PSLV-C40/Cartosat-2 Series Satellite Mission: Jan 12, 2018

[KapitaanAli]

I am sure ISRO knows better, but I thought a gap of about 2-3 seconds between each satellite ejection, would have all but ensured that there would be no collision between them. I suspect such a spacing would also ensure more economic burning of their internal fuels used up for the evasive maneuver that they most likely carry out immediately after their ejection.

Just my 2 cents, anyway.

This is one of the factors that make multiple injections difficult. This will give you a new appreciation of ISRO putting 104 satellites together in orbit. This is why the "haha most were nanosatellites" argument is nonsense and why the CIA said that it's alarming.

When there are multiple satellites, each are injected after reorienting the final stage so that they're in close but separate orbits. Separation velocities and launch sequence are carefully chosen.

This is not as simple as it sounds. Calculations must be done for the entire lifetime of the satellites. In fact this is the reason behind the reorientation and a proper time interval. Indirectly, this will also avoid collision at the time of injection.

But calculations aren't limited to this.
Even the possible plume interactions from the final stage and reaction control thrusters must be studied.
Another factor to consider are the possible dispersion in the separation system parameters. We've to analyse what the position of each satellite/stage are at different times in the future. This relative distance changes in time as shown:

 

[kadamba-warrior]

This is one of the factors that make multiple injections difficult. This will give you a new appreciation of ISRO putting 104 satellites together in orbit. This is why the "haha most were nanosatellites" argument is nonsense and why the CIA said that it's alarming.

When there are multiple satellites, each are injected after reorienting the final stage so that they're in close but separate orbits. Separation velocities and launch sequence are carefully chosen.

This is not as simple as it sounds. Calculations must be done for the entire lifetime of the satellites. In fact this is the reason behind the reorientation and a proper time interval. Indirectly, this will also avoid collision at the time of injection.

View attachment 448081

But calculations aren't limited to this.
Even the possible plume interactions from the final stage and reaction control thrusters must be studied.
Another factor to consider are the possible dispersion in the separation system parameters. We've to analyse what the position of each satellite/stage are at different times in the future. This relative distance changes in time as shown:
View attachment 448082

I have no illusions about the complexity involved and like I said, ISRO knows better. I also know in a limited way how satellites reorient themselves after deployment in an initial parking orbit that include both static (using solar panels for drag over course of months) and dynamic methods that use rocket fuel.

But I was thinking if spacing the deployment with several seconds in between (instead of spacing of fraction of a second) would be more practical and if so, may result into faster reorientation since the satellites need not worry about collision as much as they need to do now.

BTW, I also saw another video of ISS deploying 2 nanosatellites while the astronauts were watching from their windows and the spacing between those2 satellites was even smaller. The satellites were practically touching each other when they were ejected out of their slots. So ISRO is already doing something better than others.

 

[KapitaanAli]

I have no illusions about the complexity involved and like I said, ISRO knows better. I also know in a limited way how satellites reorient themselves after deployment in an initial parking orbit that include both static (using solar panels for drag over course of months) and dynamic methods that use rocket fuel.

But I was thinking if spacing the deployment with several seconds in between (instead of spacing of fraction of a second) would be more practical and if so, may result into faster reorientation since the satellites need not worry about collision as much as they need to do now.

BTW, I also saw another video of ISS deploying 2 nanosatellites while the astronauts were watching from their windows and the spacing between those2 satellites was even smaller. The satellites were practically touching each other when they were ejected out of their slots. So ISRO is already doing something better than others.

Parking orbit is a different concept and applied when we go to geostationary or lunar or interplanetary orbits. We go to temporary orbit and then go to another. Not the case here.

Also, this reorientation is done by the final stage of the rocket, not the satellites. So there's no question of collision at the time of injection. Satellites don't need time.

 

[kadamba-warrior]

Parking orbit is a different concept and applied when we go to geostationary or lunar or interplanetary orbits. We go to temporary orbit and then go to another. Not the case here.

Also, this reorientation is done by the final stage of the rocket, not the satellites. So there's no question of collision at the time of injection. Satellites don't need time.

Perhaps, my usage of the term "Parking" orbit may not be entirely accurate here, but I am only referring to the temporary physical location of the spacecraft immediately after it is ejected out by the launch vehicle before it's final place of deployment. I am fully aware that an interplanetary mission is different than a simple earth orbiting satellite. No need to mix the two.

Not sure of the point of the debate here, but even as a noob I can tell you that reorientation has to be done by each individual satellite - especially when you don't have a dedicated launch vehicle for any one particular satellite.

