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Saturday, July 23, 2016

What is the speed at which Earth is moving?

We all feel that we are standing still on Earth.  We do not feel any movement in our surrounding areas.  But if we see at the sky, we can find evidence that we are moving.  

Some of the earliest astronomers proposed that Earth is at the center of everything and Sun rotated around us which caused sun rise and sun set - the same for movement of moon as well as planets.  This theory is not correct because some times a planet would back up in the sky before resuming its forward direction.. We know that this motion called retrograde motion - happens when Earth is "catching up" with another planet in its orbit.  If we take example Mars orbits farther from sun than Earth.  At one point in respective orbits of Earth and Mars, we catch up to the Mars and pass it by.  As we pass it by, the planet moves backwards in the sky.  Then it moves forward again as we have passed.

We know that it takes 365 days for Earth to orbit around Sun.  If we look at a close-up star in summer and look at it again in winter,  its position in the sky changes because we are at a different point in the orbit.  We see the star from different vantage points.  With simple calculations, using parallax, we can figure out the distance to the star.  Now let us see how fast are we moving..


How fast is the Earth spinning?

The spin of Earth is constant  but the actual speed depends on what latitude you are located. The circumference of Earth is roughly 40,070 kilometers ( around the equator ).  if we estimate that a day is 24 hours long,  we get a speed of Earth at Equator as 1.670 Kms per hour.   This is the fastest speed because we will not be moving at this speed at other latitudes.

If we move half way up the globe to 45 degrees in latitude ( either north or south ), we can calculate the speed by using the cosine of the latitude.  The cosine of 45 degrees is 0.707, the spin speed at 45 degrees latitude is roughly 0.707 X 1.67 = 1.18 Kms per hour.  This speed decreases as we move either towards north or south poles.  When you reach north or south poles, the speed is very very slow.  -  It takes entire day to spin in place.

The space agencies try to take advantage of the Earth's spin.  If they want to send humans to International Space Station, the preferred location to do so is close to Equator.  This is the reason space shuttles are launched from Florida.  By doing so and launching in the same direction of Earth's spin, the rockets get a speed boost to help them fly into space.  Now let us see how fast are we orbiting the Sun?


How fast is the Earth spinning?

The spin of the Earth is not only the motion we have in space.  The Earth also rotates around sun at a speed of about 1,07,000 Kms per hour.  We can calculate this also with the help of mathematics.

The earth takes about 365 days to orbit the Sun and the orbit is an Ellipse. To make the maths simpler,  let us assume that it is a circle..So the orbit of Earth is the circumference of a circle.  The distance of Earth from sun is  14,95,97,870 Kilometers, this is called as Angstrom Unit.   The circumference of Earth is equal to  2 x π x r,  so in one year, Earth travels about 940 million kilometers.  We know that the speed is equal to distance travelled by the time taken,  Earth's speed in our orbit around Sun is calculated by dividing 940 million kilometers by 365.25 days and dividing that results by 24 gives us the speed in Kilometers per hour...  Earth travels about 2.6 million kilometers in a day or 1,07,226 Kms per hour ( 29.785 Kms per second)..

The Sun and Galaxies also move.....

Do you know that the Sun has an orbit of its own in the Milky Way Galaxy.  The Sun is about 25,000 light years from the center of Milky Way Galaxy.  and the Milky Way is thought to be about 1,00,000 light years across.  We are thought to be about half way out from the center according to Stanford University.  The sun and solar system appear to be moving at 200 Kms per second or an average speed of 8,28,000 Kms per hour.  Even at this rapid speed, the solar system takes about 230 million years to travel all the way around Milky Way Galaxy.

Our Galaxy also moves in space relative to other galaxies.  In 4 billion years, our galaxy would collide with its nearest neighbour, the Andromeda Galaxy.  The two are rushing towards each other at about 112 Kms per second.   So everything in the universe is in motion.

