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Previous chapter: Phobos-Grunt development in 2008-2009
Following the false start of the Phobos-Grunt mission in 2009, the developers of Russia's flagship planetary spacecraft were gearing up for another launch attempt to Mars in 2011. Even with the additional two years afforded by the launch delay, many serious challenges had to be resolved to make Russia's first mission beyond Earth orbit since 1988 a reality.
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On Nov. 24, 2009, NPO Lavochkin, the prime developer of the Phobos-Grunt mission publicly made the long-expected announcement about the vacancy of the Director General - Designer General position at the organization. According to the company's press-release, the contract with the current head of NPO Lavochkin, Georgy Poleshyuk, would expire on Jan. 31, 2010. A formal tender for the new position was conducted on Jan. 20, 2010. Doctor Viktor Vladimirovich Khartov, a veteran engineer at ISS Reshetnev (former NPO PM), was appointed as the new head of the organization. Along with Khartov, two other former employees of ISS Reshetnev took key positions at NPO Lavochkin.
Khartov faced a difficult dilemma with Phobos-Grunt. After the cancellation of the launch in 2009, the spacecraft was mostly disassembled for further upgrades. In the remaining time, electric tests had to be completed and the final design documentation issued. More importantly, no flight program or its algorithms were ready barely year and half before launch. However delaying the launch beyond 2011 would push many critical components of the spacecraft beyond their operational warranties, potentially making the mission impossible.
In March 2010, the Deputy Chief of the Russian space agency, Roskosmos, Anatoly Shilov, was quoted by the official Interfax AVN news agency as saying that the remotely controlled robotic arm for taking samples of soil onboard Phobos-Grunt would be "replaced" with a drilling mechanism. Shilov referred to the Russian Academy of Sciences' conclusion that the existing method of soil sampling on Phobos-Grunt was unusable. According to Shilov, the disqualification of the sampling device was one of the reasons for the mission delay from 2009 to 2011. He did not specify when the problem had been discovered nor explained why the agency continued denying reports about the inevitable delay of the mission until just weeks before the launch window of 2009. In addition, the statement contradicted previous reports that a robotic arm had been chosen in the first place to avoid potential problems with a drilling mechanism in the low-gravity of Phobos. Shilov also promised stable funding for Phobos-Grunt and the special attention of the agency to the project.
Russian space scientists later clarified that a thorough analysis of the possible surface properties on Phobos did show that in some extreme cases, the moon's soil could be too hard for the available systems to penetrate. As of 2009, Phobos-Grunt was to be equipped with a pair of remote manipulators developed by NPO Lavochkin and by the Space Research Institute, IKI, respectively. They used different grapple mechanisms, however both relied on their capability to scratch the surface in order to pick sandy soil and small rocks. Both Russian devices had a limit on the amount of pressure they would apply to the surface, in order not to cause any movement of the lander in the extremely weak gravity of the Martian moon. With the properties of the soil largely unknown, Russian developers did not attempt to design any mechanisms, which would anchor the spacecraft to the surface. Special vernier thrusters would be used to press the lander onto the surface during landing. However no engine firings were planned during the soil-sampling process.
On April 8, 2010, the Polish Academy of Sciences announced that six days earlier its Center for Space Research had reached an agreement with NPO Lavochkin and IKI on the development of a CHOMIK ("hamster") "soil-sampling device" for the Phobos-Grunt project. According to the official press-release, the special drill developed by Polish scientists would be based on a device originally developed for the European Philae lander and designed to work on the icy surface of a comet. The two-kilogram drill had a simple design and required only 1.5 Watts of electricity to operate. In addition, CHOMIK's no recoil mechanism would be gentle enough not to overturn the Russian lander in the weak gravity of Phobos, as was feared could happen with the use of previous drilling systems.
Although the Polish press-release stated that the device would be used only if the primary method of soil sampling failed, the document posed more questions than it answered. At least in some translations from original Polish reports, CHOMIK was identified as a soil-sampling mechanism and misinterpreted as a replacement for a Russian-built remote manipulators. In the meantime, references in the document to a Polish soil container implied the need to redesign the system for storing and transporting the regolith into the return capsule on Phobos-Grunt.
Russian sources later explained that the Polish mechanism would only be used as an auxiliary to the robotic arm and only in case the manipulator failed to penetrate the moon's unexpectedly hard surface. Under such a relatively unlikely scenario, CHOMIK would be used as a jackhammer to produce debris and would collect them into a special container which would be then picked by one of two manipulators on the spacecraft. Manipulators would then place the samples into a special receptacle for the following delivery of the soil into the return capsule via a "pneumatic mail system." (Pressurized gas stored in a special tank would power the system). No major re-design of any existing devices onboard Phobos-Grunt would be required, beyond a relatively simple integration of the Polish mechanism into the probe's flight control system. CHOMIK would be physically attached to the front section of the Lavochkin-built manipulator, which would bring the mechanism to a particular area on the surface. A prototype of the Polish drill was expected in Moscow in the middle of 2010 and the actual flight version of the device would be delivered for installation on the spacecraft by the end of the year.
