Direct from Mars: Perseverance lenses enhance surface images

The first high-res color image from the Mars surface, provided from Perseverance using a lens assembly from Jenoptik. (NASA/JPL-Caltech)

Hundreds of companies and research groups have taken part in developing the Perseverance rover now on Mars, along with the Ingenuity Mars Helicopter attached underneath.   When the rover descended and landed on Feb. 18, it began sending thousands of images, many in high resolution color.  

Jenoptik developed cutting edge lenses used aboard the rover to create many of those images, not only for public consumption but to help the rover navigate, avoid hazards and collect Martian soil samples for eventual return to Earth. Fierce Electronics spoke to Jenoptik North America President Jay Kumler about the steps involved in working with NASA/JPL.  

FE: Jenoptik has worked with NASA and JPL on space projects before, going back to Hubble, I believe, but can you share a little how the work on Perseverance first began?

Kumler: The relationship with key JPL optical engineers goes back to 1993 when we first built a space qualified instrument for members of the EECAM (Enhanced Engineering Cameras) team.  The initial request for quotation for Perseverance came from NASA/JPL in 2015.  JPL solicited several companies to design and build the EECam’s in a competitive bid.

FE: What is Jenoptik’s purpose and priority on working on space projects? For example, is this a good way for your company to showcase your work, or is it more of a chance to fine-tune R&D work? And Is it profitable at all, or an investment?  

Kumler: Over the years, we have built space qualified hardware for a number of NASA programs, but we have been more selective in recent years.  It is a great way to challenge our R&D team, to expand our in-house technology, and an effective way to demonstrate our world-class capabilities.  We definitely made investments on our side to ensure the mission success.

FE: Your company is diversified into public security, smart cities, many areas, but could the space segment become more important in the future?

Kumler: We are participating in select space programs now and have indicated to JPL that we would supply these same lenses again if they were used on a future program.  The space segment will remain a small but important part of our overall global business.

FE: Can you describe the way you work with NASA with testing and collaboration? Is this very manpower intensive?

Kumler: We work in an open and collaborative manner with NASA engineers.  This is necessary when designing part of a camera system -- all parts obviously need to work together, and the camera lenses must be delivered in a timely manner.    

The design effort requires a team of experienced Jenoptik engineers to develop the camera lens designs, tolerance the system, model the system over wide operating conditions and detail all the parts of the camera lens assemblies.  The engineering effort to design and build the test equipment that will validate the lenses was also extensive.  The tooling alone for aligning, bonding and testing the EECAM lens assemblies required 200 drawings.

FE: The cameras aboard Perseverance are working well. What makes them special?  I learned the Navcams can distinguish an object as small as a golf ball at a distance of 80 feet, for example.

Kumler:  The reference to distinguishing a golf ball at 82 feet comes from NASA.  It’s not a technical specification –-it is just an illustration to give the public an impression on how well the NavCam cameras work.  The illustration only applies to the Navigational cameras.

The technical specifications for the EECAM lens assemblies are quite detailed.  For the NavCam, there are 16 individual parameters that need to be measured and reported, including polychromatic MTF, transmission, relative illumination and lateral color over the full operating conditions of the cameras.  

A definitive technical reference describes the enhanced engineering cameras. This paper also covers the Entry Descent Landing (EDL) lenses and gives an excellent reference for all technical specifications which are made public.

FE: The video that NASA shared of the EDL was shot with COTS gear, according to NASA.  That sounds like it was added at a smaller budget and later in the process.  Can you comment on the value of more expensive and more industrial grade camera mechanisms and lenses such as ones from Jenoptik? Would you have wanted to provide the cameras used during EDL, for example?  

Kumler: Jenoptik did not bid on the EDL cameras and was not involved in the development. The Maki paper indicates: “The EDLCAMs were developed with a minimal number of key requirements. The first requirement was that the EDLCAMs must not interfere with the flight system during the critical EDL phase of the mission. This requires that the EDLCAM imaging system have zero or near zero interaction with the MSL-heritage flight system elements during EDL.

“The EDL camera system was categorized as a technology demonstration during development, and the system uses a significant amount of commercially available hardware, qualified and modified for EDL use.”

We did not have COTS cameras that met the requirements for the EDL cameras, which were ultimately supplied by Point Grey, a business unit of FLIR, so there was not a fit.

The value of the custom lenses is to maximize performance on mission-critical portions of the rover.  This allows the engineers to achieve exactly the field of view, resolution and optical performance they want for optimum operation of the rover on the surface.

There is an excellent summary of the reasons to design custom lenses for the NavCam and HazCam in paragraph 2.1.2 in the paper.

FE: NASA is always seeking ways to lower prices. They even used some of the spare parts from Curiosity. Is there always pressure to lower costs?

Kumler: There is usually pressure to control costs without taking any shortcuts on reliability or performance.  Price was one part of the selection criteria when NASA selected Jenoptik to develop the camera lenses.

FE: Can you say what a single lens like those you are providing on Perseverance has cost or would cost on the open market? Or a range?

 Kumler: We would rather not comment on the cost of individual lenses because it is competition sensitive.  The lenses are considerably more expensive than commercial off the shelf (COTS) lenses because they are fabricated in extremely small quantities, they operate over extreme environmental ranges, and they are delivered with a mountain of test data for each lens.  There is no room for error.  Everything must be documented.  

 FE: What can you tell us about how the lenses are made?

 Kumler: Each camera lens assembly supplied by Jenoptik is a complex assembly of metal and glass parts.  The optical elements needed to be aligned to each other to within micron-level tolerances.  The surface finishes of these parts are just as critical as the dimensional tolerances.

In order to meet the EECAM requirements, Jenoptik had to develop and refine several unique test capabilities.  We tested the lens assembly performance over a wide temperature range, including extremely cold Martian temperatures.  We were also able to build the lenses in extremely demanding clean room conditions. 

Interplanetary contaminations from the CacheCam lens assembly were a significant concern of NASA – the samples from Mars need to be uncontaminated by any microscopic particles from Earth.  We learned a lot in the process of learning how to operate the lenses at extremely cold temperatures, and our lenses are the cleanest we have ever built.

FE:  Your lens assemblies are used in three main areas, but how many actual cameras does that total?

Kumler: There are 3 types of cameras designed for surface operations:  Navigation cameras or Navcams, quantity 2; Hazard Avoidance Cameras or Hazcams, quantity 6; and the Cachecam, quantity 1. 

The Navcams acquire color stereo images of the surface with a 96 degree × 73 degree field of view at 0.33 mrad/pixel. The Hazcams will acquire color stereo images of the surface with a 136 degree × 102 degree field of view at 0.46 mrad/pixel. The Cachecam, a new camera type, will acquire images of Martian material inside the sample tubes during caching operations at a spatial scale of 12.5 microns/pixel.

navcamimagefromperseverance
Perseverance NAVCAM high-res image (NASA/JPL-Caltech)

Editor’s Note: NASA  posts raw images from Mars online with hundreds posted nearly every day.

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