Phobos-Grunt’s Mysterious Thruster Activation: A Function of Safe Mode or Just Good Luck?

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Editor’s note: Dr. David Warmflash, principal science lead for the US team from the LIFE experiment on board the Phobos-Grunt spacecraft, provides an update for Universe Today on the likelihood of saving the mission.

The Phobos-Grunt probe is still stuck in orbit around Earth. However, periodically the spacecraft experiences a mysterious slight boost in its orbit.  Following the first episode where this occurred, commentators speculated as to the cause.  The activation of the spacecraft’s thrusters – the small engines that are designed to steer the craft and make small adjustments  — was an obvious answer.

Is spacecraft trying to save itself?

The spacecraft is not responding to any communications, and engineers at the Russian Space Agency Roscosmos have decided that the craft had reverted to a safe mode after the engine of the Fregat rocket stage that was to propel her from a low to a higher orbit around Earth failed to ignite. While in safe mode, the craft had oriented herself to the Sun, using the thrusters to adjust her roll, pitch, and yaw. But to change the parameters of the orbit, she’d need to accelerate, so there was speculation that the needed thrust had come from leaks and venting of gases in a direction favorable to increased orbital stability.

After a second episode during which the altitude increased again, according to Ria Novosti editor-columnist of the journal “News of Cosmonautics” Igor Lisov has reported that a source in the space industry had explained that the probe “Corrects her orbit” every now and then.

Corrects her orbit? Does this mean that the probe knows where she is?

Probably not.

With information coming from Roscosmos being so scarce, reporting on the mission that began was launched on November 9, 2011 has depended on a few official statements from the agency, augmented by speculation from various space experts. Being in safe mode, Grunt simply is waiting for instructions –instructions that controllers are having difficulty delivering, because initial communication was not supposed to take place with the probe at such a low orbit.

If Grunt’s safe mode includes a program that fires thrusters every so often to keep the craft from entering the atmosphere in the event of a malfunction just after reaching low Earth orbit, no statements from Roscosmos have mentioned it, thus far. Whatever the reason, if it continues to occur, we can expect that the predicted date of atmospheric entry will be moved back again, just as it was moved from late December/early November to mid-January after the first orbital correction episode.

The Planetary Society’s Living Interplanetary Flight Experiment (LIFE) capsule, on board the Phobos-Grunt spacecraft. Credit:The Planetary Society

What might this mean for the mission? First of all, perhaps it could buy more time for controllers to establish communication –although Roscosmos has stated that December is the limit for correcting the problem, despite the fact that the probe will be in space at least until mid January. The second thing it could do would be to keep the Planetary Society’s LIFE experiment in space a little longer, which would have benefits only if the Grunt return capsule containing the LIFE biomodule separates from the rest of the craft and makes the reentry and landing that it was designed to do at the end of the flight. This possibility and the potential scientific value is discussed in my previous update, Might the LIFE Experiment be Recovered?

As for the question of why a craft that merely is supposed to find the Sun while in safe mode fires thrusters in a direction that improves the orbit, perhaps it is just good luck, or perhaps it really is part of the safe mode. Until Roscosmos provides more information of what may have caused this, the reason for the orbital correction remains a mystery.

Update on Phobos-Grunt: Might the LIFE Experiment be Recovered?

Phobos-Grunt

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Editor’s note: With Russian engineers trying to save the Phobos-Grunt mission, Dr. David Warmflash, principal science lead for the US team from the LIFE experiment on board the spacecraft, provides an update of the likelihood of saving the mission, while offering the intriguing prospect that their experiment could possibly be recovered, even if the mission fails.

