of all 4 of the known exoplanets orbiting the star HR8799. The second picture shows the P1640 spectra we obtained for these exoplanets. See Oppenheimer et al, 2013, Ap J, 768 for details. P1640 is a collaboration between the American Museum of Natural History, New York (PI: Rebecca Oppenheimer), Caltech, JPL and the IoA. Eleanor Bacchus was my PhD student at the IoA working on P1640.

    Our latest paper on the white dwarf companion to HD114174 can be found here

https://academic.oup.com/mnras/article/doi/10.1093/mnras/stx1171/3828085/Project-1640-Observations-of-the-White-Dwarf-HD

 


 
MOONS image
MOONS
    MOONS is a NIR fibre-fed multi-object spectrograph for the VLT. It will have 1024 fibres, a field of view of 25 arcmins diameter, spectral resolutions between R=4000 and R=20000 and a wavelength coverage of 0.8 to 1.8 microns. The project is currently well into the constuction phase. This project is led by the UKATC. My MOONS collaborators in Cambridge are Roberto Maiolino, Chris Haniff, David Buscher, Martin Fisher, David Sun and George Hawker. Science drivers for MOONS include galactic archaeology (especially the obscured bulge), Galaxy evolution at z>1, reionisation z>~7 and cosmology via RSD at z>1.

    We are currently assembling the 6 cameras in Cambridge.

    MOONS description paper.

    MOONS updated optical design paper.


 
E-ELT HIRES

This is the high resolution spectrograph for the European Extremely Large Telescope. Currently the project is in the conceptual design phase. There are numerous science drivers but the key ones are:
    • Exoplanet transit spectroscopy (including the possibility of detecting life)
    • Looking for the chemical signature of population-III stars
    • Cosmology and fundamental physics

My HIRES collaborators in Cambridge are Roberto Maiolino, Didier Queloz, Martin Haehnelt, Max Pettini, Chris Haniff, David Buscher, Martin Fisher and David Sun.

My student (George Hawker) and I recently published a paper on how HIRES can be used to detect the oxygen 763nm bio-signature for Proxima b and other exoplanets orbiting nearby M-dwarfs. See Hawker and Parry, 2019.


      
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           Last updated on June 20th 2019.