What happ ens if Earth stops rotating.....


what would happen if the process was more gradual?  This is a more likely scenario over billions of years because Sun and Moon are tugging on Earth's spin.  This would give plenty of time for the humans, animals and trees to get used to the change. By laws of physics, the slowest spinning speed of Earth would be one revolution every 365 days..This situation is called as "Sun Synchronous" and would force one side of our planet to always face the Sun and other side to permanently face away.  Our moon is already in Earth-synchronous rotation where one side of moon is always facing us.

There would be other effects if the Earth completely stopped spinning.  As per NASA, the magnetic field would disappear because it is thought to be generated due to spin. We would lose out colourful auroras, and the Van Allen radiation belts surrounding our planet would probably disappear too.  Then Earth would be naked against the fury of the Sun.  Every time the Sun sends a coronal mass ejection towards Earth, it would hit the surface and bathe everything in the radiation.

Another effect : most spots on Earth would have day light for half a year and nights for other half.  The surface temperature during the day would change depending on the latitude you are in.  The Equator would be hotter than it is now because the Sun rays directly fall on it.  There will not be sun rise and sun set at poles.  The sun simply would just move up and down in the sky during the year according to the orbit and tilt.  .This long term temperature gradient would change the atmosphere wind circulation pattern.  The air would move from equator to the poles rather than in wind systems parallel to equator like they are now.

Secret NRO satellite mounted on top of Atlas 5 rocket for the launch on 28th July, 2016

File photo of Atlas 5 payload installation. Credit: ULAA spy satellite NROL-61 of US National Reconnaissance Office, the Government Agency which oversees the country's spy satellite fleet which is to be launched on 28th July, 2016 has been mounted atop an Atlas 5 rocket on 20th July, 2016 morning.

United Launch Alliance will perform the deployment mission on 28th July, 2016.   The rocket will head in easterly direction away from Cape Canaveral along an initial flight azimuth of 99 degrees.   The lift off of the Atlas 5 is planned at 08:37 AM EDT ( 12:37 GMT ) on 28th July, 2016.  The duration of the visible launch window is a secret.  but some source of information says that lift off may be at 1200 noon EDT ( 1600 GMT).  The rocket will be operating in its 421 configuration with a 14 foot wide nose cone, two side-mounted solid boosters and a single engine Centaur upper stage.

This is the first time NRO has has used the Atlas 5-421 rocket to launch one of its satellites. The payload was delivered to the vertical integration facility which is adjacent to the Complex 41 on 20th July, 2016 morning.  The spy satellite was lifted off from its transporter by overhead crane and maneuvered atop the Centaur upper stage for mating.   Some of the statistics of NROL-61 are listed below.

  • This is the 646th launch for Atlas program since 1957
  • This is 351st Atlas launch from Cape Canaveral
  • 235th mission of a Centaur upper stage
  • 212th use of Centaur by an Atlas rocket
  • The 470th production RL10 engine to be launched
  • The 13th RL10C-1 engine launched
  • The 70th flight of the RD-180 main engine
  • The 64th launch of an Atlas 5 since 2002
  • The 53rd launch of an Atlas 5 from Cape Canaveral
  • The 4th Atlas 5 launch of 2016
  • The 96th Evolved Expendable Launch Vehicle flight
  • The 13th National Reconnaissance Office use of Atlas 5
  • The 109th United Launch Alliance flight overall
  • The 56th Atlas 5 under United Launch Alliance
  • The 23rd NRO launch by United Launch Alliance
  • The 78th United Launch Alliance flight from Cape Canaveral
  • The 43rd 400-series flight of the Atlas 5
  • The 6th Atlas 5 to fly in the 421 configuration
  • The 45th NRO launch since acknowledging flights in 1996
  • The 22nd NRO launch from the Cape Caneraval
  • The 3rd NRO launch this year

European Space Agency plans to clean the Space Debris

The European Space Agency ESA is planning a specialized capture mechanism to remove the space junk and pull down the abandoned satellites to burn up in atmosphere.

