First, I’ll confess I am not an expert in orbital mechanics by any stretch of the imagination—not even close. I don’t purport to be one, nor have I ever played one on television. So what follows is an amateur’s attempt to consider what it might take to get to Mars quickly.
I do, though, appreciate the simplicity of some of the equations that describe the mechanics of motion in our typical, everyday, non-relativistic (i.e., no Einstein in today’s post) universe. For example, in high school physics, I remember that the distance traveled from a standing stop is one-half the acceleration times the time squared (d = ½ a t2), where d equals the distance traveled, which equals the distance traveled acceleration and t equals the time.
So, what does this have to do with getting to Mars? Well, I thought I’d share a simplistic view of how to get there in a hurry. The equation tells us that even for vast distances, we can get there in a hurry if we can constantly accelerate. Imagine 0 to 60 in 4 seconds in a car—what if you kept going? You can get a sense of just how fast you’d be going in a relatively short period.
But before we go there, we might pause to consider that current plans to get to Mars involve journeys of seven to nine months or longer. This trip uses a tremendous amount of thrust to accelerate a space vehicle and get it started on its way. Then the spacecraft coasts for months. When it arrives at the Red Planet, it again expends fuel to slow down and either enter orbit or land. This is how Perseverance traveled to Mars, as did the array of landers and orbiters that are currently operating on and around Mars.
The question becomes, how would the journey to Mars change if we could continually accelerate for the whole trip. Those of you who are science fiction fans are likely familiar with The Expanse series. In that universe, the Epstein Drive provided constant acceleration. (Here’s some fan fiction: https://expanse.fandom.com/wiki/Epstein Drive.) If you watch the series, it appears to be 1 g (one Earth-normal gravity) since they walk around the ships normally.
That technology doesn’t exist—yet. Are we getting close, though, to constant acceleration at a lower level? That’s hard to say. But what if we could accelerate a ship at just 1/1000 of the force of gravity?
In that instance, and assuming we traveled to Mars when it was at its closest, the trip could be on the order of a couple of months. If we could accelerate at 1/100, it would be weeks. (Rocket scientists are very welcome to correct my math and assumptions.) Imagine a trip to Mars in a month. Colonization might seem more realistic. Return trips to Earth for a visit by Martians might be feasible. Maybe—a vacation at Olympus Mons or Utopia Planitia.
Regardless, as space technologies advance and we find new and different ways to build and move spacecraft, getting to and from Mars quickly might not stay a science fiction fantasy. In our lifetime, we just might see quick trips to our neighbor.
Let me know what you think? Would you go on a cruise to Phobos and Deimos with a stop at Jezero Crater to visit where NASA searches for past life on Mars? It might be fun.
Thanks for stopping by.
[Disclaimer: Please accept my apologies for any ads that pop up before the linked videos. They do not reflect my position, nor do I endorse any of the products – it’s just a YouTube thing I can’t get around.]
Steve,
Travel to Mars will be reduced to weeks sooner rather than later. Musk’s SpaceX space refueling changes everything. 400 feet tall is about as big as ships launched from Earth will ever be. More to the point, Earth launched ships will quickly become launches for orbital assembled ships because of space refueling. That’s because the larger the fuel tank, the faster and farther a ship travels. And, since the tank is refueled in space, there is no real limit to its size fuel wise. The larger the tank, the larger the ship. Expect ships by Mid Century exceeding the largest ships on the ocean that have enough fuel to continuously accelerate and decelerate, producing a pseudo gravity. It will have enormous fuel tanks to do that and take many many flights by refueling ships but Musk’s Space X expects to relaunch those refueling ships as soon as they’ve taken on their cargos of liquid oxygen and liquid methane. Eventually, it will take minutes.
Then, there are the compact, nuclear fusion reactors that M.I.T claims will be reality during this decade but that’s another story.
Thanks, Len. We are poised to see great changes in space travel. One key will be not only refueling in space but manufacturing the fuel in space – either from a comet like body or in lesser gravity well like the Moon. Boosting a few metric dones of liquid oxygen and hydrogen from the Moon takes less energy than from Earth. And if the water/ice is already in orbit – so much the better.
I imagine we’ll see a burgeoning of methods and processes over the next 10 to 20 years.
Buckle up.
Back in 1977 the role-playing game Traveller [https://en.wikipedia.org/wiki/Traveller_(role-playing_game)] was first published. It was written by total space geeks who worked out the mechanics for size of space craft, engine efficiency, fuel consumption versus volume and weight, ship travel time… it’s a great resource for “hard science” without requiring the engineering degree, but it’s meatier then the appetite of most.
One takeaway is that space is really inconveniently big and empty for our impatient consumer tastes.
Another is that achieving a constant 1G acceleration, followed by a flip-over and 1G deceleration solves a whole lot of misery.
An efficient electric engine such as the “Ram Augmented Interstellar Rocket (RAIR)” would be freaking awesome in this deployment (ref https://en.wikipedia.org/wiki/Bussard_ramjet).
Barton – thanks for the URLs and the info. I’m sure we’ll see a vast array of options. And I agree – a functioning Bussard ramjet would be freaking awesome.
Thanks.
All of you are way above me in the physics department…mind blowing…hope to be around to see and take advantage of the advancements….