'Sojourner' was the first successful rover mission on mars which landed on 4th July 1997. It was designed to last for 7 Mars days and could be extended up to 30 Mars days. Sojourner lasted for 83 days on mars(85 Earth days.)

This was followed by Rovers: 'Spirit' and 'Opportunity'. The Spirit’s mission was planned for 90 Martian solar days(92 earth days) but because of winds cleaning the sand over its solar panels, it was able to continue the mission for six years. Opportunity rover was operating from 2004 up until 2018 and traveled just over 45 km.

It's been said that ‘what a rover could do in 6 months, a Man can do in 2 hours.’ If this holds true, A man could have done the same in less than 2 days. But rovers have also allowed us to discover key ingredients to life such as oxygen, nitrogen, hydrogen, carbon, sulfur and they have also measured radiation levels on Mars so that when we send humans, we already have a better understanding of the environmental conditions that we will be exposed to.

Rover Spirit was stuck in a region of soft soil during its mission on the surface. In order to get Spirit unstuck, Engineers from NASA's Jet Propulsion Laboratory had to put an identical rover on Earth in as close to the same situation as possible including a reduction in gravity.

This highlights an advantage of human consciousness against a machine running with codes. In addition, A human would not have to wait for signals from Earth to make the decisions to get out of a complex situation. These signals take anywhere from 4 minutes to 24 minutes depending on the distance from Earth to Mars. (Closest: 54,556,762 km and Farthest 400,762,656 km)

If we send humans to Mars, we can rapidly conduct our experiments and discover possibilities of staying on the surface. We can drill the Martian polar ice caps to look into its past and seek martian life even if it exists in a microscopic form. We will also be able to find out if liquid water exists below the surface and possibly use the same in the future for humans staying on the Red Planet. 

The Sun is a Giant Bright celestial object of intense nuclear energy. It unleashes billions of tonnes of electromagnetically charged plasma hurtling into space causing what we know as 'solar storms'.

Coronal Mass Ejections (CMEs)

It is a phenomenon in which a large amount of magnetized plasma is released into space from the surface of the Sun. The matter which shoots off into space largely consists of electrons and protons with an average mass of 1.6 x 1012 kg with up to a speed of 3200 km/s as observed by Solar and Heliospheric Observatory(SOHO). At these speeds, These ejections take several days to travel to earth. But the fastest ever recorded was in 1859 during what we refer to as the ‘Carrington Event’. 

What Causes CMEs?

Plasma on the surface of the Sun is an extremely good conductor of electricity and is highly affected by magnetism. The sunspots on the surface of the Sun are the regions where the magnetic fields get tangled. The Size of the sunspots can be anywhere between 15 km to 160000 km(multiple Earths can fit into it). Such enormous changes and disturbances in the magnetic field result in ‘Magnetic Reconnection’. Which converts magnetic energy into Kinetic energy, Thermal energy, and accelerates particles into space. 

How do we see it?

The Sun is the brightest object in our skies, and observing the surface of such a bright celestial body isn’t possible without special equipment. ‘Coronagraph’ instruments are used as an attachment to the telescopes which is designed to block out the glare of stars to resolve the nearby objects. The ‘corona’ which is an aura of plasma extending millions of kilometers into space surrounding our sun is observed with the same technology. 

Earths Magnetic field and CMEs

The Earth has its own magnetic field around the planet. When the Earth is hit by a CME, it is known as ‘Geomagnetic’ or ‘solar storm’. The force of the CME compresses the Earth’s magnetic fields for the duration of this storm. 

When the solar storm originating from CMEs hit Earth's magnetic field, the particles are directed towards the poles. These particles which are mainly electrons and protons, are considered to be the main cause of beautiful lights being generated in Earth’s atmosphere known as ‘Aurora’ or ‘Polar Lights’.

The Carrington Event

It is the most intense geomagnetic storm recorded in the history of mankind. Midday on 1st September 1859, Amateur astronomers Richard Carrington and Richard Hodgson recorded the intense solar flares. During this geomagnetic storm, the CMEs had traveled 150 million kilometers to Earth in just 17.6 hours. 

