Why India is building a spaceport 640 kilometers south of its first

India’s only orbital spaceport stands on Sriharikota, a barrier island on the east coast at about 13.7 degrees north. The location has served the country well. Yet ISRO is now building a second site at Kulasekarapattinam in Tamil Nadu, some 640 kilometers to the south, dedicated to small rockets. Its chairman, V. Narayanan, said this month that the first launch from there is likely in March or April 2027.

It looks odd at first: why build a whole new spaceport a few hundred kilometers down the same coast? The answer lies in where each kind of orbit sends a rocket, and in what is on the map directly south of Sriharikota.

What Sriharikota is good at

Earth’s rotation gives every rocket a free start. At the equator the ground moves east at about 465 meters per second, and that speed shrinks with the cosine of latitude. A rocket heading east keeps it. We calculated what that is worth at four well-known sites:

Latitude matters even more on the way to geostationary orbit. A satellite launched due east starts out tilted at an angle equal to the latitude of its pad, and that tilt has to be removed high up, using its own fuel. In a simplified case where the whole correction happens at the top of the transfer orbit, the final maneuver costs about 1,493 meters per second from Kourou, 1,571 from Sriharikota, 1,838 from Cape Canaveral and 2,274 from Baikonur. Those are idealized minimums, since real trajectories are shaped by range safety and steering limits, but the order holds. For eastward flight, Sriharikota sits close to the best of the world’s major sites.

The trouble with going south

Polar and sun-synchronous orbits, which most Earth-observation satellites use, require a rocket to head almost directly south. A typical sun-synchronous orbit near 500 kilometers has an inclination of about 97.4 degrees. From Sriharikota, we calculate that this needs a heading of about 187.6 degrees, slightly west of due south.

Draw that line on a map and you can see the problem. By the latitude of northern Sri Lanka, near 9.8 degrees north, it has reached about 79.7 degrees east, right off the Jaffna peninsula. Further down, at the latitude of Colombo, it runs only about 60 kilometers offshore. This is a simplification, since the Earth turns beneath the rocket as it climbs, but it shows the shape of the difficulty. A rocket sheds spent stages along its path, and a failed one comes down somewhere along it. That is why such a corridor is not acceptable.

ISRO’s answer has been to launch east over the Bay of Bengal and then bend the trajectory south, around Sri Lanka. Engineers call this a dogleg, and it works. PSLV has flown polar missions this way for decades.

What the dogleg costs

Turning a rocket in flight costs speed that would otherwise go toward reaching orbit. For a sense of the scale, changing the plane of a spacecraft already moving at orbital speed by just 5 degrees takes about 660 meters per second. A real dogleg costs less than that, because the rocket turns while it is still moving slowly and climbing. We could not find a published figure for the penalty on individual Indian missions, so we will not offer one. The direction of the effect is not in doubt, though.

You will often read that large rockets barely notice the detour. That is too generous. A velocity penalty takes a comparable share of performance from any rocket. What differs is how much room the rocket has to spare. ISRO rates the PSLV at up to 1,750 kilograms to sun-synchronous polar orbit. The SSLV, its small launcher, is rated for up to 500 kilograms to a 500-kilometer planar orbit, and a polar orbit is harder because the rocket gets none of the rotational boost described above. On a vehicle that size, a detour eats directly into a payload that was already modest.

What the new site changes

Kulasekarapattinam lies at about 8.4 degrees north and 78 degrees east, on the Indian mainland and well to the west of Sri Lanka. The same 187.5-degree heading from there passes near 77.9 degrees east at the latitude of Colombo, roughly 220 kilometers west of the city, and continues over open ocean. A small rocket can fly its polar trajectory without the bend.

There is a second, simpler reason. Sriharikota handles India’s orbital launches, and the government has said SSLV launches, along with those of similar rockets from private companies, will move to the new site once it is commissioned. Pad availability matters when a country wants to launch small satellites often.

Where the project stands

In December 2025 the government told Parliament that commissioning was targeted for the 2026–27 financial year, with Rs 985.96 crore allocated and Rs 389.58 crore spent by 31 July 2025. An earlier goal was a first launch by December 2026. Narayanan’s latest statements put it at March or April next year, and he has said the Tamil Nadu government has handed over almost 2,300 acres for the site.

Treat that date as a target. Spaceport schedules tend to slip, and this one already has. The geometry, however, will not change. Like the arithmetic that keeps Voyager talking to Earth, it is the kind of constraint engineers can design around but never remove.

How we worked this out

The rotation speeds use 465.1 m/s at the equator and the site latitude. The geostationary figures assume a transfer orbit whose inclination equals the site latitude, with speeds of 1,596 m/s at apogee and 3,075 m/s in the final orbit. The headings come from the standard relation between launch azimuth, latitude and inclination, and the ground tracks are straight-line sketches. None of these replace a real trajectory simulation, and we have labeled them accordingly.

Sources

• Deccan Chronicle: First rocket launch from Kulasekarapattinam likely next March–April
• ThePrint (PTI): Rocket launches from the spaceport will commence next year
• Swarajya: Kulasekarapattinam targeted for commissioning in FY27, Centre tells Parliament
• ISRO: Polar Satellite Launch Vehicle
• ISRO: Small Satellite Launch Vehicle
• Wikipedia: Dogleg maneuver