Transfer vehicles on the basis of solar power-propulsion system (SPPS)

Area of SPPS application

Transfer vehicles (TV) on the basis of SPPS have been providing highly effective delivery of space vehicle (SV) from low reference orbits to interplanetary trajectories, high-elliptical and high circular orbits (including GEO) for 10...60 days.

SPPS principal advantages

· As compared to the conventional LRE and SRM:
- substantially greater efficiency on fuel flow rate (up to 2.5 times);
- high adaptability providing a possibility to manufacture a common multipurpose TV for the main group of operational and developed in the world launch vehicles (LV) of average and heavy classes (from LV "Soyuz-2" up to LV "Arian-5" and "Proton-M").

· As compared to electrojets:
- reduced in 5:10 times duration of SV delivery to GEO;
- lesser dependence of SPPS application efficiency from power of SV solar arrays.

Goals achieved by development and application of SPPS

Effective way of increasing the carrying capacity of insertion facilities to GEO up to 2 times.

Great extension of the possibilities in choice of LV for performing a specific problem.

Reduction of SV insertion into GEO up to 2 times as compared to he conventional PS.

High reliability and efficiency of fulfillment of he space programs and commercial launches owing to the possibility of timely and effective replacement of one type of LV with the other one (for example, in the case of non-readiness of the LV chosen earlier).

Transfer vehicle with SPPS

MAIN CHARACTERISTICS of SPPS Sustainer engine of SPPS can operate in the mode of usual LRE (on cold components) as well as in pulse-periodical modes with discharge of heat accumulator: - work with afterburning of hot hydrogen (mode 1); - work on hot hydrogen without afterburning (mode 2). Long continuous thrust modes are reached by operation of electrojets.

SPPS characteristics	LRE mode	Pulse-periodical modes		Continuous mode
		1	2
Electrical power, kW	-	10...15 (15)
Fuel components	Н2+О2	Н2+О2	Н2	Н2
Mixture ratio of oxygen and hydrogen	5	1...5	0	0
Thrust, N	360	150...400	100	2...3 (4)
Specific Impulse	462	585...510	750	810 (660)
Temperature of hydrogen heating, K: - in accumulator - in electrojets	- -	1500	2000	2400 (1600)

Note: The parameters of the variant of SPPS of the 1st stage are indicated in the brackets (with rated characteristics already achieved in the course of testing) used in commercial launches of geostationary SV from the foreign space bases; operating mode of sustainer engine without afterburning (mode 2) is lack in this variant.

Efficiency of universal TV with SPPS in the task of SV delivery to GEO

The work on assembly and testing of the experimental model of the prime engine to provide project-design works on transportation module on the basis of solar thermal propulsion system.

According to the design documentation of FSUE "Keldysh Research Center" Cheliabinsk's electrode plant manufactured and delivered the pilot batch of the parts for assembly of heat accumulator.