Light at the end of Year
2014 has been a very eventful year. Developments on the design front notwithstanding, we also formulated a whole suite of tests to de-risk the systems we hope to fly to the Moon. Having got through the Definition and Assessment rounds of the Terrestrial Milestone Prizes (TMP), what remains is the Accomplishment round, in which each of the short-listed Google Lunar X Prize (GLXP) teams prove their mettle by demonstrating their designs in a show of strength and confidence on both hardware and software capability.
The Imaging TMP covers risk mitigation in the core elements of the Rover imaging system such as the camera optics and associated electronics as well as supporting systems that help achieve the team’s imaging objectives. We will be putting the imaging system through its paces with functional and performance tests to establish its capabilities and match them with the minimum requirements demanded by the mission. Once we have benchmarked the camera through a scene simulation, which involves imaging an optical mockup of the lunar terrain, we have a quantitative estimate of its performance that now has to be matched during the environmental tests.
Creating the lunar mockup was a rewarding experience – in part due to the sheer visual treat the final result gives to the human eye. A desolate landscape recreated to scale with the characteristic craters, mounds and faraway highlands in miniature was just the place to take our Rover out for a spin. The optical effect is complete once the mockup is assembled within a light-proof Sun-simulator chamber. Still images and high-definition videos captured during this ‘Scene Simulation’ would give us a sample set of data products we can expect from the current imaging system design and help identify areas for improvement. A key outcome of this test is the verification of the camera’s dynamic range (ability to pick up both the brightest and darkest regions in a scene), white-balance and saturation characteristics in the ambient reflective lunar albedo.
The camera is first put through a vibration test to check if it can survive the ride into orbit on the PSLV rocket without sustaining even the slightest damage. The imaging module thus qualified, will be placed in a thermal vacuum (T -Vac) chamber that simulates the environment on the surface of the Moon both at the highest (+120 °C) and the lowest (-150 °C) typical temperatures. The performance of the camera itself will be checked against the results of the benchmarking tests completed earlier. Due to the stringent demands of space, even a partial failure leads to a recommendation demanding a repetition of the test after incorporating modifications. Despite the effort put in, we will still have our fingers crossed as the hardware undergoes testing and relax only once the results vindicate our design.
An end-to-end demonstration of how we would execute a Mooncast (live transmission from the Moon) takes the cake in terms of challenging the whole team. This activity, termed a Ground Mooncast Demonstration, helps rehearse for an actual scenario during lunar surface operations which forms the trickiest phase of the mission. Remotely controlling the Rover, while dynamically identifying points of interest, articulating the Camera mast, capturing the scene in high-definition and then relaying it to Mission Control takes a lot of planning. A number of engineering groups make this possible – from the C&DH group interfacing the Camera with the Communication modules, to the Electrical group provisioning for power-intensive Rove-and-Shoot operations, not forgetting the Camera and software development group which is working round-the-clock to keep the data size low while maintaining the highest image quality.
With this year’s late winter round the corner, we hope that Shelley’s Spring shall follow; with us having matched if not exceeded the prowess so far associated with government agencies alone. Per aspera, ad astra!