IVM A undergoing End Item Testing
The first of two IVMs, which is designated IVM-A based on its location on the spacecraft (facing forward), started End Item Testing (EIT) this week. The EIT is a thorough functional checkout including calibration over temperature and serves as the entry point baseline for environmental testing. Environmental testing will include EMI/EMC, Vibration and Thermal Vacuum testing which simulate the launch and flight environments as closely as possible. Testing will be completed in about eight weeks.
While the IVM enjoys many years of heritage, the ICON IVM has improvements and modifications that will produce measurements of the plasma drift with unprecedented sensitivity to achieve the ICON science goals.
The second IVM (IVM-B) fabrication is following closely behind IVM-A and is in the final phases of test and assembly. IVM-B faces in the aft direction on the spacecraft during normal operations, when the remote sensing optical instruments view the northern hemisphere. However, it will be activated during operations when the spacecraft is rotated to allow the optical instruments to view the southern hemisphere.
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.
FUV instrument during testing
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.
FUV instrument testing door release mechanism
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.
The optical bench during integration and alignment at NRL, with the imaging optics installed, the interferometer in its housing on the left and the CCD detector on the right.
Completed optical assembly on the vibration table at NRL. It is carefully bagged to keep the hardware clean.
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. There’s a synopsis of the launch system on the SSL website as well.
It’s a great way to get to space, used successfully by many Explorers in the past.
On October 29th 2014, the ICON mission was reviewed at NASA Headquarters, where the project presented the status of the project, focusing on the work that had been done to design and formulate the mission to the Science Mission Directorate and the Deputy Administrator for Programs at NASA HQ. At this review ICON was successfully confirmed and was directed to proceed with formulation the mission.
The team has been working together through the successful Mission Preliminary Design Review in July and in the months that followed to reach this key milestones. Preparation for this step has also been a focus for colleagues in the Explorers Office at Goddard Space Flight Center and in the Heliophysics Division at HQ. Everyone involved is excited to proceed with the implementation of the mission!
The ICON Mission has now passed its Preliminary Design Review, where it is determined whether the design of the observatory and ground segment meet the mission requirements. After a season of 35 peer and design reviews that started back in April, the documentation and design for the Explorer were delivered and presented to the Standing Review Board at Orbital. Congratulations to the whole team are due, it has been an amazing effort! The impressive list of reviews undertaken between SRR and PDR is given below:
The ICON mission has passed its System Requirements Review, where the flowdown of top level requirements is traced through all aspects of mission implementation. We’ve gotten very good input from our Standing Review Board, whose key concerns become top priorities for the team to close out. Every NASA mission goes through this step on their way to the first design reviews, and we’re able to proceed with confidence that the team has a complete and verifiable set of requirements in hand. ICON has had a great systems engineering effort from the start and the mission, spacecraft and payload teams have been working together for years to get ready for this. Thanks to everyone who worked so hard on this review!
The ICON science team kicked off their effort in a meeting in November 2013. As the ICON instruments and spacecraft take shape, the science team will provide guidance, scientific oversight of the requirements and be developing the science data processing to enable ICON to deliver scientifically valuable products as quickly as possibly after launch. For more information on the team, go here.