This illustration portrays Mars Helicopter Ingenuity during a test flight on Mars. Resourcefulness was taken to the Red Planet strapped to the tummy of the Perseverance rover (seen in the background). Ingenuity, an innovation experiment, was the very first aircraft to try controlled flight on another world in 2021. Credit: NASA/JPL-Caltech
In the months considering that we flew for the first time, we have discovered a great offer about running a helicopter on Mars. We have actually checked out Ingenuitys strengths and limitations in information, leveraging the former and working around the latter to operationalize it as a highly capable reconnaissance platform.
With the advantage of the knowledge gotten, carrying out flights on Mars has in the majority of ways become much easier than it was at the start. In one crucial way it is really getting more difficult every day: Im talking about the atmospheric density, which was already very low and is now dropping further due to seasonal variations on Mars.
When we checked and designed Ingenuity on Earth, we expected Ingenuitys five-flight objective to be finished within the first couple of months after Perseverances landing in February 2021. With Ingenuity in its sixth month of operation, however, we have actually gone into a season where the densities in Jezero Crater are dropping to even lower levels.
Resourcefulness, a technology experiment, was the first airplane to try regulated flight on another planet in 2021. When we evaluated and designed Ingenuity on Earth, we expected Ingenuitys five-flight objective to be completed within the very first few months after Perseverances landing in February 2021. For Ingenuitys rotor we do not anticipate to experience this phenomenon till even greater Mach numbers, however this has never ever been validated in testing on Earth.
Additional demands will likewise be put on several components of Ingenuitys style: The motors will need to spin faster, the electrical system will need to deliver more power, and the entire rotor system will require to endure the higher loads that come with increased rotor speeds. It all adds up to a considerable obstacle, however by approaching the issue gradually and systematically, we hope to completely examine out the system at greater rotor speeds and enable Ingenuity to keep flying in the months ahead.
Mars Helicopter Sol 193– Navigation Camera: NASAs Ingenuity Mars Helicopter obtained this image using its navigation cam throughout its 13th flight on Sep. 5, 2021 (Sol 193 of the Perseverance rover objective) at the regional mean solar time of 12:06:30. Credits: NASA/JPL-Caltech
At our lower design limitation for climatic density (0.0145 kg/m3), we know that Ingenuity has a thrust margin of at least 30%. If the climatic density were to drop to 0.012 kg/m3 in the coming months, our helicopters thrust margin might drop to as low as 8%, which implies that Ingenuity would be running close to aerodynamic stall (a condition where additional increases in the blades angle of attack does not produce more lift, just more drag).
Luckily, there is a method to tackle this issue– however it involves spinning the rotors even much faster than we have actually been doing up to now. They will have to spin faster than we have actually ever tried with Ingenuity or any of our test helicopters on Earth. This is not something we ignore, which is why our next operations on Mars will be focused on carefully checking out higher rotor speeds in preparation for future flights.
We will start by performing a high-speed spin of the rotor without leaving the ground, reaching a peak rotor speed of 2,800 rpm (more than a 10% increase relative to our prior Mars experience of 2,537 rpm). We will follow this with a brief test flight at a slightly lower rotor speed of 2,700 rpm if all goes well. This would be our 14th flight and (ideally) a reasonably boring one compared to any of our more recent flights, where we flew long distances to get pictures of interest for the Perseverance rover group. Happening no earlier than Friday, Sept. 17 (with data boiling down no earlier than Saturday early morning), the brief hop would have Ingenuity remove, climb to 16 feet (5 meters), perform a little translation (sideways relocation), and then land once again. And while the outcomes from a Flight 14 should be less than captivating, the significant boost in offered rpms (from 2,537 to 2,700) for future helicopter operations will provide us the choice to carry out hunting objectives for Perseverance at lower climatic densities. It likewise leaves some wiggle space if we decide an extra rpm boost is required later.
If the blade suggestions get sufficiently close to the speed of sound, they will experience a very large boost in aerodynamic drag that would be prohibitive for flight. For Ingenuitys rotor we do not expect to experience this phenomenon up until even greater Mach numbers, but this has never ever been verified in screening on Earth.
Another possible problem is unknown resonances in the helicopter structure. Like all mechanical systems, Ingenuity has resonances that can result in big vibrations when thrilled at particular frequencies. It is important to make sure that there are no substantial resonances at the rotor speed used for flight, as this could cause damage to hardware and cause a degeneration in sensor readings needed by the flight control system.
Extra needs will also be placed on several elements of Ingenuitys design: The motors will need to spin faster, the electrical system will need to provide more power, and the whole rotor system will need to stand up to the higher loads that come with increased rotor speeds. It all amounts to a considerable obstacle, however by approaching the issue slowly and methodically, we intend to totally have a look at the system at greater rotor speeds and make it possible for Ingenuity to keep flying in the months ahead. Stay tuned for updates.
Written by Håvard Grip, Ingenuity Mars Helicopter Chief Pilot at NASAs Jet Propulsion Laboratory.