The preliminary alignment for the Far Ultraviolet Spectrograph (FUV) instrument using visible wavelength light has been completed at Lockheed Martin. The next phase of testing will see the instrument ship to Belgium to complete the alignment in the FUV in a specialized vacuum chamber.

The FUV ICON instrument has an articulating field of view. In order to accommodate this, special machinery is required to rotate the instrument during alignment, testing and calibration while inside the vacuum chamber. Centre Spatial de Liege (CSL) in Belgium will provide this unique ultraviolet vacuum facility.

The design for the FUV instrument is such that the optical system can be focused using visible light and a visible grating, as well as FUV light and grating. This is preferable, since alignment using UV must be performed in a vacuum chamber, which makes it more challenging to conduct the alignment.

Over the past four weeks, the SSL team has been traveling to Lockheed Martin where the instruments’ mirrors were carefully adjusted to achieve best focus and optimum spectral performance at visible wavelengths. The visible wavelengths chosen were suitably scaled to simulate performance at the FUV operating wavelength.

The next phase of testing will see the optics package ship to Centre Spatial de Liege (CSL) in Belgium. After verifying the visible alignments were maintained, and no shifts happened during transport, the UV grating and the two UV cameras will be installed and UV alignment will begin.

ICON’s Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument includes two identical optical assemblies, one for each of the perpendicular fields of view that will observe thermospheric wind-vector and temperature profiles. An engineering unit of the optical assembly was completed and successfully vibration tested in June 2015 at the Naval Research Laboratory.

ICON's Extreme Ultraviolet (EUV) instrument is an “imaging spectrometer”. Its 2 dimensional detector records spectral information over the range 58.4 to 83.4 nm in the one direction, and records 12 degree wide x 1/4 degree high slices of the sky over a 16 degree field of view in the other direction.

In preparation for alignment of the toroidal grating used in the EUV instrument, an optical system has been setup to simulate the cylindrical wavefront. This simulates the instrument’s view for each slice of sky while in orbit. The optical set up consists of a convex sphere and a concave toroid that produces a line image on the EUV entrance slit to simulate what EUV will observe in space. This optics pair will be used to first align the EUV instrument using visible light, then the final alignment will take place in a vacuum chamber using EUV radiation, since EUV light is not transmitted in air.

During the review, each instrument and system were reviewed, and plans for integration of these systems onto a unified payload finalized. The team was successful in demonstrating their ability to complete these tasks on schedule. All instruments will be delivered to Utah for integration by the end of the calendar year, before delivery to Orbital ATK in Virginia by May 2016, in preparation for launch in June 2017.

Project Manager Bill Craig said “One of the key strengths was the consistency of the team; we were compared to the high quality expected of a Class B mission; a standard we set for ourself at PDR” and P.I. Thomas Immel complemented the team on an outstanding job in preparing and delivering a very successful review.

Congratulations to the entire ICON team… Onwards to Integration!

The Orbital Pegasus launch system was selected by NASA Launch Services to carry ICON into orbit. ICON will be launched over the Pacific Ocean after taking off from Kwajalein Atoll on the Orbital L-1011 that is part of the Pegasus launch system. Some pictures and discussion of the launch system can be found here. Here’s a synopsis of the launch system.

It’s a great way to get to space, used successfully by many Explorers in the past.