Mr. Aman Chandra Profile

Aman Chandra

at Univ of Arizona

SPIE Involvement:

Author

Publications (6)

Proceedings Article | 27 August 2022 Presentation + Paper

Orbiting astronomical satellite for investigating stellar systems (OASIS): a paradigm shift in realizing large space telescopes

Siddhartha Sirsi, Christopher Walker, Jonathan Arenberg, Yuzuru Takashima, Daewook Kim, Heejoo Choi, Arthur Palisoc, Henry Quach, Marcos Esparza, Kevin Derby, Luke Mayer, Tianyao Zhang, Aman Chandra, Anthony Stark

Proceedings Volume 12180, 121801Q (2022) https://doi.org/10.1117/12.2629100

KEYWORDS: Space telescopes, Receivers, Astronomy, Optical design, Satellites, Mirrors, Cryogenics, Space operations, Metrology, LIDAR

Read Abstract +

Proceedings Article | 24 August 2021 Open Access

Deflectometry-based thermal vacuum testing for a pneumatic terahertz antenna

Henry Quach, Marcos Esparza, Hyukmo Kang, Aman Chandra, Heejoo Choi, Joel Berkson, Karlene Karrfalt, Siddhartha Sirsi, Yuzuru Takashima, Art Palisoc, Jonathan Arenberg, Kristy Gogick Marshall, Christopher Glynn, Sean Godinez, Marcos Tafoya, Christopher Walker, Christian Drouet d'Aubigny, Daewook Kim

Proceedings Volume 11820, 118200W (2021) https://doi.org/10.1117/12.2594902

KEYWORDS: Deflectometry, Calibration, Cameras, Antennas, Metrology

Read Abstract +

DOWNLOAD PAPER

Proceedings Article | 24 August 2021 Open Access

Analytical and finite element analysis tool for nonlinear membrane antenna modeling for astronomical applications

Arthur Palisoc, Gerard Pardoen, Yuzuru Takashima, Aman Chandra, Siddharta Sirsi, Heejoo Choi, Daewook Kim, Henry Quach, Jonathan Arenberg, Christopher Walker

Proceedings Volume 11820, 118200U (2021) https://doi.org/10.1117/12.2594050

KEYWORDS: Reflectors, Finite element methods, James Webb Space Telescope, Telescopes, Mirrors, Antennas, Inverse problems

Read Abstract +

The uninflated shape configurations of parabolic and spherical membrane mirrors were calculated by solving the inverse problem, i.e., given the design inflation pressure, the membrane material and geometric properties, what must be the initial uninflated shape such that on inflation to the design pressure, the exact desired surface of revolution is obtained. The resulting first order nonlinear differential equation was numerically integrated using the boundary conditions. The initial uninflated shape was then subjected to a forward transformation using FAIM, a proprietary geometric nonlinear membrane finite element code. FAIM has been validated against exact analytical solutions for both small and extremely large deformations that are up to eight orders of magnitude larger compared with the starting undeflected shape. Simulations reveal that to fabricate a very accurate and precise inflated membrane mirror relative to the design parameters, one must not only accurately measure and input the moduli in both meridional and hoop directions but an accurately measured Poisson’s ratio as well. The code was used to guide the membrane mirror design. For very small aperture diameters, the initial uninflated shape may be fabricated by thermo-forming the membrane. For aperture diameters exceeding one meter however, the membrane mirror is built with discrete gores that are joined together with tapes at the seams. This provided the impetus to write a companion computer code FLATE, to calculate the gore shapes using a slight modification of the solution to the inverse transformation equation to account for the presence of the seam tapes. After the gores were determined, the resulting final inflated shape was calculated and verified using FAIM. Sensitivity analyses can now be carried out to determine the resulting surface shape as a function of the different sources of error: gore width, gore length, perimeter attachment uncertainties, thermal effects, variation of material properties over the membrane continuum and inflation pressure changes. The code has been shown to be more robust than equivalent commercial analytical packages in so far as membrane, cable and space-frame element combinations are concerned. In particular, the analytical and finite element codes were used in the preliminary assessment of a membrane optic for the OASIS Mission (Orbiting Astronomical Satellite for Investigating Stellar Systems) [1]. The OASIS is a 20-meter class space observatory operating at high spectral resolution in the terahertz frequencies. Over its nominal 2-year mission it will probe conditions and search for biogenic molecules on hundreds of protoplanetary disks and other solar system objects.

DOWNLOAD PAPER

Proceedings Article | 24 August 2021 Presentation + Paper

OASIS architecture: key features

Jonathan Arenberg, Michaela Villareal, Jud Yamane, Tony Yu, Justin Lazear, John Pohner, Mitchell Sangalis, Steven Jackson, Elisabeth Morse, Ryan Tyler, Pradipto Ghosh, Art Palisoc, Christopher Walker, Yuzuru Takashima, Daewook Kim, Siddhartha Sirsi, Aman Chandra

Proceedings Volume 11820, 118200S (2021) https://doi.org/10.1117/12.2594681

KEYWORDS: Observatories, Reflectors, Receivers, Space operations, Telescopes, Sun, Solar radiation models, Solar radiation, Mirrors, Bolometers

Read Abstract +

Proceedings Article | 24 August 2021 Open Access

Stressed deformable reflector design and pneumatic membrane antenna for cryogenic thermal vacuum chamber testing

Marcos Esparza, Heejoo Choi, Hyukmo Kang, Christian d'Aubigny, Amarjiit Pandde, Henry Quach, Aman Chandra, Karlene Karrfalt, Yuzuru Takashima, Art Palisoc, Jonathan Arenberg, Kristy Gogick Marshall, Christopher Glynn, Sean Godinez, Marcos Tafoya, Brandon Chalifoux, Christopher Walker, Daewook Kim

Proceedings Volume 11820, 118200R (2021) https://doi.org/10.1117/12.2594403

KEYWORDS: Actuators, Reflectors, Computer aided design, Antennas, Prototyping, Polonium, Reflector design, Aluminum, Wavefronts, Solid modeling

Read Abstract +

DOWNLOAD PAPER