BTW, the reorientation I am referring to is only the deployment of the satellite such as to allow maximum solar exposure, best antennae/camera/sensory alignment that is effected by the reaction wheels using it's Star Sensor for reference.

As you can see below, reorientation is something that an individual satellite has to do on it's own since there is no way the launch vehicle can reorient a whole flock of satellites that essentially tumble out of the launch vehicle spinning "seemingly" haphazardly.

 

[#hydra#]

Primitive?
Right now ISRO is top 3 Space agencies in the world, even ahead of China.
Wonder which brain fade can one have to use the word primitive.

No man,we are behind Chinese. I will keep both China and European space agency in third place,and Japanese in 4th.

 

[KapitaanAli]

Jan 16, 2018
First Day Image from Cartosat-2 Series Satellite

 

[The_magnificent]

Image is very sharp and clear

 

[#hydra#]

Image is very sharp and clear

I do believe that it's not the best resolution,they won't release the full resolution pic to the pic I guess.

 

[egodoc222]

I do believe that it's not the best resolution,they won't release the full resolution pic to the pic I guess.

No...this is not the full resolution...they are not released for the public!!

 

[KapitaanAli]

Jan 23, 2018
Images from INS-1C and Microsat


Images from INS-1C

Imaging targeted over India for maximum Land coverage.

Image from Microsat

Microsat Image of Porbander

INS-1C
Indian Nano Satellite-1C (INS-1C) is another Indian co-passenger payload of PSLV-C40. It is the third satellite in the Indian Nano satellite series. The first two satellites of this series were carried as co-passenger payloads by PSLV-C37 in February 2017. INS-1C carries Miniature Multispectral Technology Demonstration (MMX-TD) Payload from Space Applications Centre (SAC). Data sent by this camera is useful for topographical mapping, vegetation monitoring, aerosol scattering studies and cloud studies.

Microsat

PSLV-C40 carries a Microsatellite (Microsat) built by ISRO as a co-passenger payload. Microsat is a small satellite in the 100 kg class that derives its heritage from IMS-1 bus. This is a technology demonstrator and the fore runner for future satellites of this series. The satellite bus is modular in design and can be fabricated and tested independently of payload.

 

[KapitaanAli]

Indigenously Developed Metal-based Origami Payload tested in INS-1C
Indian Nano Satellite-1C (INS-1C) is an experimental satellite launched by PSLV-C40 on Jan 12, 2018 as a co-passenger payload. It is the third satellite in the Indian Nano Satellite (INS) series. The first two satellites (INS-1A and INS-1B) of this series were carried as co-passenger payloads by PSLV-C37 in February 2017. INS-1C carries Miniature Multi-spectral Technology Demonstration (MMX-TD) Payload from Space Applications Centre (SAC), ISRO Ahmedabad.

Compact imaging systems with reduced weight and size offer tremendous opportunities for their use in space borne micro/nano satellites and planetary missions where size and weight are at a premium. Although miniature cameras such as those found in cell-phones are now available commonly, their resolution and light collection are poor with respect to their full size counterparts. Robust Technology Development Programme of SAC/ISRO developed an innovative satellite payload using the concept of Origami - the art of folding paper. ISRO Nano Satellite (INS-1C) payload team has used the concept of multi-fold reflective optics to design imagers of significantly reduced thickness compared with conventional refractive cameras.

This multi-fold optical configuration is known as Origami optics. It is important to note that the reflective optics is based on metal mirrors, rather than the usual glass based Origami lens. The use of metal reflectors makes the camera potentially much more versatile in terms of spectral coverage. The mirrors and the optical assembly were developed indigenously. The optics is fabricated using single-point diamond turning machine with a fast-tool servo. Ray diagram of the Origami optics, Individual mirrors and Comparison with a conventional lens system are shown in the figures below:

Optical Ray Diagram

Mirror-1 Mirror-2

Indigenously developed Metal Origami Optics

Comparison between Origami Optics and Conventional Lens

Utilising the capability of the optics, a compact Miniature Multi-spectral Technology Demonstration (MMX-TD) payload was configured for INS-1C nanosatellite. The camera provides RGB snaps of 29 km x 29 km area with 23 m ground sampling from polar sun-synchronous orbit of 505 km altitude.

The first payload operation was carried out successfully on January 16, 2018 and since then, the payload is providing excellent images. Data sent by this camera is useful for topographical mapping, vegetation monitoring, aerosol scattering studies and cloud studies etc.,.

INS-1C MMX-TD Payload Mounted on Spacecraft

Images acquired by MMX-TD Payload

Himalyan Region seen from INS -1C

Nagqu, Tibet