The e DeOrbit Mission, which is the ESA's Clean Space initiative, is designed to capture an ESA owned satellite which is now in low earth orbit around the Earth but not working at present.  If every thing goes well, the capture mechanism - like a robotic arm, net or a harpoon -  will latch on to the target in the year 2023 and bring it back to a place where it can safely burn up in Earth's atmosphere.  


But we do not know whether this kind of plan works or not  and it is not an easy task.  There are several challenges that ESA scientists have to face.   They have to identify the fast moving target, find a safe and secure way to chase it down and capture it and synchronize the orbital paths with the satellite to bring it down into our Atmosphere in a controlled manner. . 
Even though the concept is straight forward, the implementation may be difflcult  -  a De Orbit will be like nothing ESA has ever attempted before.  The chaser satellite needs extremely sophisticated guidance, navigation and control to synchronize the motion of the target and then capture it.  

For more details please visit :  http://www.space.com/33414-space-junk-cleaning-satellite-mission-2023.html





Sunday, July 10, 2016

India's PSLV-C34 blasts off with 20 satellites

In its 36th flight (PSLV-C34), the ISRO's Polar Satellite Launch Vehicle lifted off early Wednesday ( 22nd June, 2016 ) with an assortment of payloads for Indian Government, domestic universities, and institutions and companies from Indonesia, Canada, Germany and United States including a pathfinder satellite for Google's Terra Bella Earth observation mission.



The PSLV-C34 successfully launched the 727.5 Kg Cartosat-2 series satellites along with 19 other co-passengers on 22nd June, 2016 at 09:26 hrs IST. This is the 35th consecutive successful flight of PSLV and 14th in its 'XL' configuration.  The total weight of all the satellites was 1288 Kgs. The launch occured at 03:56 GMT on Wednesday.. 

The 44 meter tall rocket, boosted by its six strap-on motors climbed into a clear sky, initially veering south east from the launch base, then turning south once over the bay of Bengal.  The unusual trajectory, called a 'dogleg' maneuver, was required to avoid flying over Sri Lanka. 

Four of the strap-on motors were ignited at lift off, then the last pair fired at T+25 seconds moments later the PSLV accelerated faster than speed of sound. 

The first four strap-on motors were separated at T+70 seconds, followed by separation of other pair at T+92 seconds as the PSLV soars at an altitude of 47 Kilometers.  

The first stage motor burned out and separated at T+109 seconds and a fraction of a second later, the second stage's liquid fueled Vikas Engine turned on with a puff of exhaust visible to ground based cameras.  

The Vikas engine produced 180,000 pounds of thrust and burned 42 tons of Hydrazine and nitrogen tetroxide propellants during two-and-half minutes of operation.  The heat shield or the payload fairing, fell down into two halves at T+155 seconds to reveal the 20 satellites packaged on top of the rocket..

The third stage solid motor ignited at T+4 minutes 22 seconds, at an altitude of 217 Kms.  Finally a twin-engine liquid-fueled fourth stage assumed control of the mission at T+8 minutes 17 seconds for an eight minutes firing to reach the proper speed to enter the targeted polar orbit.

Here is a video of the PSLV-C34 Launch...











India’s Reusable Launch Vehicle-Technology Demonstrator (RLV-TD), Successfully Flight Tested

On 23rd May, 2016,  ISRO successfully flight tested the India's first winged body aerospace vehicle operating in hyperosonic flight regime.

In this experimental mission,  the HS9 solid rocket booster carrying the RLV-TD lifted off from the First Launch Pad at Satish Dhawan Space Center, Sriharikota at 07:00 hrs IST on 23rd May, 2016.  After successful flight of 91.1 seconds, the HS9 was burnt out following which both HS9 and RLV-TD mounted on its top coasted to a height of about 56 Kms.  At this height, the RLV-TD separated from HS9 booster and further ascended to a height of about 65 Km.



