Zombie Sat May Soon Be Back In Business

Paris And Washington — Intelsal thinks there is a good chance it will regain use of Galaxy 15, the wayward “Zombie Sat” that terrorized telecom satellite neighborhoods around the globe until it was brought under control late last month.

Galaxy 15 currently has its payload turned off. It is expected to arrive at 93 deg. W. Long. on Jan. 15 for a complete checkout, including validation of three command & control software patches uploaded in December to ensure the incident will not recur, company officials say.

According to tests run so far, the C-band payload and FAA’s Wide Area Augmentation System L-band transponder — whose loss has reduced redundancy for air navigation in the U.S. to dangerously low levels — is fully operational, though testing of the transponder continues.

Working Order

All major subsystems except command & control, including thermal and power management, attitude control, pointing beacons and ranging, are also in normal working order. The bus, subsystems, payload, antenna, battery and command & control fixes all will undergo extensive testing during checkout to compare results with original Galaxy 15 in-orbit test data and ensure they are operating nominally.

If it receives a clean bill of health, the spacecraft could be available for in-orbit backup services as early as Jan. 31 as it begins its drift to 129/133 deg., Toby Nassif, Intelsat’s vice president for satellite operations and engineering, told reporters Jan. 13.

Engineers are focusing on firmware in the baseband equipment (BBE) command unit — since corrected by the software patches — as the source of the incident, and they hope further testing will enable them to narrow down and complete the failure review board inquiry initiated under the control of Orbital Sciences Corp., which built the spacecraft. Orbital also has uploaded the software patches, which were validated in orbit in October, on other Intelsat spacecraft that use the Star 2 bus employed in Galaxy 15.

Upgrades

Enhancements include a modified emergency command channel, using a fully independent communications path, which permits the spacecraft to be commanded if the BBE command malfunctions; a patch that turns off the payload automatically if no command is received for 21 days; and a patch to reset the BBE if no command is received for 14 days.

The root cause of the incident, which occurred on April 5, 2010, has yet to be determined. However, the 120 potential causes initially identified have been reduced to two, Intelsat says. Solar flares, the long rumored culprit, are not among them. Orbital expects to submit a final failure review report in mid-February.

Thanks to an ingenious team effort orchestrated by Intelsat, other operators and affected customers, the loss of control of Galaxy 15 did not lead to substantial interference or loss of service despite 15 flybys over six months, Intelsat and other operators note. Moreover, the experience gained will stand the industry in good stead should any similar incident occur in the future.

Intelsat officials say the company does not expect to make a material charge to its profit and loss account as a result of the recovery effort, despite warnings in the third quarter that it might have to do so. However, it was forced to take a $104 million second quarter write-down for the satellite.