Editorial Today – Reusable launch vehicle

Issue ISRO (Indian Space Research Organisation) has successfully launched a Reusable Launch Vehicle (RLV).

What is a Launch Vehicle? It is a carrier to take satellites into the space.

What is reusable launch vehicle? It as vehicle which can be used for multiple launches.

What is TSTO Two-stage-to-orbit.

How many countries have tested vehicles that are similar or resemble the space shuttle? US, Japan, France and Russia.

Advantages of Reusable Launch Vehicle Cost saving and space debris.

What the test was all about What was tested is only a prototype.

How much time did it take to reach this stage of having a winged spacecraft? It took about 10 years to develop the model.

What were the new materials needed to develop this flight model?

Carbon-carbon composite and heat-resistant silica tiles.

Is the underbelly coated with special tiles? Thermal protection tiles have been put on the entire belly region.

How much payload can it carry to space? 10-15 tonnes.

 

Issue

• ISRO (Indian Space Research Organisation) has successfully launched a Reusable Launch Vehicle (RLV) called the Reusable Launch Vehicle ( RLV-TD) space shuttle, the first ever for the country.
• The ‘dummy’ RLV was launched from Sriharikota in Andhra Pradesh into the orbit around Earth, and then glided back onto a virtual runway in the Bay of Bengal, some 500 kilometers from the coast.
• This is the first time ISRO launched a winged flight vehicle.

 

What is a Launch Vehicle?

• A satellite launch vehicle as the name suggest is a carrier to take satellites into the space. It is the rocket that we see in our television screen going up. The satellite is inside the rocket, rocket takes it into space puts them into the orbit.
• India currently uses two kinds of launch vehicle PSLV (Polar Satellite Launch Vehicle) and GSLV (GeoSynchronous Satellite Launch Vehicle).

 

What is reusable launch vehicle?

• Rocket takes satellite into space, puts them into the orbit and it itself becomes useless. The space agency loses its rockets and the rocket itself adds to space debris.
• Reusable launch vehicle is a new technology to tackle this problem. What ISRO is trying to do is to have this vehicle take the satellite into space, leave it there and then come back to earth to be used for future launches.

 

What is TSTO

• A two-stage-to-orbit (TSTO or DSTO – Double/Dual-Stage-To-Orbit) launch vehicle is a spacecraft in which two distinct stages provide propulsion consecutively in order to achieve orbital velocity. It is intermediate between a three-stage-to-orbit launcher and a hypothetical single-stage-to-orbit (SSTO) launcher.
• At liftoff the first stage is responsible for accelerating the vehicle. At some point the second stage detaches from the first stage and continues to orbit under its own power.
• An advantage of such a system over single-stage-to-orbit is that the entire mass of the spacecraft is not carried into orbit. This reduces the cost involved in reaching orbital velocity as much of the structure and engine mass is ejected and a larger percentage of the orbited mass is payload mass.

 

 

How many countries have tested vehicles that are similar or resemble the space shuttle?

•  Already, four countries have done this, the US, Japan, France and Russia. They have tested this type of vehicle. The US retired its space shuttles in 2011 and Russia flew once long ago.

 

Advantages of Reusable Launch Vehicle

• 80 per cent of the costs of launch vehicles consist of physical structure and the technology inside. Only 20 per cent is on fuel and other expendables (Average cost of constructing PSLV is 120 crore and GSLV is 170 crore)
• Instead of this if a reusable technology is used, theoretically somewhere around 80 per cent of this cost is saved.
• By coming back it is not adding to space debris.

 

What the test was all about

• What was tested is only a prototype , a small version of what it actually will be. There is lots of development which still needs to be done over the next 8-10 years before it becomes develop into an operational launch vehicle.
• The idea is to have this structure or design of a reusable vehicle posted on a pslv or gslv so that they can become a reusable launch vehicle.
• The ultimate aim is to have space vehicle take the shape of aeroplane wherein they can take off from run way , do what they have to do it in space and then come back for further flights in future.
• Many more such successful launches have to be undertaken before the RLV becomes a reusable launch system to put satellites into orbit.
• Some of the objectives of this launch were to test the aero-thermodynamic characterisation of the vehicle with wings when it re-enters the atmosphere at hypersonic speed; the control and guidance system; the control system to land the vehicle at a specific location; and the hot structure, the basic body-carrying part of the vehicle with heat protecting tiles.
• The ultimate objective is to test the vehicle’s performance when it travels at a speed of Mach 25 using air-breathing propulsion. It will take 10 to 15 years, and several more launches, before ISRO readies a reusable launch vehicle for commercial use.
• No other space agency has reusable launch vehicles in operation, and ISRO has taken a lead in developing one.
• Learning from the mistakes of the U.S. National Aeronautics and Space Administration (NASA) in its space shuttle programme, ISRO will not use the same reusable vehicle to launch satellites and carry astronauts as it drastically reduces the payload capacity and thereby increases the cost per kg.
• ISRO will also use cutting-edge technology to shield the launch vehicle from intense heat to reduce, if not completely eliminate, refurbishment expenses. Getting this right would enable the vehicle to be reused within a very short span of time.
• The test-launch is considered a significant step in India’s space endeavour. It’s especially important, because in 2011, the US’s NASA abandoned its reusable space shuttle project.

 

 

How much time did it take to reach this stage of having a winged spacecraft?

• It took about 10 years to develop the model.
• It needed to do a lot of technological development, like materials development, thermal protection system development, propulsion system development.
• Most importantly, the configuration of a reusable launch vehicle is crucial. Because this particular vehicle is going to operate in a very wide Mach range from 25 to zero, so having a single configuration meeting all the requirements is very difficult. Therefore, defining a configuration for a hypersonic wave flight, and its validation and how it is to be maneuvered to bring to a defined point is a challenge and the key objective of this mission.

 

What were the new materials needed to develop this flight model?

• One particular material is called carbon-carbon composite, a special heat resistant material. This is used because during re-entry, the vehicle faces the friction of atmosphere — the first portion that is going to face a severe thermal environment of around 750 degree Kelvin will be the nose cone. Internally, it will become hot because this material faces the atmosphere. Therefore, the high temperature from outside will not be passed on inside.
• The other is heat-resistant silica tiles, a very light material that is rainproof.

 

Is the underbelly coated with special tiles?

•  Basically, when the vehicle enters the atmosphere, it will have a high angle-of-attack. It is the belly area that faces the atmosphere; hence, this area should be protected. That is why thermal protection tiles have been put on the entire belly region. The outside temperature would be 750 degrees Kelvin but the inside will still be cool.

 

How much payload can it carry to space?

• The ultimate reusable launch vehicle should be able to carry something like 10-15 tonnes into the low earth orbit.