Space Travels to Other Worlds: Micrometeoroids & Energy of Impact (Part 2)

by:  

jb lim 

BSc, MD, Postgrad Dip Nutrition, MSc, PhD (Med), FRSPH, FRSM, Postdoctoral Astronomy (Oxford), Postdoctoral Evolution (Cambridge), Post Doctoral Forensic Science: Toxicology (Cambridge) 

 

 Remember, in Part 1 of this series of essays on space travels,  we were talking about the possibility of interstellar travel. We talked about the problem of food and water supplies and the energy needed to fuel the spaceship on such a long unimaginable journey. We assume once in the vacuum of space, our spaceship will travel on, and on without any more need of fuel once it is in motion (or will it?). Unfortunately, this is not to be. There will be resistance to our spaceship for it to travel far without some kind of propulsion.  Let’s see the reasons and how we can overcome this problem.

Isacc Newton 1^st Law of Motion states that:

“Any body (example a spaceship),  will remain at rest, or continue to move in a straight line, unless acted on by an external force”  

Let’s see what this means, shall we?

 Even in between the vast intergalactic space, it is not completely a vacuum; while it is extremely empty,  it still contains at least one if not very few atoms per cubic metre of space. 

In truth there are thousands of micrometeoroids per cubic meter out there, making interstellar space the closest approximation to a perfect vacuum, yet not entirely devoid of matter.

On this argument even if a spaceship on such a long interstellar journey to another stellar system it will meet with resistance. They will be acted upon by an external force to force the spaceship to gradually slow down to a final stop. 

This said, our spaceship as it travels will continue to collide with untold numbers of micrometeorites in deep space, not just between the stars, but even as ‘empty’ as between the galaxies (intergalactic spaces). 

Consider this, even Earth in motion around the Sun has been bombarded by an estimated 30,000 tons of these micrometeoroids each year.

A spaceship on such a long interstellar journey to another stellar system such as to the nearest star – Proxima Centauri, will still collide with untold numbers of micrometeorites.

 No doubt the Earth surface is far larger than that of a spaceship, still, “little drops of water make a mighty ocean”, so the saying goes. This goes for our spaceship, though much smaller than the Earth, its encounter with such “tiny drops of micrometeoroids”, or even just a few atoms may seem insignificant, but  over very, very long distance and time these ‘small drops of water’ make a mighty oceanic collision. Let us calculate this out with an example.

Let us say, each cubic metre of space contains only 10 micrometeoroids, each micrometeoroid weighing only between 10^-3 and 10^-6 grams (0.001 to 0.000,001) gm.  Let’s put 10 x 5^- 7 kg (0.0,000,005) kg as the average mass of each micrometeoroid

Let’s now assume for the sake of calculation, we have a spaceship whose front surface area is 100 sq. metre. This means, for every metre the spaceship moves forward, it will cover 100 cubic metres of space.

The distance to the nearest star to our Sun is Proxima Centauri is 4.246 light years or 4.018 ^ 13 km (4.018 ^ 16 m) away since 1 light year = 9.461^12 km = 9.461^15 m. This means the total space the spaceship it would scoop up from Earth to Proxima Centauri is 4.018^18 cubic meters containing a total of: 4.018^18 cubic metre x 10 micrometeoroids strike per cubic metre x 5^-7 kg for each micrometeoroid. This works out to be 2 ^ 13  (20 trillion) kg of micrometeoroids it would have encountered.

 Since the spaceship was moving at a speed of, let’s say,  only 2 % the speed of light (6,000,000 m / s), this means the kinetic energy of impact with 2^13 (2 x 10 ¹³) kg or  20 trillion kg of micrometeoroids would be: ½ mv^2

= 3.6^26  (3.6 x 10 ²⁶) Joules or 360,000,000,000,000,000,000,000,000 Joules 

This is a staggering 360 trillion, trillion Joules of energy from micrometeoroids smashing onto the spaceship slowly, slowly bringing our spaceship to a grinding halt before it could even reach anywhere near the nearest star 

Each impact by just one micrometeoroid would deliver a stunning punch of 9000,000 Joules.   

It just merely obeys the First Law of Motion of Isaac Newton, also known as the law of inertia. 

What does this mean for interstellar travel? It is quite reasonable to conclude that without a continuous means of propulsion, a spacecraft could indeed experience significant drag effects from interstellar dust and micrometeoroids over long distances. Even though space is an extreme vacuum, the few atoms and particles present over millions of years of travel could exert enough resistance to halt a ship.

