Pulling off a safe landing on asteroids isn’t easy. Even though there have been some successful attempts lately, there have also been some notable failures – like the Philae lander on 67P/Churyumov-Gerasimenko. Granted, that was trying to land on a comet, not an asteroid, but the challenges are quite similar. One major hurdle is dealing with the uneven gravity on these bodies.
To deal with this issue, scientists from the Harbin Institute of Technology in China recently published a paper outlining a plan for pulling off “soft landings” on asteroids. This could make it a lot easier to explore these rocky worlds.
What separates a hard and a soft landing?
Let’s start by breaking down the contrast between a “hard” landing and a “soft” landing. A hard landing happens when the spacecraft descends—whether in a controlled or uncontrolled way—and makes contact with the asteroid’s surface with some force.
Usually, this results in a bit of damage to both the asteroid and possibly even the lander. Up to now, all the successful landings on asteroids have been “hard,” but some of them used something like a grappling hook to attach to the rocky surface and lower themselves down. On the flip side, a “soft” landing involves a probe gently descending to the asteroid’s surface, touching down with minimal impact and causing little to no disturbance in the surroundings.
On asteroids, this doesn’t cost much in terms of fuel because the gravity, and consequently the force needed to stay above them, is tiny on these worlds. But even that small amount of gravity can pose challenges during landings. That’s because gravity changes a lot depending on different physical features of the asteroids, like their shape, the density or materials in different parts of the asteroid, and how fast it’s spinning.
Also Read: Is living on Mars really possible or just a far-fetched dream?
A dire need for an algortihm
Coming up with an algorithm that can use all that data as input and figure out a solid plan for a soft landing routine has been a challenge for our robotic explorers on these small worlds. They haven’t quite cracked it yet.
Wenyu Feng and their team believe they’ve come up with a plan for this. In the first section of their paper, they go over earlier techniques for grasping the “uneven” gravity on possible asteroid landing sites, like representing the asteroid as a polyhedron and giving each face of the polyhedron its own gravitational constant.
Even though that might seem like a smart fix, it’s both demanding on power and takes a lot of time. Applying such an algorithm for in-flight adjustments is quite a challenge, to put it mildly.
Other models face similar issues, like struggling to accurately model the gravitational fields near the asteroid’s surface or needing extensive advance knowledge of the asteroid’s mass for precise trajectory calculations.
Artificial intelligence could make it possible
In the paper, the researchers suggest a different approach that taps into recent advancements in artificial intelligence. This method accurately models the gravitational field by leveraging data from different asteroid exploration missions. It then applies this model to predict the gravitational fields on a new target asteroid, all using the computational power onboard the probe.
Up until now, their work has been purely theoretical – they haven’t put their model or some of the foundational data through real-world testing. But, as the paper emphasizes, this effort is just one of many emerging in the realm of asteroid exploration.
The success of those missions with “hard landings” has clearly motivated a fresh wave of asteroid explorers. With this new data-driven approach to engage with them, we’re optimistic about achieving more successful interactions between robots and asteroids. Who knows, it might eventually pave the way for the first-ever gentle touchdown on one of the countless small worlds in our solar system.
Also Read: What does ISRO have in store for the future?
Asteroids could be home to ultra-heavy metals
Some astronomers speculate that specific asteroids might harbor an even grander treasure: ultra-heavy elements. We’re delving into elements that extend far beyond Uranium on our trusty periodic table. If these elusive elements exist out there, they would be so weighty that in the Earth’s early days, they likely plunged straight down to the core, explaining why we’ve never unearthed them here. Discovering them would be a jaw-dropping revelation, but it might also be the unobtanium of science fiction sagas.
The idea of ultra-heavy elements springs from theoretical models involving colossal atomic nuclei. Elements beyond iron (with an atomic number z=26) don’t come to life through fusion within stellar cores; instead, they emerge from monumental events such as supernovae explosions and the collisions of neutron stars.
That encompasses all the valuable goodies like silver, gold, tin, and lead, reaching up to uranium with an atomic number of 92. Elements beyond uranium might exist in nature, but we’ve never stumbled upon them in the wild. This is partly because, after lead, only thorium (z=90) boasts a stable isotope. Uranium persists for a few billion years, plutonium (z=94) holds on for around 80 million years, and americium (z=95) only lingers for 7,000 years.
Beyond that point, these elements have half-lives lasting only a few days at most, sometimes mere seconds or milliseconds. The truly hefty nuclei aren’t radioactively stable, so even if they occur naturally, they don’t casually hang around in asteroids for billions of years. Yet, delving into the theoretical calculations for massive nuclei indicates that well beyond uranium, at approximately z=114, there could be a sweet spot of stable elements. These would exhibit a “magic number” of protons and neutrons, neatly filling nuclear shells and rendering them exceptionally stable.
The notion of the island of stability is widely accepted, but the majority of nuclear experts predict that the residents of this island will endure for no more than a century. Yet, some contend that they could boast half-lives comparable to uranium, spanning up to a billion years. If that holds true, elements like flerovium might just be loitering in those asteroids.
