Phobos-Grunt:Russian sample return mission
M.Ya.Marov a,*,V.S.Avduevsky b ,E.L.Akim a ,T.M.Eneev a ,R.S.Kremnev c ,
S.D.Kulikov c ,K.M.Pichkhadze c ,G.A.Popov d ,G.N.Rogovsky c
a
Keldysh Institute of Applied Mathematics,Russian Academy of Sciences,Miusskaya sq.4,Moscow 125047,Russia
b
Center for Wave Mechanics,Russian Academy of Sciences,Bardin str.4,Moscow 117334,Russia
c
Lavochkin Association/Babakin Center,Rosaviacosmos,Lenigradskoe shos,24,Khimki,Moscow Region,141400,Russia
d
Institute of Electrodynamics,Moscow Aviation Institute,Volokolamskoe shos 4,Moscow 125871,Russia
Received 16December 2002;received in revid form 13February 2003;accepted 14February 2003
Abstractrich
As an important milestone in the exploration of Mars and small bodies,a new generation space vehicle ‘‘Phobos-Grunt’’is planned to be launched by the Russian Aviation and Space Agency.The project is optimized around a Phobos sample return mission and follow up missions targeted to study some main asteroid belt bodies,NEOs and short period comets.The principal constraint is u of the ‘‘Soyuz-Fregat’’rather than the ‘‘Proton’’launcher to accomplish the challenging goals.The vehicle design incorporates innovative SEP technology involving electrojet engines that allowed us to increa significantly the mission’s energetic capabilities,as well as highly autonomous on-board systems.Basic criteria underlining the ‘‘Phobos-Grunt’’mission scenario,scientific objectives and rationale including Mars obrvations during the vehicle’s inrtion into Mars orbit and Phobos approach maneuvers,are discusd and an opportunity for international cooperation is suggested.Ó2003COSPAR.Published by Elvier Ltd.All rights rerved.
Keywords:Mars/Phobos;Soil;Space vehicle;SEP;Mission scenario;Ballistic/mass parameters
1.Introduction
After the loss of ‘‘Mars 96’’,an approach to main-taining the Russian planetary program at a moderate level of activity was elaborately studied.Various possi-ble scenarios were assd with the principal goal to meet challenging scientific objectives within the cur-rently existing budgetary constraints (Marov,1997).The study resulted in the development of a new generation space vehicle for planetary exploration.The project is targeted to sample return from Phobos (PSR),with an extended capability of some Main belt (MB)asteroids,NEOs and comets rendezvous.The PSR mission profile has been fully defined and pha B has been completed.The project is a part of the Russian Federal Space program and its launch is tentatively scheduled for 2007,
with a caveat that financial constraints may cau postponement beyond that date.
Why was Phobos lected as a goal of the mission?There exist many intriguing problems related to the nature and origin of the Martian satellites.The main goal is to return a piece of material from a relatively easily accessible small body of the solar system.Scien-tific objectives also include direct in situ and remote nsing measurements of Phobos’surface and environ-ment,as well as some distant
study of Mars during the shaping orbit to approach Phobos and after take offof the return rocket.The experience gained from the former Russian ‘‘Phobos 88’’mission is a great legacy to pursue the mission strategy and concept.The PSR is addresd as an important component of the international program of Mars exploration and mod-ern technology demonstration (Anfimov,1996).The project is a milestone of the Russian planetary program,with a potential to follow up with other ambitious missions.
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Corresponding author.Tel.:+7-95-250-0485;fax:+7-95-250-0485.E-mail address:marov@spp.keldysh.ru (M.Y.Marov).
0273-1177/$30Ó2003COSPAR.Published by Elvier Ltd.All rights rerved.
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doi:10.1016/S0273-1177(03)00515-5
Advances in Space Rearch 33(2004)2276–2280
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2.Scientific objectives
The following scientific objectives are intended to be accomplished with the PSR mission:
•investigation of ancient matter pertinent to asteroid class bodies with remote nsing,in situ techniques and the most challenging goal of delivering samples to Earth for laboratory studies;
•getting more insight into the problem of Phobos/ Deimos origin and their genetic relation to Mars;•study of physical–chemical properties of the Phobos surface and inner structure,with relationship to orbi-tal and rotational motions;
•study of Martian environment at the Phobos orbit and dusty torus(if any);
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•Mars exploration on the inbound pha of PSR mis-sion and during on-Phobos operations;•measurements in interplanetary space and enroute to Mars.
Although the main goal of the‘‘Phobos2’’mission in 1989was not accomplished,a number of important measurements were made,including clo up Phobos images(Fig.1).In particular,spectro-p
hotometric pat-terns of Phobos’surface pod some questions about their nature and the relevant problems of the Phobos and Deimos origin(Ksanfomality and Moroz,1995). Equally important,however,were the results of navi-gation and ballistic measurements obtained during the spacecraft shaping orbit and especially during thefinal pha of Phobos approach.
The experience gained is a great heritage to be utilized for the planned PSR mission while its scenario involving (unlike the‘‘Phobos2’’mission)landing on the surface and sample return,is much superior as compared to the previous one.