With the latest word from Roscosmos being that the Mars moon probe, Phobos-Grunt is “not officially lost,” but yet remains trapped in low Earth orbit, people are wondering what may happen over the next several weeks. Carried into space early Wednesday morning, November 9, Moscow time, atop a Zenit 2 rocket, Grunt, Russian for “soil”, entered what is known in space exploration as a parking orbit. After the engine of the Zenit upper stage completed its burn, it separated from another stage, known as Fregat, which now still remains attached to Phobos-Grunt. Ignition of the Fregat engine was to occur twice during the first five hours in space. The first Fregat burn would have taken the spacecraft to a much higher orbit; the second burn, about 2.5 hours later would have propelled the probe on its way to Mars and its larger moon, Phobos. From this moon, a sample of soil would be scooped into a special capsule which would return to Earth for recovery in 2014.

Grunt is still in a low orbit, because neither Fregat burn occurred. While the spacecraft is believed to be in safe mode and even has maneuvered such that its orbital altitude has increased, controllers have been unable to establish contact to send new commands. If communication cannot be established, it will re-enter the atmosphere.

In addition to the sample return capsule, Grunt carries an instrument package designated to remain on the Phobosian surface, plus a Chinese probe, Yinghuo-1, designed to orbit Mars. The mission also includes the Planetary Society’s Living Interplanetary Flight Experiment (LIFE) , for which I serve as principal science lead of the US team. Carried inside the return capsule into which the Phobosian soil is to be deposited, LIFE consists of a discoid-shaped canister, a biomodule, weighing only 88 grams. Inside are 30 sample tubes carrying ten biological species, each in triplicate. Surrounded by the 30 tubes is a sample of soil with a mixed population of microorganisms, taken from the Negev desert in Israel to be analyzed by Russian microbiologists.

The Planetary Society’s Living Interplanetary Flight Experiment (LIFE) capsule, on board the Phobos-Grunt spacecraft. Credit:The Planetary Society

Organisms carried within the LIFE biomodule include members of all three domains of Earth life: bacteria, archaea, and eukaryota. The purpose of the experiment is to test how well the different species can endure the space environment, akin to microorganisms moving in space within a meteoroid ejected from Mars by an impact event. If organisms can remain viable within rock material that is transferred naturally from Mars to Earth, it would lend support to the Mars transpermia hypothesis –the idea that life on Earth may have began by way of a seeding event by early organisms from Mars.

We know of microorganisms that could survive the pressures and temperatures associated with the ejection itself. We also know that during atmospheric entry, only the most outer few millimeters of rocks are heated on their way to Earth; thus, anything alive in a rock’s interior at this point should still be alive when the rock hits Earth as a meteorite. If life forms also could survive the journey itself from Mars to Earth, a Martian origin for Earth’s life would be a major possibility. It also would mean that life originating on its own anywhere in the Cosmos could spread from each point of origin, thus increasing the number of living planets and moons that may exist.

Numerous studies of the survivability of many of the LIFE species have been conducted in low Earth orbit, but much of the challenge to life in space comes from highly energetic space radiation. A large portion of space radiation is trapped by a system of magnetic fields known as the Van Allen radiation belts, or the geomagnetosphere. Since very few controlled studies of microorganisms, plant seeds, and other life have been conducted beyond the Van Allen belts, which reach an altitude of about 60,000 kilometers (about 1/7th the distance to the Moon), the Planetary Society arranged to have the LIFE biomodule carried within Grunt’s return capsule.

Over last weekend, the spacecraft surprised everyone by maneuvering on its own, raising its orbit. Due to this, the estimated reentry date was moved back from late November to mid January, meaning that the LIFE biomodule will be in space for more than nine weeks. An intriguing possibility that looms as controllers consider how the mission might end is that the Grunt sample return capsule will break off from the rest of the craft intact. If this happens, it could assume the stable atmospheric entry, descent, and landing that were expected after the return from Phobos. If this happens and the capsule comes down on land, we could recover the LIFE biomodule and test the state of the organisms packaged within it. The result of yet another biological test in low orbit, it would not be the experiment of our dreams. But, amidst the loss of a mission into which so many engineers and scientists have invested their dreams, a little bit could mean a lot.