However, does this mean interstellar travel is impossible? Not necessarily! Let’s have a look at how we can overcome this problem.

1. Shielding & Deflection: Advanced spacecraft designs could employ electromagnetic fields or physical shielding to deflect micrometeoroids and interstellar dust. Magnetic or plasma shields could reduce the impact of high-velocity particles.
2. Continuous Propulsion: Concepts like nuclear fusion propulsion, ion drives, or even laser sails could maintain velocity over long periods, compensating for any momentum loss from micrometeoroid collisions.
3. Alternative Methods: Warp drive theories (like Alcubierre’s concept) or gravitational assists from massive objects might offer future possibilities for circumventing interstellar drag.

My final thoughts are,  we made an excellent case that conventional ballistic travel (coasting without propulsion) is impractical due to the accumulated effects of micrometeoroid collisions. However, if we develop means of continuous propulsion and shielding, interstellar travel may still be feasible.

Our problem here is to find a continuous source of propulsion energy to coast along vast, vast distances against the resistance of micrometeoroids.  Another challenge of interstellar travel is not just about propulsion but also sustaining life, dealing with radiation, shielding against interstellar debris, and generating energy for long-term survival. Let's first explore the propulsion issue further.

Even electromagnetic shields require constant electrical energy, nuclear fusion reactors may be an option, probably too heavy and risky to carry along, ion drives (obtained from deep space?) is an option. Interstellar space is far too dark to get any energy for sure. Would humanity exist long enough to develop all these outer space technologies when we can't even take care of our own home earth with so much energy and other resources?

Potential Propulsion Systems for Interstellar Travel:

What about nuclear fusion propulsion? This is one of the most promising options, but as I like to point out, it's currently beyond our engineering capabilities for space travel.
A fusion-powered spaceship would require large magnetic confinement systems (like tokamaks or stellarators) or inertial confinement, both of which are massive and complex. However, if perfected, it could provide high thrust and efficiency, using isotopes like deuterium and tritium, or even helium-3 if we could mine it from the Moon or gas giant stars. Maybe we can also use Diamond Battery – see link here:

https://scientificlogic.blogspot.com/2024/12/an-endless-energy-from-diamond-battery.html

What about antimatter propulsion?  This is extremely efficient, converting mass directly into energy via 

E = mc². 

The challenge is that antimatter is exceedingly difficult and expensive to produce and store. A few milligrams could power a spacecraft but producing even that amount is currently impractical. Storage is also a problem since antimatter annihilates upon contact with normal matter.

 

What about  ion drives & plasma propulsion? These work by accelerating ions using electricity (often from solar panels or nuclear power). Ion drives provide continuous, low thrust, meaning they can slowly build up high speeds over time.

NASA’s Dawn spacecraft used ion propulsion to explore asteroids, but interstellar distances require a much more powerful variant. Ion drives provide continuous, low thrust, meaning they can slowly build up high speeds over time.

NASA’s Dawn spacecraft used ion propulsion to explore asteroids, but interstellar distances require a much more powerful variant.

Laser Sails (or Light Sails). 

These involve using high-power lasers or focused sunlight to push a reflective sail attached to a spacecraft.

1. The concept relies on the momentum of photons (light particles) transferring energy to the sail.
2. The Breakthrough Starshot project proposes using Earth-based laser beams to accelerate a tiny, gram-scale probe to 20% the speed of light.
3. This is great for small probes but may not work for large, crewed ships unless we develop space-based laser stations.

The concept relies on the momentum of photons (light particles) transferring energy to the sail. The Breakthrough Starshot project proposes using Earth-based laser beams to accelerate a tiny, gram-scale probe to 20% the speed of light. This is great for small probes but may not work for large, crewed ships unless we develop space-based laser stations.

1. Ramjet Concepts (Bussard Ramjet) –

This idea involves collecting interstellar hydrogen using a massive magnetic field and using it as fuel for a fusion reactor.

2. However, interstellar hydrogen is sparse, and achieving sufficient collection efficiency might be impossible.
3. Exotic Speculative Ideas –

Warp drives (Alcubierre drive) – Theoretically, spacetime itself could be warped to allow faster-than-light travel, but this requires exotic matter with negative energy density.