3.Mission scenario and profile
As a basic concept,the project pursues u of modern technology and robust engineering to ensure significant cost reduction of planetary missions.The bottom line is the u of middle class Soyuz-Fregat rather than the heavy Proton launcher,which introduces a strong mass constraint.Small propulsion electrojet engines bad on SEP technology are ud to increa the mission’s en-ergetic capability(Avduevsky et al.,2000).This makes it possible to extend the basic PSR mission concept to some other challenging scenarios of solar system ex-ploration.The scenario of the mission is shown in Fig.2 and described as follows:
•launch of the spacecraft and its injection rocket into near-circular LEO(h¼180–200km,i¼51:8°);•inrtion into interplanetary Mars targeted trajectory using the main chemical propulsion engine;
•SEP operation at the Earth–Mars transfer trajectory for about500days;
•deceleration and inrtion into Mars orbit clo to the Phobos orbit followed by shaping orbit to approach Phobos;
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•landing on Phobos at near equatorial plane(0–30°)at the velocity0.5Æ0.2m/s;
•taking samples from up to$1.5m,carrying out on-surface in situ measurements and deploying a small station on Phobos’surface;
•launch of the return rocket on an Earth targeted tra-jectory and in-flight trajectory corrections;
•entry of capsule with samples to the Earth atmo-sphere,landing and rescue operations.
An optimization criterion to share the required ve-locity changes between chemical and electrojet propul-sion was ud as a rationale to increa the effective mass of spacecraft M sc.Parameters in
the Earth–Mars trans-fer trajectory and the emerging mass constraints de-pending on transfer time T are shown in Table1.Here T st is the launch time from intermediate Earth’s orbit; V1E is the‘‘infinity’’velocity when leaving the Earth’s orbit;M sc is the original mass of spacecraft at the Earth–Mars trajectory;T eo is the total SEP operation time; V1M is the‘‘infinity’’velocity when approaching Mars; M Xe is the mass of Xenon utilized;M f is the mass de-livered to Mars(after SEP module detachment);I R is
deep v
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the Fig.1.‘‘Phobos2’’images of Phobos taken in1989.
M.Y.Marov et al./Advances in Space Rearch33(2004)2276–22802277
integral momentum provided by electrojet engines;V x is the characteristic braking velocity at Mars;and T a is the time of arrival to Mars.
SEP operation during the Earth–Mars trajectory (one or two gments of total 362days)is the best strategy.The characteristic velocity required for inrtion into Mars orbit after deceleration with the SEP is only slightly above 900m/s.Several successive maneuvers follow for shaping the spacecraft orbit towards match-ing Phobos’orbit from the original residual of 300km in mi-major axis.The time required to complete the Phobos approach and final mooring stage varies from 120to 150days.The mission profile for the provisional lected launch date in 2007and the basic spacecraft configuration are shown in Figs.3and 4,respectively.The spacecraft is equipped with three SPD-140elec-tric engines with specific trust P sp ¼2100s that ensures the total thrust P ¼38g for the lected parameters:N ¼8:0kW;N c ¼4:0kW.The mass/energy ratio achieved is approximately 10–30kg/kW.Total area of solar arrays is 54m 2,the efficiency being $180W/m 2and the overall SEP system efficiency g ¼40kg/kW.
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Fig.3.PSR mission profile and
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Fig.2.Scenario of PSR mission.
Table 1
Trajectory/mass optimization for PSR mission launch in 2007T (days)T st V 1E (m/s)M sc (kg)T eo (days)V 1M (m/s)M Xe (kg)M f (kg)I R (kN s)V x (m/s)T a
550
01.07.07
1384
2269
362
716
397
1563
7675
947
01.01.09
2278M.Y.Marov et al./Advances in Space Rearch 33(2004)2276–2280
SPD-140engine and Xenon tanks layout are shown in Fig.5.Fig.6shows a general PSR vehicle configuration.
Finally,a sketch of the lander on Phobos’surface with the mooring system,engines for pressing down the surface and other operational systems for taking the soil sample and the return rocket to deliver a capsule with the soil back to the Earth is shown in Fig.7.4.Potential expansion of PSR vehicle
The bottom line for the PSR spacecraft design is its utilization for broad planetary exploration,with an opportunity to fulfill different missions strategies.In particular,it can be targeted to various class of as-teroids and short-period comets.Becau SEP is ad-vantageous at distances between0.3and3.0a.u.
from Fig.5.SPD-140engines and Xenon tanks
layout.
Fig.6.General PSR vehicle configuration(left)and mock up(right).
M.Y.Marov et al./Advances in Space Rearch33(2004)2276–22802279
the Sun,veral Main belt asteroids,comets and NEOs were lected to accommodate the energy consumption parameter J andflight time T required.Asteroids of the inner part of the Main belt(a¼2:2–2:5a.u.;e<0:15; i<15°)of the class U(4Vesta),C(19Fortuna,10 Hygiea),S(6Hebe,20Massalia)and M(21Lutetia),as well as NEO asteroids of433Eros(Tholen, 1989)are addresd as having specific scientific interest and as the most accessible.For a few comet missions under consideration the energy consumption criterion J appeared to be less as compared with the asteroid mis-sions.It is caud by the fact that comet’s perihelion is located clor to the Sun than that of an asteroid and therefore,the energy available for SEP operation is higher.
5.Summary
Modern technology and robust engineering rve as the baline of a new generation ROSAVIACOSMOS space project for planetary exploration with important scientific objectives.Utiliza
tion of a Soyuz-type middle class launcher places mass constraints on the project and ensures significant cost reduction.The incread ener-getic capabilities are provided by utilization of SEP technology.Spacecraft parameters and scientific ratio-nale are optimized around the PSR mission,the goal being accomplished for$3.5years.The PSR mission profile was optimized around a provisional launch date of July–September2007with the derived ballistic/mass parameters.The study establishes an opportunity of rendezvous and/or sample return missions to veral Main belt asteroids,comets,NEOs and Jupiter’s Europa with a modified version of this vehicle. Acknowledgements
Authors are grateful to their colleagues from Lav-ochkin Association.Babakin Center,Central Scientific Rearch Institute for Machinery,Space Rearch In-stitute and Vernadsky Institute for their contribution to the project.Special appreciation is given to the support of ROSAVIACOSMOS that made the project develop-ment feasible.The study was supported by the RFFI Grant#02-02-165.
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