The auroras were seen all around the globe during this solar storm and could be seen from some regions along the equator. The electrically charged particles from the sun entered Earth's atmosphere and surged telegraph systems causing them to fail. Some events of electric shocks were also reported by the people operating the equipment and some operators could still send and receive signals even after disconnecting their power supplies. 

One more CME hit earth in March 1989, less devastating than the 1859 incident which jammed radio stations and rendered the satellites in orbit useless for hours. 

If today we are hit by CME as powerful as in 1859, It can cause devastation because a large part of our lives is surrounded by technologies driven by electricity. The most susceptible targets being Electricity grids and transformers if turned off can affect billions of people on Earth causing all sorts of issues including Manufacturing, Transportation, Food Production. 

Mankind as a whole is shockingly unprepared for a natural disaster caused by super solar storms of such magnitude.

There is a lot that goes on from the ‘rocket launch’ to ‘docking on the space station’ which is already figured out days before the launch. Understanding orbital mechanics is essential for rocket science. 

Step 1: Getting astronauts above the atmosphere 

The Rocket to which Astronauts are strapped, helps them leave the planet’s dense atmosphere and inserts them into an orbit that does not have much of a drag due to the atmosphere. This altitude ensures that the astronauts with the docking vehicle won’t fall back down on earth. The third stage of the rocket cuts off in this ‘Insertion Orbit’ and the astronauts are no longer in a rocket-powered flight. 

Step 2: Hohmann Transfer

It is the most efficient way to move a spacecraft from one circular orbit to another circular orbit with either smaller or larger radii. This orbital maneuver consists of 2 circular orbits(one of which is the destination orbit) and 1 elliptical orbit(Connecting the 2 circular orbits)

Phasing Orbit: The docking module uses its thrusters to increase its tangential velocity which in turn puts the module in an elliptical orbit. This burn of thrusters is performed on one side of the planet and the new elliptical orbit intersects the destination-circular orbit on another side of the planet. Once the module reaches this intersection, it turns on the thrusters again to make its elliptical orbit a circular one(This is Phasing Orbit about 370 km above Earth). This maneuver is known as ‘Hohmann Transfer’ where module waits for the correct location of the Space Station to initiate the next maneuver. 

Step 3: Bielliptical Transfer

This is the orbital maneuver that transfers the docking module from Phasing Orbit to final Spacestation orbit with three engine burns. The first 2 burns put the module in space station orbit and the last burn is a series of correction burns to ensure the right speed and right location with respect to the Space Station. 

Now the Module is ready to make a U-turn in space to face the space station for the docking phase. 

Step 4: Docking

This phase involves aligning the docking module axis to the space station axis while simultaneously closing the distance between the module and ISS. The second step of this phase is to align the module to the correct docking port of ISS. Once this step is concluded, the astronaut crew issues command for the final approach. 

1. The Probe touches the Docking Hatch.

2. Thrusters provide one last push to ensure the lock.

3. Module assembles with ISS.

4. Docking interface Pressure checks. 

5. Pressure Equalisation. 

   

After all the above steps, The Hatch finally opens and the astronauts are welcomed aboard International Space stations with Hugs and High Fives.

About 65 million years ago, the world of dinosaurs was destroyed by an asteroid about 10 km wide. Such size of an asteroid can have global effects because of the debris it ejects on the powerful impact. It can spread dust clouds over the entire planet and block out sunlight from reaching the surface causing a catastrophe. 

There are over 24,000 near-earth objects detected until now which pose a serious threat to us. One great example of this is the ‘Chelyabinsk meteor’(20m wide), which entered the Earth’s atmosphere over Russia on 15th February 2013. It exploded in the air about 30km high and was brighter than the Sun for a brief moment. The shockwave generated by this blast injured over 1400 people and damaged around 7200 buildings in 6 cities in the region. 

