PARIS — Satellite fleet operator AsiaSat said June 22 it had booked a launch aboard an International Launch Services (ILS) Proton rocket in a $107 million contract that protects AsiaSat against possible delays at launch-services provider Space Exploration Technologies Corp. (SpaceX).

Under the ILS contract, AsiaSat will make a down payment of $10.3 million by July 5 to preserve the right to a March-to-May 2014 slot aboard an ILS Proton for either the AsiaSat 6 or AsiaSat 8 satellite. Both are under construction by Space Systems/Loral of Palo Alto, Calif.

The total price for the launch of either satellite is $107 million, AsiaSat said in a June 22 submission to the Hong Kong Stock Exchange.

AsiaSat in February signed with Hawthorne, Calif.-based SpaceX for the launch of the two satellites on separate Falcon 9 rockets. Under that contract, AsiaSat agreed to pay $52.2 million per satellite — half the ILS price.

But the SpaceX contract stipulated that the AsiaSat 6 contract will be canceled, and all advance payments refunded, if the launch does not occur by March 31, 2014. For AsiaSat 8, the launch deadline is May 31, 2014.

AsiaSat has entered into a partnership with fleet operator Thaicom of Thailand that gives the two operators joint use of AsiaSat 6, which Thaicom calls Thaicom 7. The partnership enabled Thailand and Thaicom to retain access to the 120 degrees east orbital slot, assuming the launch occurs on time.

SpaceX is modifying its Falcon 9 rocket with a new engine, a larger propellant tank and a wider payload fairing to compete for the launch of telecommunications satellites designed to operate in geostationary orbit at 36,000 kilometers over the equator.

SpaceX has contracted to make its first geostationary launch in 2013, of the SES-8 satellite owned by fleet operator SES of Luxembourg. But the new propulsion system and fairing must be successfully tested during a launch before SES ships SES-8 to SpaceX.

That test flight has not yet occurred, and while SES is maintaining its SES-8 reservation with SpaceX, the operator has secured a backup option with Europe’s Arianespace launch-services provider. SES routinely secures backup options when it books flights even on veteran providers Arianespace of Europe and Reston, Va.-based ILS.

If SpaceX is able to keep to its schedule for geostationary-orbit missions and launch AsiaSat 6 and AsiaSat 8 on time, the ILS contract will revert to the AsiaSat 9 satellite, which AsiaSat has not yet ordered. AsiaSat said in its June 22 announcement that AsiaSat 9 will be built to replace AsiaSat 4 at 122 degrees east in geostationary orbit. AsiaSat 4 was launched in 2003 and has a contracted 15-year service life.

AsiaSat has agreed to pay ILS $109 million for the AsiaSat 9 launch.

A third possibility is that ILS will be needed to launch either AsiaSat 6 or AsiaSat 8, and that AsiaSat still wants to launch AsiaSat 9 aboard an ILS Proton. The contract provides that this option may be exercised for $108 million.

“In view of the possible inflation in the prices for launch services … it is commercially beneficial for the company to secure the provision of a launch service for one of its future satellites,” AsiaSat said in its stock exchange filing in reference to the AsiaSat 9 launch option.