"Intelligent vision" for Phobos
Scientists at Space Research Institute, IKI, also used the available time for further rehearsals of the complex choreography of soil-sampling on the surface of the Martian moon. A special system of "technical vision," sporting a panoramic camera and a stereo camera was developed to assist ground control in choosing the most intriguing locations for soil sampling. Due to the almost 20-minute delay in the arrival of TV and radio-signals to Earth from Martian distances, scientists hoped to rely on a highly intelligent image assessment technology which could automatically survey the surrounding landscape and “tell” the robotic arm where to go to pick samples. As always in geology, rocks would be the most attractive targets. With a full day on Phobos lasting under eight hours, the mission would have roughly three-hour periods of “daylight” to conduct observations of the surrounding landscape.
In previous years, IKI had not had enough time to thoroughly work out this system. During 2010, IKI scientists were refining the technology at a special test facility imitating the landing site on Phobos, but actually located at NPO Lavochkin, in the Moscow suburb of Khimki. This work was expected to continue for about a year, until the Phobos-Grunt spacecraft would be ready for delivery to the launch site.
All the publicity surrounding the soil sampling mechanism on Phobos-Grunt was only a smokescreen obscuring the real stumbling block before the project. The immaturity of the flight control system, which was the main reason the spacecraft had never had a chance to fly in 2009, still remained the biggest challenge for the project in 2010.
On its way to Mars, Phobos-Grunt, including its propulsion stage, would be controlled by a single flight control computer. (Known as Main Propulsion Unit, or MDU, the propulsion system of Phobos-Grunt was based on the versatile Fregat upper stage. In all previous missions, Fregat would carry its own flight control computer.) A smaller computer would be installed on the return vehicle of Phobos-Grunt for control during the flight back to Earth.
To complete the probe's flight control system, two test stands had to be built at NPO Lavochkin, one for the main flight control computer and another for the return vehicle. All the algorithms of the mission, including nominal and emergency flight modes, would have to be thoroughly and continuously tested before a new launch attempt in 2011 and during the mission itself. The project was supported by the Russian Academy of Science's Institute of Applied Mathematics, an organization with experience in orbital mechanics dating back to the dawn of the Space Age.
NPO Lavochkin's management also made sure that the relatively new team responsible for the flight control system on Phobos-Grunt had unimpeded exchange of information with other departments with experience in avionics for the Karat spacecraft platform and, possibly, for classified military satellites.
The 2007 decision to add a Chinese spacecraft and associated hardware to the Phobos-Grunt probe led to a considerable increase in the overall height of the vehicle. As a result, attitude control thrusters installed at the tips of the spacecraft's solar panels were no longer efficient in orienting the whole vehicle in flight. To resolve the problem, the developers added special fly wheels to the probe, which would help to resolve attitude control problems. However these devices required considerable amount of electrical power, which along with additional power demands from the Chinese spacecraft, overloaded the original power supply system, SES, onboard Phobos-Grunt. Plans to enlarge solar panels onboard the spacecraft were limited by the restrictions of the payload fairing of the launch vehicle.
There were conflicting reports on possible solutions to the problem. According to one posting on the online forum of the Novosti Kosmonavtiki magazine, less than a year before launch, developers faced a major redesign of the power supply system, which was equivalent to its development from scratch. Another poster claimed that the problem with fly wheels (at least) had been resolved. However by the end of 2010, it was still unclear whether the deficiencies of the power supply system, along with continuous problems in the development of the flight control system could prevent the launch of the Phobos-Grunt mission in 2011.
As it transpired after the launch, NPO Lavochkin management had re-appointed a number of experienced specialists in power-supply systems back into the Phobos-Grunt project, reversing radical personnel changes made previously. To their horror, veteran engineers discovered that following the separation of the launch vehicle and the external tank of the MDU propulsion unit from Phobos-Grunt, more than 20 cables would end up short-circuited through the body of the spacecraft. The problem required a complete rebuilding of the onboard cable network with only a year left before the 2011 launch window. Due to a wide-spread use of soldering of cables instead of mechanical connectors, repairs proved very difficult.
