NASA’s Meteoroid Environments Office recently released two Technical Manuals (TMs): NASA Meteoroid Engineering Model Release 2.0 (TM-2015-218214) and Lunar Impact Flash Locations (TM-2015-218213).
“The release of these manuals is a prime example of the Meteoroid Environments team’s continued efforts to advance the understanding of the field and ensure the most up-to-date information on the meteoroid environment is made available to the agency’s programs and projects,” said Sue Aleman, Meteoroid Environments program executive.
MEM-R2
The Meteoroid Engineering Model Release 2.0 (MEM-R2) software is NASA’s most current and accurate model of the meteoroid environment, and the newly released manual is a support document for the updated software. It explains the software, how to run it and how to interpret the results.
“The focus is specifically on the model and not on the environment,” said Bill Cooke, Meteoroid Environments program manager at NASA’s Marshall Space Flight Center.
The software update was fairly basic: It includes a better graphic interface, bug fixes, and increased speed and efficiency. It came about as a result of needs for the now-canceled Constellation Program, but the added functionality for spacecraft and lunar orbit were still relevant for the Meteoroid Environments community.
One of the major benefits of the upgrade is that it was built to interface with BUMPER, NASA’s risk assessment code. Information from both MEM-R2 and Orbital Debris models can be put directly into BUMPER for analysis.
Any program or project with a spacecraft that will be in orbit will benefit from these increased capabilities.
“They need to evaluate the risk, so they need to know the model that characterizes that environment,” explained Cooke.
The International Space Station, for example, adopted MEM-R2 risk analyses as a requirement for all visiting vehicles, thereby affecting the Commercial Crew Program. Space Launch Systems has adopted a similar requirement, among other programs and projects.
Cooke doesn’t anticipate another MEM release for three or four years, as it will be a major update to the models.
Lunar Impact Flash Locations
The Lunar Impact Monitoring Program, part of the Meteoroids Environment Office, uses a combination of telescopes and video equipment to monitor lunar impacts by meteoroids. The Lunar Impact Flash Locations TM documents the locations of the impact-caused flashes spotted since the beginning of the program in 2006 — more than 350 impacts.
When meteoroids come towards the moon, there is no atmosphere to burn up the particles like there is on Earth, so they come in and directly strike the surface. The meteoroid is hitting the regolith at tens of thousands of miles per hour, which results in its vaporization and the release of lots of energy, a fraction of which is converted to the flash of light observed by the telescopes. If the meteoroid is large enough (bowling ball size), a crater with a diameter of several yards can be produced. These can be detected by high-resolution cameras onboard lunar orbiting spacecraft.
As a result, scientists are able to see an impact the size of a ping pong ball. Flashes are captured by the cameras, reviewed and used in a mapping software to document the locations, some of which may correspond to new craters. The findings are used to determine how similar meteoroids could affect spacecraft and bases on the moon, and can be applied to support spacecraft engineering and operations.
By communicating the location of these impacts in the TM, programs and projects (such as the Lunar Reconnaissance Orbiter) with orbiting spacecraft can image the actual craters. Because the crater can be observed directly and scientists know the energy of the impact from the flash, cratering models can be improved
“That was the real motivation of this TM so we could get these locations out so spacecraft could detect the craters left behind by these impacts,” said Cooke.
Both technical manuals are available through the NASA Technical Report Server.