Bomb an Asteroid

Send an explosive rocket system onto a trajectory that meets the asteroid in its path and then detonate the explosives causing the asteroid to blow up. This will turn the asteroid into a rubble pile but if the explosion is not massive enough, the gravitational attraction between these new fragments can still pull everything together. And now we will have an asteroid rain instead of an asteroid hitting the surface in one place.  

Attach a rocket to an asteroid

This involves placing the rocket propulsion on the surface of the asteroid and changing its trajectory just enough such that it misses the earth and flies past it. This is considering that the asteroid is completely a solid body and not collective fragments in which case, the rocket systems can only push one fragment that it is attached to. Even if the asteroid is a complete body, It rotates around its center of mass and so the rocket attached to its surface will be rotating with it making it more complicated to propel it in the desired direction in the required time. 

Using Gravity Tractor

One clever way is to use the gravitational attraction between the spacecraft and asteroid to move it away from the path to the collision. Park the spacecraft near an asteroid instead of landing on its surface, the gravity pulls both these objects together but the spacecraft with thrusters onboard can counter this force and ultimately only the asteroid moves towards the spacecraft pulling it out of the collision trajectory. 

Put a Reflective layer on the asteroid

Cover the surface of the Asteroid with a highly reflective foil such that the side facing towards the sun will have a large number of photons of light impacting the asteroid and reflecting back into space. This will create an equal and opposite force on the asteroid forcing it to move away from the Sun and essentially changing its trajectory of collision with earth. 

Using Powerful Lasers 

Lasers can be used as a powerful weapon against incoming asteroids. The idea is to point the laser on the surface of the asteroid and obliterate it at a point opposite to which it needs to be propelled. This point ejects debris into space and as an equal and opposite reaction to this, the asteroid moves away from its trajectory. The only requirement is to have powerful enough laser systems which we currently do not have.

The Bluish-grey giant is fallen over its axis and is rolling on the plane of the solar system. There are some fascinating facts about this cold world that makes it a unique place in our solar system. 

A Bit of History

The observation was reported by William Herchel on 26 April 1781 as a comet but was accepted globally to be a planet by 1783. It is the only planet in our solar system that is named after the Greek God of the sky(Ouronus). Every Other planet is named after a Roman God. 

Voyager 2 is the only spacecraft up until today to investigate the planet Uranus up close. On its closest approach, Voyager 2 reached 81,000 km above cloud tops of Uranus while studying 5 major moons and also discovered 10 new natural satellites around the planet. It also examined 9 known rings of the planet and discovered 2 new rings. 

Place in the solar system

The average orbit distance of Uranus is 20 times the distance of Earth from the Sun. At this Distance, Light from the Sun takes 2 hours and 40 minutes to reach the planet. The difference between the closest point and farthest point of Uranus from the Sun is 1.8 AU, Greater than any other planet in our planetary system. 

Uranus completes one revolution around the Sun every 84 years and rotates around its own axis in about 17 hours, 14 minutes. The rotational axis of Uranus is tilted by 97 degrees such that, while other planets spin inside the plane of the solar system, Uranus rolls on this plane. 

Uranian Natural Satellites

The Moons of Uranus are named after figures of English literature. There are a total of 27 known natural satellites orbiting Uranus. And these moons are differentiated into 3 categories:  

Puck is the largest of the inner moons at around 160 km in diameter. On the other hand, Titania is the largest of Major moons and the 8th largest in our solar system with 1578 km in diameter. The axial tilt of these major moons is the same as the host planet. The irregular moons are much further out in the orbit of Uranus and are highly considered to be captured moons with the biggest: Sycorax with around 200 km diameter. 

Key facts

• The pressure at the base of the mantel of Uranus is enough to compress carbon atoms into diamonds. It is believed that there are liquid oceans diamonds at the bottom of the mantel. 

• The uranian natural Satellite system is least massive if compared to other Gas Giants in our solar system. The combined mass of 5 major moons of Uranus is less than the mass of Triton: The largest moon of Neptune.

This volcanic world is a result of a constant tug-of-war between Jupiter’s powerful gravity and orbital resonance of Galilean moons and is responsible for the gas giant’s massive magnetic field.