Previous concerns about inadequate ground facilities to support a Russian deep-space mission were at least partially addressed by a Russian agreement with the National Space Agency of Ukraine, NKAU. According to NKAU's statement, from May 25 to May 28, 2010, the RT-70 radio-telescope in Evpatoria in the Crimean Peninsula successfully acquired telemetry from the European Mars Express spacecraft, orbiting the Red Planet. According to the Ukrainian statement, Phobos-Grunt would carry a telemetry system similar to the one used onboard Mars-Express. During the tests, the RT-70 telescope was working in the X-band of radio waves, in conjunction with a data receiving and processing complex developed by NPO Lavochkin. Experiments reportedly demonstrated the high degree of readiness of the facility for participation in Phobos-Grunt and other projects. In October 2010, the head of Russian space agency, Anatoly Perminov, personally dropped by the Crimean tracking site, during his visit to Ukraine to discuss cooperation with the country's space officials.
It is understood that the facility in Crimea, a former home of the main Soviet deep-space communications center, TsDKS, would be yet another ground-control asset available to support the Phobos-Grunt mission. Inside Russia, facilities in Medvezhiy Ozera, near Moscow and in Ussuriysk in the Far East were also undergoing upgrades during 2010, which would enable them to serve as primary control sites for the Phobos-Grunt mission. Delays in renovations of those two sites also precluded the launch of Phobos-Grunt in 2009.
In December 2010, Perminov promised an agreement on space cooperation with NASA, which would include the participation of US ground assets in the control of the Phobos-Grunt mission. Industry sources also discussed the possibility of using European ground control in the project.
In September 2011, on the eve of the Phobos-Grunt launch, the Svyaznik complex at Site 23 in Baikonur was upgraded to include the Spektr-Iks telemetry complex. Despite a relatively small size of the antenna, the latest highly sensitive hardware promised to enable the control of deep-space probes up to a distance of several million kilometers, according to Roskosmos.
The 2011 launch window required more energy to send a spacecraft on its way to Mars than would have been needed during the 2009 launch opportunity. To resolve the problem, NPO Lavochkin was working to modify the Fregat-based Main Propulsion Unit, to accommodate extra propellant. Enlarged spherical extensions were welded onto the main tanks of the stage to increase the overall volume. NPO Lavochkin developed three types of tank extensions which were available for the Fregat-based upper stages.
Despite some garbled reports from China that it would abandon cooperation with Russia on the Phobos-Grunt mission after the 2009 launch fiasco, space officials in Moscow insisted that the Chinese hitchhiker satellite would return to NPO Lavochkin after routine maintenance. However, some modifications of the satellite were apparently conducted since Chinese representatives asked NPO Lavochkin to postpone the delivery date for the YH-1 spacecraft from July 2010 until the end of the year.
Finnish lander dropped
One important element of the Phobos-Grunt's original flight scenario had to be omitted. According to Russian officials, plans to release an experimental Mars lander during the mission was abandoned. A small vehicle, built by the Finnish Meteorological Institute, was to be stored in the empty instrument section of the Fregat propulsion stage. Once released, the lander would use an inflatable reentry device to penetrate the Martian atmosphere and land meteorological instruments on the surface of the Red Planet. The experiment would validate a future mission which would carry an entire network of similar probes for global monitoring of Martian weather.
Another critical aspect of the Phobos-Grunt mission, which was waiting clarification in 2010, was the return to Earth of the capsule with precious soil samples from Phobos.
From the outset, Russian developers had decided not to rely on any active landing systems, such as radio-beacons, to locate and recover the tiny vehicle. They cited the mass limitations of the capsule and the dangers of relying on electronic gear which would have to function flawlessly after a multi-year journey to the Martian orbit and back.
Instead ground-based radar and optical observations would be the sole means of tracking the vehicle during its reentry and of pinpointing the site of its touchdown. As a result, mission developers quietly chose the Sary Shagan test range in Kazakhstan, as the primary landing site of the Phobos-Grunt mission. The birthplace of the Soviet anti-missile defense systems, Sary Shagan still serves as a key test base for Russian anti-missile interceptors and their radar. After the end of the Cold War, the center retained some of the systems designed to detect high-velocity objects in the atmosphere and in near space.
To prove the landing concept of the Phobos-Grunt mission, NPO Lavochkin conducted helicopter drop tests which did confirm that the radar at Sary Shagan could detect and track the probe's tiny capsule. Still, many aspects of the landing, including the training of search and recovery personnel remained to be resolved.
In September 2010, the TsAGI institute announced that it had reached an agreement with NPO Lavochkin for a series of tests of the Phobos-Grunt reentry capsule, including simulations in the T-105 vertical wind tunnel, calculation of the capsule's aerodynamics, which would take into account uneven burn off of its ablative thermal shielding and modeling of the movement of the vehicle under the most realistic conditions. The research had the goal of narrowing down the expected landing area for the capsule, TsAGI said.
