Alok Ratheesh's Mars Endeavour satellite
Grade 11th,Sunrise English Private School,UAE

Why this name?
One of human kind’s greatest endeavors in the 21st century has been to go and live on other planets. This also encourages young bright minds like or better than me to aim for the stars and learn to get creative.

A brief description of the mission
This mission aims to provide support and assistance for humanity's greatest endeavor; living on another planet or more specifically terraforming and colonizing Mars to be our second earth.

What makes this mission unique from the other Mars missions?

This is the first mission to mars carrying life to another planet.

Scientific Instruments
Martian Life Test (MLT)
The very specialty of this mission lies in the black box (Martian Life Test or MLT) located at the bottom of the satellite; the MLT contains the most exciting part of the mission. This part will be entering the Martian atmosphere and hopefully have a safe touch down on Martian soil. The MLT is covered by a heat shield material (aluminum) to withstand the immense heat that the MLT experiences on entering the Martian atmosphere. The MLT contains cyanobacteria whose growth is monitored. So why use cyanobacteria? Cyanobacteria are one of the ancient organisms on earth which converted CO2 to Oxygen (producing 106 to 107 mol of oxygen per cm per day) about 2.4 billion years ago. The same could be done on mars. Since the cruise time to mars will take approx. 9 months which could be reduced even further by the X3 ion thrusters, we would have to ensure that the cyanobacteria get sufficient sunlight and a bit of oxygen to survive; the main UV radiation can be produced artificially and a small oxygen tank would release a bit of oxygen and the rest will be controlled by the bacterium which will maintain the O2 level in MLT.

Upon landing on Mars the outer heat shield will be removed and during descent a parachute will be deployed which is in the red part. The MLT’s inside is covered by glass to allow enough sunlight to reach the cyanobacteria and a small hole will be opened from which CO2 can enter the chamber and O2 can exit the chamber. If this works out successfully we could break the glass and let cyanobacteria start its life on another planet. Furthermore we could even make the cyanobacteria more suited for mars by genetically engineering it to produce even more O2 and survive harsh climatic conditions of mars.

Martian Atmospheric Survey (MAS)
Martian Atmospheric Survey (MAS) is an on-board scientific instrument used to detect the variation in Mars’ climate and weather conditions. Since, if we are planning to go to Mars one day we must study its atmosphere in depth so that we know what to expect and how to deal with climate problems if any.

This device consists of two open cubical slits through which the atmospheric particles can enter into a chamber for detecting the composition of the Martian Atmosphere. It also has a thermometer used to detect the heat and a barometer to detect the pressure level at a given altitude. The MAS also has an on-board gas detector and we can thus know the percent of composition of the gases in the Martian atmosphere. This can also check if the cyanobacteria have contributed to any increase in O2 content over time, we could also approximate the population of cyanobacteria (Since we could measure its average life span and the amount of O2 produced within the life span). The data collected will be sent back to earth ground station through the High gain Antenna.

Mars Colour Image processor (MCIP)
The Mars Colour Image processor (MCIP) takes the picture of mars in Red, Green and Blue and combines the RGB colours to get a coloured Image of mars. This camera can also take images in the far infrared and small UV wavelengths. The UV radiation will show how much UV radiation gets absorbed by the thin atmosphere; also it can be used to study the soil contents on mars and if it could harbor any life as we know it, or maybe even be suitable for plants to grow.

The Infrared Images can show the pattern of heating on the Martian surface, this can later be used to study the wind direction and wind speeds. Furthermore, the infrared images can help map out the surface temperature of mars and this data can help choose a suitable warm enough spot on mars (mostly on the equator) for releasing the MLT containing cyanobacteria, since cyanobacteria can survive in temperatures as low as −20°C. Therefore landing in the equator region is the most appealing way to allow cyanobacteria to grow on mars and fix oxygen.

