Why Traveling to Mars is Hard

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Space travel, although rarely done with humans, is a multi-billion dollar industry, which affects the livelihood of thousands of people. With such an emphasis on an industry that keeps growing, the question comes up on why humans have not made it to Mars. After all, Moon landings happened over 50 years ago, which means Mars should have been next. However, the challenges to get to our red neighbor are many and most people do not dive deeply into them. I would argue the number one challenge is money as the cost to do this is beyond what anyone imagined in the 1970s. For the sake of argument, let’s push that aside and pretend there is funding for the project. What follows are the multitude of technological challenges to make this happen, each of which could create more economic opportunities, if solved. This article is for those who have not thought about the problem in detail.

Before I delve into this, you may be wondering, what qualifies me to write about the subject? My late uncle, Dr Pravin Mehta, worked on many of the space telescopes that orbited the Earth in the last century including the lens of the Hubble. My nephew, Sohum Udani, is wrapping up an internship with the Hayden Planetarium in NYC, which for those of you who follow the scene, know that it is directed by the great Neil deGrasse Tyson. Osmosis by nepotism aside, I have also written a few blogs on astronomy over the years on the subject of data analysis on my current employer’s web site. Besides, I like to discuss the subject.

Let’s take a look at the non-exhaustive list of technical challenges.

Time to Get There

This is the greatest technical challenge and today’s technologies do not solve this problem. It takes a minimum of six months to reach Mars. This was for the rovers, which are still wandering the planet. As payloads increase way beyond rovers and multi-stage orbiters are required for human transport, that time increases and will be more likely 9 months. To make this more complicated, because of the alignment of the Earth and Mars due to orbital mechanics, this “6 months” window to lift off and get to Mars only happens every couple of years. If the window is missed, we have to wait, otherwise, the time to get to Mars increases dramatically.

There are propulsion examples that are faster such as the Parker Space Probe that orbited the Sun, but this was boosted by a gravitational slingshot by the Sun itself and there is no way to achieve this method of propulsion to go to Mars with that method. What is needed is a way to cut the time to get to Mars to a quarter or even half of today’s limits to make this even conceivable. Even then, there will be a multitude of hurdles to overcome. To contrast with the Moon missions, it only took 3 days to get to the Moon, which allowed technology from 1969 to work. Increasing investments to increase propulsion should be the number one priority. This is a matter of energy and power. It has been suggested that nuclear powered propulsion is the next step for faster speeds for spacecraft, but this is untested, not built, and it may require some agreements to overcome treaties signed decades ago about restricting nuclear power in space vehicles. The hurdles for faster propulsion in itself has created a large market for research. One other thing to note is that just because something can go as fast as the Parker Space Probe (400,000 MPH) with yet to be invented technology towards Mars, does not mean there is an easy way to slow it down to orbit the planet without applying yet to be invented energy for “space brakes.”

Because this is a long term trip, if chemical fuels are being used, it will require a magnitude more capacity in fuel than was used for the Moon landings. This adds weight to the launch, which makes it require more powerful rockets. The other thing that will add weight to the launch is the size of the orbiter and attached lander and they will clearly not be as small as the Moon missions. Safely taking off from Earth with this much fuel and payload becomes another problem to solve.

Why Time To Travel Needs Reduction

I mentioned that the time to get to Mars is the biggest challenge to overcome. Why? It starts with exposure to radiation from cosmic rays. On Earth, the atmosphere blocks most of these cosmic rays produced by the Sun. The International Space Station (ISS) is built for long term housing and since it is so close to the Earth, it was not that difficult to to transport the heavier materials to build the station. Furthermore, the Van Allen Belt,? surrounding the Earth, protects against charged particles. Since the Moon voyages only took 3 days each way, exposure to cosmic rays was minimal compared to what may occur in a longer trip.

We already mentioned that the weight of the spacecraft is important because it cannot be so much that it hinders lift off. This means the spacecraft is not going to be made of 1 foot lead walls. A light weight material should be used that is strong enough to keep the structural integrity of the spacecraft intact, impenetrable to cosmic rays, and yet light enough to not hinder lift off and long term travel. This is a huge opportunity for the field of material science. If this problem is not solved, human travel would be severely hindered by cosmic rays. Even if the problem has been solved in theory, extensive long term real life testing would be needed before trying the approach with humans. Perhaps, sending mice (with robotic feeders) for a multi-month roundtrip to deep space would allow for testing the effects of cosmic rays in this new impenetrable hull.

The next concern is food and water for the 6 to 9 months trip. Although water that is not contaminated with dangerous chemicals can be made reusable with certain technologies, relying on this to always work can cause a major problem if this is the main way to re-manufacture water and the machine fails. This is easier to solve for the IIS due to the fact that they can receive new supplies from Earth. Let’s not forget that taking too much food and water will add to the volume and weight of the space craft. There must also be an ample supply for the return trip and for that I’ll discuss one possible solution later.

The concern that is hard to duplicate is loneliness and isolation, even when traveling with one or two companions. Unlike the ISS, there is no view of the Earth providing a psychological familiarity as what is seen while going away from the Earth is mostly blackness. Due to the speed of light, real-time communication with the Earth is not possible resulting in a delay, which could be anywhere from a few minutes to 24 minutes depending on the location of the spacecraft. Proceeding to email messages may make sense if the bandwidth for video and audio is not possible leading to more isolation. This feeling of loneliness, isolation, anxiety, and boredom should not be discounted.

