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The New Shepard (NS) Booster, NS-11 will land after the vehicle’s fifth flight during May 2, 2019. Credit: Blue Origin
Some of the most interesting places to study in our solar system are found in the most hospitable atmosphere – but landing on any planetary body is already a dangerous proposition. With NASA Planning new locations on the moon and robotic and crew missions MarsAvoiding landing on a steep slope or in a boulder area is important to ensure safe exposure to other world surfaces. To improve landing safety, NASA is developing and testing a suite of specific landing and hazard-avoidance techniques.
The combination of laser sensor, camera marrow, high-speed computer and sophisticated algorithms will give the spacecraft artificial eyes and analytical capabilities that will be given to detect designated landing areas, identify potential hazards and adjust course at a safe touchdown site. Technologies developed under the Space Technological Mission G Mission Directorate’s Game Changing Development Program – Safe and Precise Landing – Integrated Capabilities Evolution (SPLIS) project, will increase the size of stones, craters and landings for spacecraft. The football field is already targeted as relatively safe.
A new suite of lunar landing techniques, called Safe and Accurate Landing – Integrated Capabilities Evolution (SPLIS), will enable safer and more accurate lunar landings than ever before. Future lunar missions could use NASA’s advanced splicing algorithms and sensors to target landing sites that were not possible during the Apollo mission, such as hazardous rocks and regions with nearby shadow craters. Splice techniques can also help humans land on Mars. Credit: NASA
Three of Spice’s four main subsystems will have their first integrated test flight on the Blue Origin New Shepard rocket during the next mission. As the rocket’s booster returns to the ground, after reaching the boundary between the Earth’s atmosphere and space, the splash’s terrain-related navigator, navigation doppler leader, and native and landing computer will run on the booster. It will work the same way when each moon comes close to the surface.
The fourth major splice component, risk detection leader, will be tested by future ground and flight tests.
Follows in breadcrumbs
When a site is selected for research, part of the consideration is to ensure adequate space for the spacecraft landing. The size of this area, called the landing ellipse, reflects the precarious nature of legacy landing technology. The target area for Apollo 11 in 1968 was about 11 miles 3 miles, and the astronauts operated the lander. Subsequent robotic missions were created for autonomous landings on Mars. The Vikings arrived on the Red Planet after 10 years with a target ellipse of 174 miles by 62 miles.
The Apollo 11 landing ellipse shown here was 11 miles 3 miles. Precision landing technique will sharply reduce the landing area, allowing for multiple mission landings in the same area. Credit: NASA
Technol improved G, and subsequently reduced the size of the autonomous landing zone. In 2012, the Curiosity Rover landing ellipse was 12 miles below 4 miles.
Being able to direct the landing site will help future missions target areas targeted for new scientific research previously considered too risky for non-pilot landings. It will also enable advanced supply missions to send cargo and supplies in one place instead of spreading miles away.
Each planetary body has its own specific conditions. “Spices are designed to coordinate with any spacecraft landing on any planet or moon,” said project manager Ron Sostaric. Based on NASA’s Johnson Space Center in Houston, Sostaric explained that the project agency extends to several centers.
Terrain-related navigation provides navigation measurements by comparing real-time images with known maps of surface features during descent. Credit: NASA
“What we are building is a complete descent and landing system that will work for future Artemis missions to the moon and could be adapted for Mars,” he said. “Our job is to put the individual components together and make sure they work as a functioning system.”
Atmospheric conditions may vary, but the process of descent and landing is the same. The SPLICE computer is programmed to enable terrain-related navigation a few miles above the ground. The board nabord camera takes photographs on the surface, taking up to 10 pictures per second. It is constantly fed into a computer, preloaded with a database of landing area satellite images and known landmarks.
Algorithms look for real-time images for known features to determine the spacecraft’s location and safely navigate the craft to its expected landing point. It’s like navigating through building-like landmarks, rather than street names.
Similarly, a terrain-related research spacecraft identifies where it is and sends that information to a guidance and control computer, which is responsible for operating the flight path on the surface. The computer spacecraft will almost certainly know what it should be near its target, almost laying in breadcrumbs and then following them to the final destination.
This process continues for about four miles from the surface.
Laser navigation
It is necessary to know the exact position of the spacecraft for the calculations required for planning and executing the power descent for a specific landing. In the middle of the descent, the computer turns on the navigation Doppler leader to advance velocity and range measurements that add in specific navigation information coming from a terrain-related navigation. The leader (light detection and ranging) works just like radar but uses light waves instead of radio waves. Three laser beams, each as narrow as a pencil, are drawn towards the ground. Light from this beam bounces off the surface, reflecting it towards the spacecraft.
NASA’s research Doppler leader instrument consists of a chassis with electro-optic and electronic components, and an optical head with three telescopes. Credit: NASA
The travel time and wavelength of that reflected light are used to calculate how far the craft is from the ground, in which direction and how fast it is moving. These calculations are made 20 seconds per second for all three laser beams and feed into the guide computer.
The Doppler leader works successfully on Earth. However, Farzin Amzajardian, co-inventor and chief investigator at NASA’s Langley Research Center in Hampton, Virginia, is responsible for tackling the challenges of space use.
He said it was still unknown how many signals would come from the surface of the moon and Mars. If the ground material is not very reflective, the signal given back to the sensor will weaken. But Amzazardian is confident that the leader will advance radar technology, as laser frequency is an order of magnitude higher than radio waves, enabling better accuracy and more efficient sensing.
Langley engineer John Savage inspects the section of the navigation Doppler leader unit after its construction from a block of metal. Credit: NASA / David C. Bowman
The desktop and landing computer is responsible for managing all this data. Navigation data from sensor systems are fed to onboard algorithms, which calculate the new route for a particular landing.
Computer powerhouse
The descent and landing computer synchronizes the functions and data management of individual spice components. It should also be integrated with other systems on any spacecraft. Therefore, this small computing powerhouse keeps precision landing techniques from overloading the primary flight computer.
The calculation requirements initially identified made it clear that existing computers were inadequate. NASA’s high-performance spaceflight computing processor will meet demand but is still many years away from completion. Spilis needed an interim compromise to prepare for the first suburban rocket flight test with Blue Origin on its new Shepard rocket. Data from the performance of the new computer will help shape its final replacement.
The spare hardware vacuum chamber is undergoing preparation for testing. Three of Splice’s four main subsystems will have their first integrated test flight on the Blue Origin New Shepard rocket. Credit: NASA
John Carrs, technical integration manager for precision landings, explained that “the surrogate computer has a very similar processing technology, signaling both future high-speed computer design, as well as future native and landing computer integration efforts.”
Looking ahead, test missions like this will help build a safe landing system for missions by NASA and commercial providers on the lunar surface.
“There are still many challenges to landing safely and precisely on another world,” Carson said. “There is no commercial technology yet that you can go out and buy this. Every future surface mission can use this precision landing capability, hence the NASA meeting that is needed now. And we’re relocating and using it with our industry partners. “