Mars High Resolution Imaging Camera (MHRIC)
The Mars High Resolution Imaging Camera (MHRIC) is a special camera with a telescopic lens, able to take very high resolution images of mars to better help scientists to study the topography and structures of small objects. These high resolution images can further help mars rovers to decide their landing site and exploration sites, acting as eyes for future mars missions and mars colonies. During its Mars orbit insertion configuration, when the probe will have its high resolution camera pointed towards the vast universe; MHRIC could take a very good resolution image of the vast universe. The camera can see in visible light and infrared; furthermore it could act as a space telescope during the cruise stage of the flight.

Radar Terrain Scanning Device (RTSD)
The Radar Terrain Scanning Device (RTSD) located at the front of the satellite and pointing towards the Martian soil, serves the purpose of terrain mapping by using radio waves. It works on the same principle as Radars on earth; the transmitter sends out radio waves which upon hitting the Martian soil gets reflected back and the return wave is concentrated at the focal point of the dish (since the dish is concave in shape) where the receiver is located. Why use radio waves? Well, for many reasons. First, Radio waves are electromagnetic waves meaning they don’t need a medium to propagate i.e. they can travel through space. Secondly, it has the largest wavelength in the electromagnetic spectrum; meaning it does not get scattered easily and can go through the Martian soil up to a few kilometers.

The frequency of the radio waves can be controlled either automatically by the onboard computer or manually by overriding it from Earth ground stations. If the speed of propagation is known (which is the speed of light) and the time taken for the return signal to reach the receiver is known (which can be measured); we can know the distance the radio wave traveled, thus giving us information of not just the position of the satellite but also the presence of valleys or hills on mars. Furthermore, by increasing the radio wave frequency >30MHz the radio waves can go through the Martian soil’ helping us detect the presence of water ice beneath the soil. This has been used onboard the Mars perseverance rover; however it can only scan to a very limited range and add that to its speed at which it moves, it takes a lot of time to scan the whole Martian underground for presence of water.

Communication Systems
High Gain Antenna

The High gain antenna works as a primary source of communication to and from the Mars Endeavor satellite (MEs). It consist of an amplifier which amplifies the radio waves before sending it back to earth as focused waves so that it can be easily detected back on here on earth; a radio transmitter which converts the data collected from the instruments onboard MEs into binary code (1s and 0s) and sends it back to earth; a radio receiver which converts the binary code received from earth into data which is sends the instructions to the onboard instruments. Since the High Gain antenna always has to point to earth for communication, it has moving parts and gimbal mechanics to orient the antenna to earth at all times during the mission.

Low Gain Antenna
There are 3 onboard Low gain antennas which function as an emergency communication medium. The disadvantage of low gain antenna over high gain antenna is that it transmits radio waves in all directions making it hard to detect on Earth and only fewer data would reach earth. However, we can use the low gain antenna to establish a communication link with ground stations because if we receive some signals from the low gain antenna we can know the position of the satellite and then we can orient the high gain antenna towards the ground station with great accuracy and establish a high communication link; thus being able to send a lot of information from the MEs to Earth. They also have the ability to move by using the paranoid shaped bottom to orient itself in the required direction. Though only 2 low gain antennas are required to establish a communication link, 3 have been added in case 1 fails to function.

Propulsion system
Electrical Propulsion
Why is an electrical propulsion system used on MEs? The ion thrusters are far better than the conventional chemical propellants since it is safer and more fuel efficient than its counterpart. Not just that the ion thrusters produced a higher exhaust velocity of ions than traditional chemical propellants; since they have higher exhaust velocities lesser fuel is required. Even though the thrust produced is considerably lower than that of the chemical propellants; ion thrusters can be used for a long period of time spanning from weeks to months of continuous use to compensate for the low thrust. This can cut down the time taken to reach mars considerably making it perfectly suited for the mission carrying life to mars. It is a type of Hall-effect thruster which works on releasing the propellant (xenon) at high speeds accelerated by magnetic and electric fields. It gets its required electricity from the solar panels which will convert sunlight into electrical energy for use mostly to the X3 ion thruster during the cruise stage.

Chemical Propellant
First question which comes to mind is why are we using a chemical propellant when there is an electric propulsion system? The answer is simple, it is used for the most important and difficult task in any mars mission i.e.: orbit insertion. As I had explained earlier the thrust produced by the X3 ion thruster is very low and this force is not enough for an orbit insertion maneuver. The chemical propellant on the other hand can produce high thrust in a shorter time thus making it ideal for use in orbit insertion.