From the height of 65 Kms, the RLV-TD started its descent followed by atmospheric re-entry at around Mach 5 ( five times speed of sound ).  The navigation, guidance and control system of the vehicle steered it during this phase for safe descent.  After successfully surviving the high temperatures of re-entry with help of thermal protection system, the RLV-TD successfully landed at the defined landing spot over Bay of Bengal which is at a distance of 450 Km from Sriharikota.  The total flight duration from launch to landing lasted for about 770 seconds.

Some of the critical technologies like autonomous navigation, guidance and control, reusable thermal protection system and re-entry mission management were successfully validated.  

The final version of RLV would take about 10 to 15 years to get ready.

Here is a video of the RLV TD launch...




India launches 7th navigation satellite onboard PSLV-C33

In the 35th flight of PSLV ( PSLV-C33) of ISRO has launched the 1425 Kg IRNSS-1G, the 7th satellite in the Indian Regional Navigation Satellite System (IRNSS) on 28th April, 2016 from Satish Dhawan Space Center, Sriharikota.  This is the 34th consecutive successful mission of PSLV and the 13th in its 'XL' configuration. 

Honourable Prime Minister of India, Sri Narendra Modi congratulated all the ISRO scientists and the team ISRO for completing the IRNSS constellation and dedicated the IRNSS system to the nation and named it as "NavIC" ( Navigation Indian constellation ).

The PSLV-C33 lifted off at 12:50 Pm IST from the first launch pad with the ignition of first stage, the subsequent flight events took place as planned.  After 19 minutes and 42 seconds, the IRNSS-1G spacecraft was injected into the elliptical orbit of 283 Km x 20718 Km inclined at an angle of 17.867 degrees to the equator.

After separation, the solar panels of the IRNSS-1G were deployed automatically and ISRO's Master Control Facility at Hasan took over the control of the spacecraft.  The orbital manoeuvres were conducted by MCF and the satellite was finally placed into Geo stationary orbit at 129.5 degrees East longitude.

IRNSS-1G is the seventh and the last satellite in the IRNSS constellation.  Here is a video of the PLSV-C33 Launch..




India launches 6th Navigation satellite onboard PSLV-C32

India has launched the 1425 Kg IRNSS-1F, the sixth satellite in the Indian Regional Navigation Satellite System ( IRNSS) on 10th March, 2016 afternoon.  This is the 34th flight of PSLV launch vehicle. The launch took place from India's space port, Sriharikota.   This is the 12th PSLV flight in its 'XL' configuration. 



After the lift off at 16:01 IST from Second launch pad with the ignition of first stage, the subsequent important flight events took place as planned.   The IRNSS-1F satellite was injected to an elliptical orbit of 284 Km x 20719 Km inclined at an angle of 17.866 degrees to the equator after 19 minutes 14 seconds.  The solar panels of the spacecraft were deployed automatically after separation.  ISRO's Master Control Facility at Hasan took over the control of the satellite and placed the satellite into a Geostationary orbit at 32.5 degree East longitude.  This is the 6th of the seven satellites constituting the space segment of Indian Regional Navigation Satellite system.  IRNSS-1A, 1B, 1C, 1D and 1E were the first five satellites of the constellation were successfully launched by PSLV on July 02, 2013,  April 04, 2014, October 16, 2014, March 28, 2015 and January 20, 2016 respectively. 

The IRNSS is an independent regional navigation system designed to provide position information in the Indian region and 1500 Km around the Indian main land.  The IRNSS would provide two types of services namely, Standard positioning services (SPS)- provided to all users and Restricted Services ( RS )  provided to authorized users.  

There are a number of ground stations responsible for the generation and transmission of navigation parameters, satellite ranging and monitoring etc.  18 stations have been established across the country.  

Here is a video of the PSLV-C32 LAUNCH...