ISROs SAGA (Supercomputer for Aerospace with GPU Architecture)

ISROs SAGA (Supercomputer for Aerospace with GPU Architecture)

Figure 1. SAGA facility, source [1].

A GPU based supercomputer, SAGA (Supercomputer for Aerospace with GPU Architecture) is developed in VSSC, ISRO. SAGA is based on Intel Xeon processors and nVIDIA GPUs. The supercomputer has a theoretical peak performance of 448 TFLOPS (DP). A GPU based Computational Fluid Dynamics (CFD) software  PARAS-3D has been developed in VSSC. PARAS-3D is a major application software running on SAGA, which is used for CFD analysis of launch vehicles (for example, Fig. 2 and 3). The cluster and infrastructure design was carried out in VSSC. Operating system, job scheduler, automated resource and  power manager are also developed in-house. The supercomputer consists of 736 numbers of Intel Xeon processors 736nVIDIA Tesla GPUs. SAGA uses in-house configured Linux Operating System. The 64-bit Linux operating system (OS)for SAGA is configured using LFS (Linux from Scratch) with support for GPUs and InfiniBand. 

Figure 2. Geometry and Grids for a typical problem. [1]

Figure 3. Pressure contour solution for LVM3 using PARAS-3D, source [1].

PARAS-3D is a Cartesian grid based CFD code that has been developed for SAGA. The CFD code was written for GPUs using CUDA programming model provided by nVIDIA. PARAS-3D has about 2.5 lakhs lines of C-code and is one of the most complex applications running on GPUs. The code is extensively used by ISRO and other aerospace organizations in the country. The advantages of PARAS-3D includes fully automatic grid generation, ability to handle complex geometries, interface for CAD geometries, adaptive grid refinement etc.

[1] SUDHAKARAN.G, THOMAS.C.BABU, ASHOK.V, " A GPU COMPUTING PLATFORM (SAGA) AND A CFD CODE ON GPU FOR AEROSPACE APPLICATIONS".

ISRO considering rendezvous and docking experiment

ISRO considering rendezvous and docking experiment

In the 12^th five year plan of ISRO, a new initiative of Space Docking Experiment has been mentioned.  The experiment will be based on the low impact docking concept (berthing scheme, Fig.1) using two small satellites (IMS-1 class ~ 100 kg, Fig.2). During the plan period a number of small satellite (IMS class) missions have been planned to demonstrate the new emerging technologies. Rendezvous and Docking (RVD) is one of the major missions of technology demonstration . These satellites will be flown on the PSLV missions as auxiliary or co-passenger satellites.

Figure. 1. International low impact docking system.

Figure 2. IMS satellite, ISRO.

Possible Applications: Mastering the RVD technology will help ISRO in future space missions. One possible use could be in orbit servicing of  satellites. ISRO operates large number of  satellites  that are used for communication, remote sensing and soon for navigation purpose. Life of these satellites is limited by the amount of fuel they carry with them in orbit. RVD will allow ISRO to dock a servicing spacecraft with a satellite for the purpose of servicing and refueling. This will increase lifespan of the satellite and save the cost of building replacement satellites. Another advantage of satellite servicing is reduction in space debris as fewer replacements will be required for a satellite. RVD is also critical for Human Space Flight program of ISRO.

ISRO Semi Cryogenic engine & stage development

ISRO Semi Cryogenic engine & stage development

In 2008, ISRO initiated a program to develop semi cryogenic engine technology to allow low cost access to space. The program aims to complete the engine design, fabrication and testing within 6 years. The goal is to develop an extremely efficient, high-pressure staged combustion cycle engine with a vacuum thrust of 2000 kN. The semi cryogenic engine uses a combination of liquid Oxygen and Kerosene (ISRO uses ISROSENE) as propellants which are eco-friendly and cost effective. Using this engine, a semi cryogenic stage will be developed that will constitute the core stage of ISRO’s future launch vehicles (unified launch vehicle (ULV) and re-usable launch vehicles (RLV)).

ISRO has been using solid, hypergolic liquid and cryogenic propellants based stages in its satellite launch vehicles (SLV). ISROs workhorse polar satellite launch vehicle (PSLV) uses alternative solid and liquid propellant based stages where a total of four stages are used. ISRO has also developed cryogenic engine and based on it a cryogenic upper stage (CUS) for its geosynchronous satellite launch vehicle (GSLV MK2).  

Figure 1. Isro's semi cryogenic engine (from presentation of Dr. B.N. Suresh, (VSSC) ).

To bring down the cost of access to space, ISRO now plans to use semi cryogenic propellants based core stage in its future launch vehicles. Semi cryogenic engine has efficiency and cost advantages over engines that use solid and hypergolic liquid propellants. The specific impulse of semi cryogenic engine is higher than its solid and hypergolic counterparts, which means that it can lift a higher payload for the same propellant mass.  In addition, the propellants for semi-cryogenic engine are safer to handle & store, and are more eco friendly. When compared to cryogenic engine, semi cryogenic engine is less efficient, but its advantage lies in comparatively reduced engine design complexity and fuel handling cost.

ISRO has plans for a Semi Cryogenic Stage (SC160) with 160 ton propellant loading powered by the 2000 kN semi cryogenic engine to be used in place of L110 stage of GSLV Mk III. This will enhance the GTO payload capability from 4 T to 6 T. In the 12th FYP this stage development will be initiated.

Updates:
Annual report 2011-2012: Engine design, generation of fabrication drawing of sub systems and integration drawings have been completed. Preliminary Design Review of Engine Gimbal Control system have been completed and technical specification document of both Hydraulic Actuation System and Hydraulic Power System generated. Hypergolic igniter trials have been successfully demonstrated. Single element of pre burner and thrust chamber are realised. 3 tests have been completed for single element Semi cryo pre-burner injector.