NASA’s New Horizons probe remains on course for its July 2015 encounter with Pluto following a short course correction.

The 35-second thruster firing conducted June 30 keeps New Horizons on track to fly within 12,500 kilometers of Pluto on July 14, 2015, according to the probe’s builder, the Johns Hopkins University’s Applied Physics Laboratory (APL) in Laurel, Md.

APL said in a July 2 mission update that thermal photons from New Horizons’ plutonium-fueled radioisotope thermoelectric generator reflected off the backside of the spacecraft’s high-gain antenna, creating enough force to push the probe off course.

Commands for the course-correction maneuver were transmitted to the spacecraft’s computers June 24; the burn went off as planned June 30.

At the time of the maneuver, New Horizons was 2.4 billion kilometers from Earth, nearing the orbit of Uranus. At that distance, APL said, the radio signal from the spacecraft takes more than 2 hours and 13 minutes to reach Earth.

New Horizons flight controllers at APL received confirmation of the successful firing through NASA’s Deep Space Network antenna station near Madrid, Spain.

The spacecraft launched Jan. 17, 2006, aboard a United Launch Alliance Atlas 5 rocket from Cape Canaveral Air Force Station, Fla.