Posted on by Bob King

NASA Loses Contact with New Horizons; Probe Now in Safe Mode

For a nail-biting hour and 20 minutes, NASA lost contact yesterday afternoon July 4 with the New Horizons spacecraft just 9 days before its encounter with Pluto. Communication has since been reestablished and the spacecraft is healthy.

(UPDATE July 6: Great news! The mission will return to normal science operations July 7 – more details below.) 

At 1:54 p.m. EDT, communications suddenly stopped and weren’t reestablished until 3:15 p.m. through NASA’s Deep Space Network. During the time it was out of contact with mission control, the spacecraft’s autonomous autopilot recognized the problem and did what it was programmed to do, switching from the main to the backup computer, according to NASA officials. The autopilot then commanded the backup computer to put New Horizons in “safe mode” — where all non-essential functions are shut down — and reinitiate communications with Earth.

Artist view of New Horizons passing Pluto and three of its moons. The ship is about the size of a grand piano and kept warm in the cold of the outer Solar System by heat release from the radioactive decay of plutonium within the probe's RTGs (Radioisotope Thermoelectric Generator). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Artist view of New Horizons passing Pluto and three of its moons. The ship is about the size of a grand piano and kept warm by heat released from the radioactive decay of plutonium within the probe’s RTG (Radioisotope Thermoelectric Generator). To further retain heat in the frigid cold far from the Sun, it’s insulated with multi-layer blankets. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Success! We’re now back in touch with the spacecraft and engineers are monitoring telemetry to figure out what went wrong.  New Horizons is presently almost 3 billion miles (4.9 billion km) from Earth. Due to the 8.8 hour, round trip communication delay, full recovery is expected to take from one to several days. During that time New Horizons will be unable to collect science data.

If there’s any upside to this, it’s that it happened now instead of 9 days from now. On July 14 at 7:49:57 a.m. EDT  the spacecraft will pass closest to Pluto.

Check back for updates. In the meantime, you can watch a live connection between New Horizons and the Deep Space Network. The probe is labeled NHPC and the dish 63 (first entry).

UPDATE: July 6. NASA announced earlier this morning that has concluded the glitch that caused the New Horizons spacecraft to go into safe mode was not due to a software or hardware fault.

“The underlying cause of the incident was a hard-to-detect timing flaw in the spacecraft command sequence that occurred during an operation to prepare for the close flyby. No similar operations are planned for the remainder of the Pluto encounter,” according to a NASA release.

No primary science will be lost and secondary goals were only slightly compromised. Mission control expects science operations to resume on July 7 and to conduct the entire close flyby sequence as planned.

“In terms of science, it won’t change an A-plus even into an A,” said New Horizons Principal Investigator Alan Stern.

Whew! What a sense of relief. Onward!

18 Replies to “NASA Loses Contact with New Horizons; Probe Now in Safe Mode”

  2. Must be a tense time for NASA.

    Fingers crossed they can troubleshoot & resolve this hiccup without affecting the scheduled science & imaging goals.

    1. In the last 10 days during a 10 year trip? It did happen once before and put NH in safe mode for two days. Cosmic rays aren’t excluded and it is a convenient excuse, but they certainly are looking for problems they can control.

  7. Coincidence just days before it gets there OR something more SINISTER??? Come on NASA the World is watching….

    1. Now is an appropriate moment for one of those famous Jean Luc Picard facepalms.
      I just *knew* the conspiracy, NASA-has-something-to-hide, nuts were going to pop out of the woodwork when they heard about this.

      1. Perhaps the Universe is just messin’ with us…nothing like a little expectation anxiety to liven up the proceedings. 😉

  9. “The underlying cause of the incident was a hard-to-detect timing flaw in the spacecraft command sequence that occurred during an operation to prepare for the close flyby” …for anyone that knows computers and software, we can easily see that it was a command error sent from Earth… example : same computer , put XP on it – serial BSOD…put win7 and it suddenly works flawless…

    1. A computer is like an air conditioner; neither works properly if you’ve got Windows open.

  11. YES! A simple timing glitch in the software! Minor miracles are welcome… This gives me hope that SpaceX will find an easy fix for the Falcon IX?

  12. whew… glad I came across this after the problem had already been solved.

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