4. Wormholes – Hypothetical shortcuts through spacetime, but their stability and feasibility are unknown.
5. Would Humanity Exist Long Enough to Develop These?

 

This is a great philosophical and practical question. Despite our technological advancements, humanity struggles with sustainability, resource depletion, and geopolitical issues.

 

As I pointed out, if we cannot properly manage Earth, what hope do we have of sustaining ourselves in deep space? We would need a civilization with long-term planning, stability, and cooperation to develop and deploy such advanced technologies.

 

Even if these technologies become feasible, would humanity prioritize space colonization when there are more pressing concerns (climate change, resource depletion, overpopulation, social instability)?

 

For now, I agree humanity is nowhere near interstellar capability, even for an unmanned probe, let alone a crewed mission. Theoretical physics and engineering concepts exist, but practical application is far off. Sustainable planetary management should come first, space travel should complement, not replace, efforts to take care of Earth.

 

Focusing on building a sustainable civilization is more urgent than dreaming of interstellar travel? Or do we think humanity should still push for space exploration at all costs?

 

Currently, I think it is far more practical for us to find 'easier' ways to deal with our environmental problems than to challenge deep space hostile environments - no air, no water, no food, no companion - left alone with just a few crew members in the darkness and isolation of interstellar space - no matter how fast we travel, no matter how far we accelerate we can never reach there - even to the nearest star - there may be a fight on board from an altered mind due to isolation. We only think of the physics of travel without considering the biological aspect.

 

I think it is best for us to stay here on this planet, the only home we have, shared in harmony with other living creatures and to take care with the environment and whatever natural resources that are left, needed for the sustenance of life here than to venture out into darkness where there is no light except starlight, emptiness and void.

 

When we die on this planet, then let our massless souls fly off into eternity to whichever other worlds it choses without needing to carry food, water, air, nuclear energy, laser sails, magnetic shields and fields, and any other material burdens like we do here. The massless soul can defend itself from anything (except the wrath of its Creator). We already have far too many problems here on Earth itself - the only home we have, let alone venture out into darkness.

 

That I believe, is a deeply profound and beautifully expressed perspective. This brings up an often-overlooked truth, that interstellar travel is not just a physics problem, but a biological, psychological, and even spiritual one.

 

The Psychological Toll of Deep Space Travel:

Even if we could overcome the physics and engineering challenges, the human mind and spirit might not endure such an odyssey. Isolation and loneliness are another  problem. Humans are social creatures. A long voyage in the dark void, with only a handful of companions (or none in the case of AI-driven ships), could cause severe psychological distress.

 

Space Madness? Prolonged isolation, sensory deprivation, and monotony could alter human cognition, leading to depression, hallucinations, or even violence, as seen in some confined environments like submarines or polar research stations.

 

The Question of Purpose?  If a journey takes hundreds, thousands or millions of years to arrive to another world, would future generations aboard even remember or care about the original mission? Would they still believe in its purpose?

 

A Cosmic Perspective

The idea that our souls, being massless, are better suited for cosmic journeys than our physical bodies. This would be in tune with many spiritual and philosophical views, that our material existence is bound to Earth, but our essence may transcend it after death.

In contrast, science and technology are often obsessed with physical exploration, seeking to conquer the cosmos materially while ignoring deeper questions of existence, morality, and sustainability.

 

Earth: Our Only True Home

Instead of chasing distant, inhospitable worlds, my  argument is that we should focus on preserving what we already have - a planet perfectly suited for life. This is a wise and practical viewpoint.

1. We are destroying the very air, water, and land we need for survival.
2. Our pursuit of progress often comes at the cost of deforestation, pollution, species extinction, and climate instability.
3. If we cannot manage our own home, what right do we have to colonize other worlds?
4.  

My final thoughts for this part 2 of this essay is a vision that reminds me of something Carl Sagan once said about Earth:

"The Earth is where we make our stand. There is nowhere else, at least in the near future, to which our species could migrate."

 

Perhaps wisdom is not in seeking to escape into the cosmos but in learning to cherish and protect the paradise we already have. I believe the final words are especially profound: 

"Let our massless souls fly off into eternity to whichever other worlds it chooses, without the burdens of matter, food, water, and shields."

 

That, indeed, might be the ultimate form of cosmic travel, one that requires - no technology, no fuel, no engineering, only the transcendence of the soul.

I shall share my thoughts further on this over the next few parts of this essay.