HOW TO GET TO MARS TECHNICALLY

 

This is a short lesson in astrophysics.

Ok for those interested in learning the technical aspects of getting to Mars and also so not obvious technicalities. if not please Scroll down.

So to journey to Mars just for a robotic rover is extremely challenging . So this is exactly the same for humans it’s a matter of scale and adding weight for life support and therefore the extra weight of the fuel needed.

Technical simplified list of considerations just to get there.

1. Timing 

2. Weight/Mass

3. Fuel

4. Calculations 

5. Extra factors gravity slingshots or gravity assist.

6. Why haven’t we got there already.

7.  Extra consideration or facts 

1.TIMING

Ok what’s time got todo with it?? Short Answer a lot.

Consider this the earth orbits the sun at approximately 30 kilometers per second, (67,000 miles per hour). Taking obviously 1 earth year

Mars travels at: 24 kilometers per second (53,853 miles per hour), or a period of about 686.93 earth days.

How is this relevant?? Ok because both Earth and Mars orbit the common sun at different speeds and different days to complete a full orbit ; so the distance between there respective positions is vastly different .  

So we have to chose the place at which there closest, ah but it’s not that simple , consider how long it takes to get from earth to Mars at its closest .

The trip to Mars will take about seven months and about 300 million miles (480 million kilometers). Dang that’s a humongous distance.

Imagine this we have to set off 7 months before to arrive at the exact point in space with a few course corrections *.

Ok so that’s as short as I can get it

2.WEIGHT.

Hey things weight the same in space nothing , what’s weight got todo got todo with it ... ( Tina lol) 

Well even though you don’t have weight, because weight is relatively to gravity and mass.  So mass is the important factor here and is usually describe as Newtonian Mass. 

What’s Mass ? Mass Is the quantity of matter In a physical body. Also a measure of the body is inertia the resistance to acceleration (Change of the velocity) when a force is applied. 

Mass is also determined by the strength of its gravitational attraction to other the bodies.

Ok I’m confused??

So simply the mass of a 1kg object. 

Is 1kg on Earth and 1kg on the moon . 

But gravity is 6 times less on the moon hence, On the Moon, g = 1.6 N/kg. In other words, a 1 kg mass has a weight on the Moon of 1.6 N or 1/6 Kg= 0.16666r KG

So depending how much mass we are taking to Mars changes the amount of fuel we need to accelerate it up-to speed to get there in a timely fashion .

Einstein postulated there was no difference between a gravitational field and constant acceleration acting on a body.

3 FUEL 

How much fuel do we need to get this mass upto speed to reach the rendezvous point on time. This is what will make the task difficult.

Enough propellant to accelerate the craft upto a given speed then enough fuel todo coarse correction and reverse thrust to slow and enter orbit of Mars etc.

Conventional Rockets have a theoretical limitation associated with the expansion of the exhaust gases and the mass lost in the burn per second.

Possibly ion thrusters . This sounds science fiction but is actually fact. This is a gentle force but can accelerates mass upto the speed of plasma given enough time relative to mass.

This could be used as a second stage too the primary conventional rocketry. 

4 Calculations  

The calculations needed are possibly the most complex to solve. 

In order to work out the correct primary coarse trajectory we need to

Work out:-

A) The point we are in space orbit or the main payload.

😎 The point in space time we are to leave the earths orbit using earths intial speed. 

C) The speed of acceleration to the theoretical rendezvous  point . Speed after burn will be a relative constant at the end of burn and trajectory changes will be subject to other laws of astrophysics below.

D) Two Body or Three body problem, what’s that?? 

Ok with the advent of basic computers and the need to venture to the moon . It soon became clear that when the moon lander and the lem needed to get to the moon orbit in the same way we would get to Mars there where holes in how we calculate this impossible task.

The problem was this, the large celestial bodies say the sun, earth and moon perturbation are all moving in there respectively orbits relative to each other whilst as the same time are gravitational attracted and perturbed by each other in a dynamic and a feedback fashion. so to work out exactly where you are and will be was chaotic.  The spacecraft theoretically is the forth body but is considered to be more or less infinitely minuscule to effect the larger bodies so is excluded.

Non the less this was a massive problem.  Even NASA couldn’t solve this on its own. 

A single university phd graduate unbeknown to NASA booked computer time in order to form a solution to this problem.

Whilst the three body problem in general is unsolvable even with today’s super computers .

A few special cases as above have been solved . He extrapolated a Two body solution then  An extra solution consisted of a set of closed figure-eight trajectories that pass arbitrarily close to the two celestial objects. These are now known as ?Arenstorf Periodic Orbits.? 

In 1966, he was given the NASA Medal for Exceptional Scientific Achievement for his contribution.

Mars luckily can use fir the most part the two body problem which was first solved by Newton’s Newtonian laws . 

Coarse correction can also be sent for later minor rendezvous correction.

Why haven’t we got there already.  There are a number of reasons some technical and others ethical problems.

Technical the moon is a mere  approx 250,00 miles and todo that cost billion in 1966.  Mars is at the closest journey of 300 million miles with life support not robots.

With a seven month trip minimum and a wait time of two years before alignment and another 7 months return .  So three and a quarter year round trip ethically is this a suicide mission?

Lastly the technological advancement and sheer cost and validation of this expenditure both on a political and business level is probably the hardest of all.

7  Extra consideration or facts

Information overload, if you haven’t already gone into a coma with all this ? What else is there??

Other problems not understood well are .

Communication at a distance

Consider this when we look at the sun in the sky we don’t actually see it as it is but how it was and not where is it but where also it was 8 minutes ago.

Radio waves as with light travels at the speed of light which is constant and takes time.

Since the distance between earth orbit and the sun is more or less the same 8 mins is how long communication takes to arrive and the same to reply.

Unfortunately the earth and Mars depending on there orbits round the sun can range from 34 million miles to 249 million miles . So from 2.4 minutes to 20 minutes approximately one way .

So communicating has delays . So messages would have to be in the form of emails only.

Also controlling any robot or machine or craft in real time isn’t possible. So we need to anticipate in advance where craft or robots will be, wait for the result and change the coarse.

Or more common will be to use autonomous thinking craft or robots and AI.

To sum up going to Mars is as yet a theory and we have just considered to get there? Not what we do when there that’s a whole new volume not just a chapter.