Simultaneously, mission planners considered alternative options for landing. According to several sources within the space industry, some informal contacts between Russian and US space officials discussed the possibility of ending the Phobos-Grunt mission on US territory. In case of landing in the US, unmatched American anti-missile defense assets could be employed in tracking the capsule, thus providing the most reliable option for the successful conclusion of the mission. However, the scenario would come with strings attached. Even very preliminary discussions with US representatives led to American requests to provide samples of Phobos, Russian officials said. Although Russia was prepared to share scientific knowledge delivered by Phobos-Grunt, proposals to distribute the most valuable fruits of the mission in exchange for technical assistance could create a dangerous precedent, given the international nature and the high risk of the project.
Mission developers preferred that any international agreements on studies of the 100-200 grams of soil samples which could be expected from Phobos-Grunt, would be inked by the Russian Academy of Sciences, possibly after the successful completion of the mission. Russian sources also hinted that priority in the scientific research enabled by Phobos-Grunt could become a political issue. Preparing for the first Russian planetary mission in almost two decades, the nation's scientific community was understandably sensitive about access procedures to Phobos-Grunt's scientific harvest. The situation was exacerbated by the thinly veiled anti-Russian attitude of the leading publishers of scientific papers in the West. Journals like Science and Nature were known to snub research by Russian scientists. A recent review of Nature, had found that 100 issues of the magazine published during 2003-2004 did not contain a single article written independently by a researcher based in Russia. (402) The author of the review, an internationally recognized planetary scientist himself, described the blatant stone-walling tactics of gatekeepers at Nature, which they employed to reject submitted articles.
According to the official schedule, beginning in June 2010, the scientific instruments of the Phobos-Grunt spacecraft, which were undergoing refurbishment at the IKI research institute, had to be returned to NPO Lavochkin for re-installation on the spacecraft.
Between July and November 2010, all flight instruments and systems had to be returned and re-installed. These included most of scientific instruments and some sub-systems of the spacecraft, such as radio hardware.
In February 2011, the flight version of the Phobos-Grunt spacecraft was scheduled to undergo its most rigorous tests at the thermal and vacuum chamber at NITs RKP test center in Peresvet. This work could continue up to three months. However, during the meeting of the Chief Designer Council on March 30, 2011, it was reported that the preparations for the shipment of the spacecraft to the thermal and vacuum testing facility was in the process of completion. Still, the official press-release issued after the meeting claimed that the work had been conducted on schedule.
The flight vehicle was to be shipped to Baikonur in August–September 2011 in preparation for the opening of the launch window to Mars in December 2011. Thus, the Phobos-Grunt team would spend much less time in Baikonur than their predecessors, when they were preparing Soviet deep-space missions. With the significant decay of test facilities at the Kazakh launch site, all critical tests of the spacecraft had to be transferred to Russia. Only the simplest electrical and interface checks were left to be conducted in Baikonur before the integration of the probe with its launch vehicle.
A summary of pre-launch milestones in the Phobos-Grunt project, as of October 2010 (432):
Next chapter: Phobos-Grunt project in 2011
Page author: Anatoly Zak; Last update: January 30, 2012
Page editor: Alain Chabot; Last edit: March 18, 2011
All rights reserved
In January 2010, a veteran space engineer, Viktor Khartov, was appointed Chief Designer of NPO Lavochkin, the prime developer of the Phobos-Grunt project. Click to enlarge. Copyright © 2010 Anatoly Zak
Robotic arm developed at NPO Lavochkin for Phobos-Grunt mission. Credit: NPO Lavochkin
A Mars rover presented by NPO Lavochkin in 2009 featured a robotic arm resembling the soil sampling manipulator, which the company was developing for the Phobos-Grunt mission. Copyright © 2009 Anatoly Zak
Autonomous thermo-vacuum tests of systems for the return module of the Phobos-Grunt spacecraft. (432)
Integrated thermo-vacuum tests of the fully assembled return module of the Phobos-Grunt spacecraft. (432)
Integrated thermo-vacuum tests of the landing module for the Phobos-Grunt spacecraft. (432)
The Phobos-Grunt spacecraft assembled. Click to enlarge. Credit: NPO Lavochkin
Vibration and static tests of the Phobos-Grunt. (432)
Tests of transportation loads on the spacecraft. (432)
Click to enlarge. Credit: NPO Lavochkin
Testing of the Phobos-Grunt spacecraft in a centrifuge facility at NPO Lavochkin in Khimki near Moscow. Click to enlarge. Credit: NPO Lavochkin