The next problem with a long voyage is atrophy of muscles and changes affecting the eyes, both of which are not healthy. Unlike being in the ISS, there is no large body like the Earth providing some gravitational pull, which makes weightlessness a constant reminder of the trip. Spinning the spacecraft fast enough to simulate artificial gravity would cause other problems to be solved and will consume more energy. There is no reason to assume that this is going to be a healthy lifestyle for months on end.?

For all these reasons, cutting down the time of the trip is the most important step before even considering going to Mars with humans.

Landing

If you followed how the Moon landings occurred, you will remember that the spacecraft that got to the moon had two main parts, the orbiter which was the main spacecraft that circled the Moon, but never landed, and a lander that landed on the moon and then returned to the orbiter. The reason this was done was because it would be too difficult to land such a heavy spacecraft and then expect to take off again with enough energy to reach escape velocity. The latter would require more fuel.

The same approach would logically follow landing on Mars. The spacecraft would separate with an orbiter and humans would land with a landing craft. Here is where it becomes difficult again. Unlike the Moon,Maris is twice the size, meaning the same approaches for landing on the Moon will not work as gravitational forces are different. Landing a small 50 KG package with very little electronics using a parachute with no reason to assume it needs to fly again to get back to the orbiter is doable. However, landing with a lander full of humans, equipment, and supplies, with a need to fly again to return to the orbiter changes the whole approach.

As equipment got heavier and more sophisticated with the Mars landers, the approaches changed each time with many simulations done to ensure success. Airbags and parachutes were used in landing in which the lander bounced off the airbag more than once. The trickiness of these landings caused what was known as the “7 minutes of terror” as no communication was sent to Earth in that time and mission control had to wait those minutes to see if the lander landed unharmed. With current technology, there is no assurance that using a combination of airbags, parachutes, and reverse thrusters would work the first time. I would hope the first attempts at landing this type of lander would not have humans on board as success may need more than one take.

After Landing

Falling out of the sky at high speeds generates a lot of heat. Heat shields should protect the lander as this technology has been proven at a smaller scale for past rover landers and for the Earth’s reusable Space Shuttles. The thing about the Space Shuttles is after they land some of the shields are blackened to the point where they need to be replaced. This could be another problem to solve for the lander, but this is probably doable as the heat shields will not be needed for another landing assuming the final lander back to earth is a small capsule that lands in the ocean.

Mars has very little atmospheric pressure compared to the Earth and the prevalent air is mostly Carbon Dioxide. It is also dry and cold. It does have wind, resulting in dust storms and we would hope that the lander does not run into such a storm as that may damage, among other things, communication systems and any exposed thrusters. After surviving for months on a spacecraft, our astronauts will now have better gravity once they land safely. They will still have to wear their space suits to step outside due to the lack of oxygen, but just as importantly due to the lack of pressure, they’ll need their space suits pressurized to keep their blood from boiling and exploding. All the challenges of living in this environment can make the chances of survival bleak. Mars is not a hospitable place.

Since this was a mission planned decades in advance, we would hope that scout landers arrived near the landing site long before the humans got there. They would carry supplies needed for food, water, and fuel for any type of lengthy stay. The supplies would provide redundancy for the return trip for anything that was in short supply on the trip to Mars.

Here’s another thing to ponder. Because it has been 6 to 9 months since they left, the Earth is now further away from Mars because of orbital mechanics of different Sun rotation patterns. This means the astronauts cannot simply start their return trip home right away as they would have to wait lots of months before the Earth and Mars are optimally close together before lifting off again. I am not going to ponder on what it would be like to stay in such a hostile, cold, dry environment, but this adds to the discussion on why traveling to Mars is hard.??

Return Trip

The first question would be is the lander in good condition to lift off? If so, it needs to be designed to have enough propulsion to reach escape velocity, in which the energy needed will be more than anything that was used on the Moon. This has never been tested from Mars and we would hope the first attempts of this would be without humans using a drone lander. Once it reaches escape velocity, the lander needs to rendezvous with its orbiter to transport the astronauts back to the main spacecraft that takes them home. All of the challenges that were listed for the trip to Mars are repeated with an exhausted crew battling psychological darkness, muscle atrophy, and bombardment of cosmic rays.

Once the spacecraft gets close to the Earth’s atmosphere, the astronauts can crowd into a small capsule and be parachuted into the ocean to be picked up by a ship. This exercise has been repeated multiple times with the past Moon missions. It is getting to this point, which is the real challenge.

Conclusions

There are a multitude of steps to go to Mars and successfully return. I have only listed a handful of challenges as scientists who have studied this topic could easily point out many more. In order to make this into an article instead of a short book, I only laid out the highlights. As you can see, shortening the time it takes to get to Mars and return would be the number one problem to solve as that in itself diminishes the effects of other issues.

Going to Mars is worth doing as solving each set of problems opens up new doors to technologies that did not exist solving problems for the future beyond just going to Mars. It creates research opportunities, which may one day lead to mass production of much needed equipment (e.g., anti-muscle atrophy suit) opening up many jobs in the economy. I would hope each step is planned and tested. For instance, try to first send a spacecraft to Mars that orbits the planet and simply returns to earth’s orbit. Putting robots on board to simulate human behavior with mice or the equivalent may tell us lots of information including the effects of cosmic rays. The next steps would be to drop a drone lander on the next mission to see how successfully it lands and lifts off back to the orbiter. Each test tells us how the technology and procedures are working.

Of course, no amount of robotic tests or small mammal monitoring will simulate humans on a mission to Mars as one day the real mission will have to be attempted. Let’s hope everything that can be redundant is redundant and just about every scenario is accounted for with an answer. In the meantime, if you did not know it before, now you know that traveling to Mars is a hard problem to solve.