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Because the season has turned to winter in Jezero Crater, circumstances have turn out to be more and more difficult for Ingenuity, which was designed for a brief flight-test marketing campaign throughout the a lot hotter Martian spring. Elevated quantities of mud within the ambiance, mixed with decrease daytime temperatures and shorter days, have impacted Ingenuity’s power finances to the purpose the place it’s unable to maintain itself heat all through the Martian nights. In its new winter operations paradigm, Ingenuity is successfully shutting down throughout the evening, letting its inner temperature drop to about minus 112 levels Fahrenheit (minus 80 levels Celsius) and letting the onboard electronics reset. This new manner of working carries with it dangers to Ingenuity’s digital elements, lots of which aren’t designed to outlive the temperatures they’re being uncovered to at evening. Furthermore, excessive temperature cycles between daytime and nighttime are inclined to trigger stresses that may end up in element failure.
Over the previous a number of sols on Mars, the Ingenuity workforce has been busy recommissioning the helicopter for flight, going via a sequence of actions that embody preflight checkout of sensors and actuators and a high-speed spin of the rotor. These actions have revealed that one of many helicopter’s navigation sensors, known as the inclinometer, has stopped functioning. A nonworking navigation sensor feels like an enormous deal – and it’s – nevertheless it’s not essentially an finish to our flying at Mars.
Navigation Sensors
When Ingenuity is flying, the onboard flight management system retains shut monitor of the helicopter’s present place, velocity, and orientation. It does so with the assistance a sensor suite consisting of:
- an inertial measurement unit (IMU), which measures accelerations and angular charges in three instructions
- a laser rangefinder, which measures the gap to the bottom
- a navigation digicam, which takes footage of the bottom under
The info from these sensors is processed by a set of algorithms applied on Ingenuity’s navigation laptop. For the algorithms to perform correctly, they should be initialized previous to takeoff with an estimate of Ingenuity’s roll and pitch angle. That is the place the inclinometer is available in.
The inclinometer consists of two accelerometers, whose sole function is to measure gravity previous to spin-up and takeoff; the path of the sensed gravity is used to find out how Ingenuity is oriented relative to the downward path. The inclinometer will not be used throughout the flight itself, however with out it we’re compelled to discover a new strategy to initialize the navigation algorithms previous to takeoff.
Impersonating the Inclinometer
Ingenuity’s sensor suite gives some redundancy in the case of sensing angle on the bottom. The IMU comprises accelerometers, which – similar to the accelerometers throughout the inclinometer – can be utilized to estimate the preliminary angle. In contrast to the inclinometer, the IMU will not be purpose-built for sensing static orientation, so its preliminary angle estimates will typically be considerably much less correct. Nonetheless, we consider an IMU-based preliminary angle estimate will enable us to take off safely and thus gives a suitable fallback that may enable Ingenuity to renew flying.
Making the most of this redundancy requires a patch to Ingenuity’s flight software program. The patch inserts a small code snippet into the software program working on Ingenuity’s flight laptop, intercepting incoming rubbish packets from the inclinometer and injecting substitute packets constructed from IMU knowledge. To the navigation algorithms, all the pieces will look as earlier than, the one distinction being that the acquired inclinometer packets don’t really originate from the inclinometer.
Anticipating that this example may probably come up, we ready the required software program patch previous to final yr’s arrival on Mars and stored it on the shelf for this eventuality. We’re due to this fact capable of transfer rapidly with the replace, and the method of uplinking it to Ingenuity is already underway.
Returning to Service
If all goes properly, over the following few sols, the workforce expects to finalize uplinking and making use of the software program patch, which shall be adopted by commissioning actions to make sure the brand new software program is working as deliberate. Barring further surprises, we anticipate that Ingenuity will take to the skies for Flight 29 – a repositioning transfer to the southwest designed to maintain us inside communication vary of Perseverance – within the close to future.
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