R&D Triumphs in Asteroid Exploration

Asteroids are becoming increasingly interesting in space research. Not quite big enough to qualify as a planet but not small enough to be ignored, these celestial bodies were once thought of as a nuisance for leaving trails across photographs, ruining them for deep sky studies.

Now we know that what was once considered just a grey lump of rock could in fact be used to track the dynamic events that shape our solar system, might have brought life to Earth billions of years ago and may even be a future source of valuable elements and water.

This weekend marks Asteroid Day, which raises awareness of these fascinating objects and marks the 1908 Tunguska airbust above Siberia – the largest observed asteroid strike in recorded history.

When an asteroid or comet passes within 1.3 astronomical units of the Sun (just outside of Earth’s orbit) it becomes known as a Near Earth Object (NEO). As of June 2024, the Minor Planet Centre has recorded more than 35 thousand NEOs, almost 100 this month alone.

The threat that these primordial remnants of our early Solar System might one day impact the planet offers a compelling reason to track them closely. While the probability of a large impact is low, if one occurs it could create a humanitarian crisis and potentially be considered an extinction event.

The possibility for catastrophe makes it vital to invest resources in mitigating the risks NEOs pose. ESA plays a vital role in monitoring and studying asteroids, especially with its Space Safety Programme, and its wider R&D efforts now are essential if future missions want to better understand asteroid mining or test planetary defence methods. From creating radiation-hardened components that could withstand long arduous space flights, to investigating the materials and systems needed for resource mining, ESA’s Technology Programmes have a long history of developing the technologies future asteroid missions might need.

To mark Asteroid Day we look below at several of these R&D activities, LUMIO, HERA, and PANGU and how they exemplify ESAs efforts to drive forward our understanding of these intriguing entities.

LUMIO: A shining light for meteoroid impacts

Just this week ESA’s Council have approved the next stage of the Lunar Meteoroid Impacts Observer (LUMIO) [LINK to LUMIO article], a future CubeSat mission to study the number of impacts on the far side of the Moon.

While many surveys detect NEOs as small as 1metre in size, there are few methods for watching the smaller meteoroid population. Funded through GSTP Element 3, LUMIO will observe and measure micro-meteoroid impacts on the lunar surface furthest from Earth, to better understand how these impacts occur, how often and what damage they can cause.

There are several ways to know when an impact has occurred, whether that’s seeing the seismic wave create by the impact or a visible crater it leaves on the surface. By studying the light flashes produced as these micro meteoroids crash into the lunar surface, LUMIO will collect data to complement the Earth-based surveys and observations of these impacts in the hope of significantly improving current meteoroid models and making a fundamental contribution to ESA’s space safety awareness and monitoring efforts.

Knowing more about these impacts will mean we can map more NEOs in the Solar System and will help answer questions such as: when could the next large meteoroid impact Earth? What threat do these meteoroids pose to a future lunar colony? How quickly can micro meteoroids degrade space equipment?

Are Near Earth Objects allies or adversaries?

Missions like ESA’s HERA, which is due to launch in October, will provide critical information by observing how an asteroid moves following an impact, specifically Dimorphos, the orbiting moonlet of the Didymos binary asteroid system. The mission is part of the ESA/NASA collaboration to test asteroid deflection techniques as part of wider plans to implement planetary defence tactics.

The early phases of the mission and the development of its CubeSats was initially funded through GSTP.

The probe and its two CubeSats, Juventas and Milani, will survey the impact crater previously left by NASA’s DART mission, ultimately helping scientists understand the impact dynamics and the resulting changes in the asteroid's trajectory. This knowledge is key to developing potential asteroid deflection strategies, a vital aspect of planetary defence.

Hera will prove several new technologies such as visual-based asteroid close-proximity navigation and control, inter-satellite communication and a novel even more precise delta-DOR interplanetary radio-tracking and navigation technique – all of which pave the way for future interplanetary missions.

Among the many innovative, technology demonstration aspects of this mission, the use of CubeSats in deep space marks a significant leap forward in space technology. As part of the development of the mission, GSTP has also funded the development of a CubeSat deployer suitable for deep space missions. 

A similar GSTP-funded mission to study an asteroid, the Miniaturised Asteroid Remote Geophysical Observers (M-Argo) spacecraft will rendezvous with an asteroid to characterise its shape, the mass and to see what the surface is made up of, for example minerals  that might be useful as future resources.

Ready for your close up: Simulating models for success

As meteoroids come from asteroids and comets, the models used to understand asteroids are also helpful in predicting their paths through the Earth and Moon orbit and to see whether or not they pose a hazard.

The Planet and Asteroid Natural Scene Generation Utility (PANGU) software generates realistic images of planets and asteroids, on a real-time basis, to simulate asteroid surfaces so that landing algorithms or precise orbits can be calculated.

The tool creates hyper realistic images of asteroids and planets which can be used to trial different scenarios that a mission might meet.  The software is being used for Hera, which will orbit with a precise trajectory compared to Dimorphos. To prepare the mission’s navigation algorithm, lots of different images are being generated using different models and different illumination conditions so that once Hera arrives at the Didymos binary system whatever it encounters will be within the range of properties already tested.

“We don’t know what Hera will find on Dimorphos’ surface, so we have to test lots of synthetic images to try to guess what it will see and to trial different ways of navigating using cameras alone. Self-driving cars use the same idea of vision based navigation with a camera to explore the environment,” explains Manuel Sanchez Gestido, the Technical Officer at ESA in charge of the project.

Initially, the software was only developed for cameras looking at normal light ranges, but recently Versions 6 and 7 will be implemented to generate images as if from thermal infrared cameras.

Iterating technologies as tools, components and infrastructure progress is one way GSTP and TDE help progress space exploration and is vital to improving the meteoroid models needed for future Earth, space and Lunar situational awareness programmes. Each version of PANGU has been funded through a GSTP contract with the University of Dundee, UK, and the team are currently working on upgrades that will ultimately become version 8.

“We’re looking at introducing an event-based neuromorphic camera, the same as those used in self-driving cars. We haven’t resolved it yet but it’s a promising technique,” Manuel Sanchez Gestido adds.