India's new rocket fails to put satellites in right orbit in debut launch

India's new rocket launched for the first time on Saturday night (Aug. 6) but failed to deliver its satellite payloads into their intended orbit due to a sensor issue.

The 112-foot-tall (34 meters) Small Satellite Launch Vehicle (SSLV) lifted off from Satish Dhawan Space Centre on India's southeastern coast on Saturday at 11:48 p.m. EDT (0348 GMT and 9:18 a.m. India Standard Time on Sunday, Aug. 7) with two satellites onboard.

The rocket's three solid-fueled stages performed well, but its fourth and final stage, a liquid-fueled "velocity trimming module" (VTM), hit a snag: Indian Space Research Organisation (ISRO) officials reported a loss of data from the rocket and, just over five hours after liftoff, ISRO announced the mission had failed.

"The entire vehicle performance was very good" at the start, but ultimately left the two satellites in the wrong orbit, ISRO Chairman S. Somanath said in a video statement after the launch. "The satellites were placed in an elliptical orbit in place of a circular orbit."

Related: ISRO: The Indian Space Research Organisation

Instead of placing the satellites in a circular orbit 221 miles (356 kilometers) above Earth, the rocket left them in an orbit that ranged from 221 miles to as close as 47 miles (76 km). That orbit was not stable, and the satellites have "already come down, and they are not usable," Somanath said.

ISRO officials said on Twitter that a sensor failure that was not detected in time to switch to a "salvage action" caused the orbit issue. An investigation into the failure is planned. 

"What we are going to do now is to identify this specific problem and why this isolation happened and why it went into an unacceptable orbit," Somanath said. ISRO will use that investigation to correct issues for a second test flight of the SSLV rocket, he added. 

"But for that problem, we couldn't see any other anomalies," he added. "Every other new element that has been incorporated in this rocket performed very well."

The main payload on Saturday's test mission was EOS-02, a 300-pound (135 kilograms) experimental Earth-observation satellite. "This microsat series satellite offers advanced optical remote sensing operating in infrared band with high spatial resolution," ISRO officials wrote in a description of Saturday's mission.

The second satellite that went up Saturday was an 18-pound (8 kg) cubesat called AzaadiSAT. This little spacecraft was loaded with 75 different payloads, which were built by female students across India to perform a variety of "femto-experiments." 

"The payloads include a UHF-VHF transponder working in ham radio frequency to enable voice and data transmission for amateur radio operators, a solid state PIN diode-based radiation counter to measure the ionizing radiation in its orbit, a long-range transponder and a selfie camera," ISRO officials wrote in the mission description.

As its name indicates, the SSLV is designed to launch relatively small satellites; the rocket can loft up to 1,100 pounds (500 kg) to low Earth orbit (LEO), according to ISRO officials.

When the SSLV comes fully online, India will have three rockets in its current fleet. The two others are the 144-foot-tall (44 m) Polar Satellite Launch Vehicle (PSLV), which can haul up to 3,860 pounds (1,750 kg) to a sun-synchronous polar orbit, and the Geosynchronous Satellite Launch Vehicle (GSLV), which can take 11,000 pounds (5,000 kg) to LEO or 5,500 pounds (2,500 kg) to the much higher geostationary transfer orbit.

Editor's note: This story was updated at 9:45 a.m. EDT (1345 GMT) with new details of the launch failure from ISRO and its Chairman S. Somanath.

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or on Facebook.