Concerns about LEO Risks: D.K. Sachdev, SpaceTel Consultancy 
By Paul Dykewicz 

D.K. Sachdev is one of the most accomplished engineers in the industry and, as a result, his views gain attention. One of his concerns is an increasing amount of space debris that boosts the risks to spacecraft that operate in low-Earth-orbit (LEO). (Read more on low-earth-orbit threat).

Such concerns proved warranted on February. 10, 2009, when a collision in LEO between an operational Iridium communications satellite and the retired Cosmos 2251 communications satellite sent pieces of both spacecraft spewing outward. Experts described the accident as the first known incident in which two fully intact spacecraft collided. Sachdev expressed concern that the risks in LEO are growing and that shielding techniques to protect spacecraft from small debris would not prevent a similar mishap in the future.

A much larger number of space debris in LEO makes that orbit significantly more dangerous than geosynchronous orbit (GEO), which is 36,000 kilometers above the Earth. Although improved shielding is one way to protect spacecraft, the technique has its limitations.

Questions exist about the effectiveness of shielding techniques, and whether the risk-mitigation effort adds significantly to the weight of a satellite and the cost of building and launching it.

“In qualitative terms, the impact will be larger in LEO for two reasons: there is more debris and spacecraft are generally smaller than at GEO,” Sachdev said. 

Therefore, the extra mass of any shielding employed, as a percentage of spacecraft mass, is greater for spacecraft that will operate in LEO than for those in GEO.

“For GEO spacecraft, their transit time through areas of highest debris is very brief and the spacecraft are not fully deployed or opened up yet,” Sachdev said. “At GEO, the main concern is to protect sensitive hardware from micro-meteorites. This is achieved mainly through proper placement of such hardware within the spacecraft.”

As a result, the “mass impact” in GEO is minimal, Sachdev said.

Before becoming the founder and president of Vienna, Va.-based SpaceTel Consultancy, Sachdev held a variety of engineering posts. In his native India, he had several senior positions at the Indian Telecommunications Service and in industry for 22 years. His last assignment was as general manager at ITI Ltd., where he was responsible for the development of a large range of telecommunication systems that included equipment for India’s second Intelsat Standard A earth station.

Upon moving to the United States, Sachdev held key engineering positions at Intelsat between 1978 and 1996. He started managing research and development when he first arrived at the satellite organization and later led system planning and several engineering functions there. His top accomplishments at Intelsat included leading the planning and engineering of two major spacecraft programs: Intelsat VII/VII and Intelsat VIII.

While at Intelsat, the organization established a track record for uncommonly high reliability with its in-orbit spacecraft. 

“In the period I was there, a good part of the reliability came from that of earth stations that were maintained by user companies in different countries,” Sachdev said. “Intelsat‘s main focus was on the high level of training for the Satellite Control Center staff.”

Sachdev’s group was responsible for the planning and the engineering of satellites. To that end, his team established procurement and specification practices that have since become “industry standards,” he explained.

“These practices encouraged more rigorous qualification methods during design phases and during full spacecraft testing,” Sachdev said. “These can claim some share of the high system reliability.”

Sachdev later led the engineering, deployment and operations of the world’s first digital radio system when he was senior vice president of engineering and operations at WorldSpace between 1996 and 2000. He also helped to develop the system architecture, spacecraft and terrestrial repeater system for XM Satellite Radio.

In recent years, Sachdev became an adjunct faculty member at George Mason University, where he teaches a graduate-level course in system engineering for telecommunications systems.

In recognition of his lifetime professional achievements, he received the Vikram Sarabhai Award in 1976, the Arthur C. Clarke Innovator’s Award in 2003 and was inducted into the Society of Satellite Professionals International Hall of Fame in 2009. He has also authored two books about satellite systems.

Paul Dykewicz is a seasoned journalist who has covered the development of satellite television, satellite radio, satellite broadband and hosted payloads.