It uses hydrazine as the fuel (liquid fuel) and di- nitrogen tetroxide (N2O4) as the oxidizer. When these are mixed it forms a hypergolic mixture (meaning that it does not require an igniter for combustion); they come in contact with each other in the combustion chamber and only the required amount of gas is released so that the whole propellant is not used up in one go. Hydrazine is used since it has a high thrust (~20N).

Orbit Insertion
It is the process through which the satellite is put into the Martian orbit manually. The satellite is slowed down by doing many aerobrake maneuvers forming an elliptical orbit around mars extending to the low mars orbit and the other end in deep space. The atmospheric drag of mars (even though less than that of earth) can help slow down the satellite considerably after performing many air brakes with the help of 3 retrorockets located at the front side of the satellite.

During orbit insertion the satellite will undergo an orbit insertion maneuver where it will do an 1800 flip which will make the chemical rocket thrusters pointed towards mars. The orientation can be achieved by firing the 2 two-axis rocket thrusters on the side and then stabilizing it by firing the other 2 two-axis rocket thrusters on the opposite side.

Source of Power for the mission
Solar Panels
The solar panels are the main source of power for the MEs and for the X3 ion thrusters during the cruise stage. The solar panels used have a very good efficiency, able to convert 23%-26% of the sunlight to electricity which is really great. With the length of the solar panel almost covering the whole length of the satellite; it can produce sufficient electricity required for the onboard instruments. The Solar panels are connected to the main body structure by a gimbal mechanic through which it can orient the solar panels to the direction of sunlight. The element used in solar panels is mostly silicon having 4 outermost electrons and another element such as Boron or Phosphorus so as to have a +ve and -ve end; upon absorbing energy in the form of light the electrons start moving and producing an electrical current. It does the opposite function of LEDs which convert electricity to light.

Nickel-Hydrogen Rechargeable batteries
Inside the cuboidal structure of the MEs lays the power source for the on-board instruments and navigation, guidance and control computer when in the shadow region (i.e.: when the sun is blocked by mars during orbit). The MEs draws its power from the sun during the day time a small amount of electricity is used to recharge the Ni-H batteries without affecting the energy requirement of other components. Lithium ion batteries are not used since they are heavier than Ni-H batteries. Even though Ni-H batteries have only one-third of the energy density of Li-ion batteries; Ni-H batteries last longer making it ideal for a long term mars mission which will stay in orbit around mars for many years.

Radioisotope thermoelectric generator
A small RTG is used to power the satellite in case of any solar panel failure. It uses the element Plutonium-238 to provide electricity. Note that this is going to be used mostly in case of solar panel failure or malfunction; or if the Ni-H batteries have not been charged properly.

Onboard computers
Navigation, Guidance and Control Computer
An onboard Navigation, Guidance and Control Computer is used in the mission and acts as the brain of the whole satellite. It is used to help navigate and guide the MEs to reach mars and do orbit insertion successfully. It has pre-built coding instructions that it will follow to reach to mars; new instructions can be given from earth to the MEs which is sent to the computer from the High Gain antenna (which receives the code from a ground station on earth).

The main functions are:-

  • It maintains and manages the data from ground stations and from other instruments. After sending the data back to earth, the unnecessary data is removed/destroyed.
  • It controls the amount of solar energy to be distributed to other instruments and for recharging the Ni-H batteries.
  • It calculates where it is with respect to mars.
  • It gives command (received from earth) when to release the MLT; and the functioning of other onboard instruments is monitored and maintained.
Possible launch windows to Mars in 2020 are between July and September.

Since planning a space mission takes considerable amount of time, mathematical calculations and simulations spent upon planning the trajectories for a transfer orbit and space flight plan including looking for a launch window to successfully get the satellite into Martian orbit; I have not included the calculation part of the mission and rather have focused on its structural and functional features of the satellite.

For more information on why Cyanobacteria are used in the mission refer to the following astrobiology research paper that I found online - Click here