Deep Space

The first experiments with the thermal electric engine were conducted in Russia in 1929 by its inventor, Valentin P. Glushko, who later became a world-famous authority in rocket propulsion. For more than forty years, the United States and Russia have devoted many resources to research and development of various kinds of EREs. First tested in space by the Russians in 1964, these engines have found some limited applications in modern space technology. For more than two decades Russian weather and communication satellites have regularly used electric rocket engines for orbital stabilization. The first spacecraft to employ ERE for main propulsion was the American asteroid exploration probe Deep Space 1, launched in 1998. The performance of... 

Images of comet nuclei taken during various spacecraft encounters illustrate both similarities and differences. Figure 12.2 compares images of comets Borrelly (taken by Deep Space 1 in 2001), Wild2 (taken by Stardust in 2004), and Tempel 1 (taken by Deep Impact in... 

Laboratory New Millennium Deep Space 1 satellite. The company s concentrating lenses cut the total array cost by as... 

Figure 6 Stereo images of comet Borrelly taken by NASA s Deep Space 1 Mission.

Figure 5 Active jets observed from comet Borrelly. This directed emission from sunlit areas is responsible for the rocket effect that measurably perturbs many comet from normal Keplerian orbits purely determined by gravity. Image taken by NASA s Deep Space 1 Mission.

A second successful U.S. comet mission was Deep Space 1, launched from Cape Canaveral on October 24, 1998. Its principal goal was to test a variety of new space technologies. It completed this primary mission in Septemher 1999. The spacecraft s mission was then extended to include a flyby of Comet Borrelly, which it accomplished on Septemher 22, 2001. Deep Space 1 sent hack black and white photographs of the comet, infrared spectrometer readings, ion and electron data, and measurements of the magnetic held and plasma waves in the vicinity of the comet. 

Not all space missions to comets have been as successful as Stardust and Deep Space 1. For example, NASA s CONTOUR (Comet Nucleus Tour), launched on July 3, 2002, was designed to rendezvous with and study Comet Encke on November 12, 2003, and Comet Schwassmann-Wachmann 3 on June 18, 2006. All contact was lost with CONTOUR on August 15, 2002, however, and the mission was canceled. 

Deep Space 1 was taken out of service in December 2001. During its three years in space, it has trialled a number of new technologies and proved the future potential of the xenon propulsion system. 

Deep Space 1 (Technology Demonstration) Launched on Octoher 27,1999... 

With the launch of Deep Space 1 in 1998, the autonomous systems community celebrated a milestone— the first flight experiment demonstrating the feasibility of a fully autonomous spacecraft. We anticipated that the advanced autonomy demonstrated on Deep Space 1 would soon be pervasive, enabling science missions, making spacecraft more resihent, and reducing operational costs. 

Where do we stand today in terms of deployed mXoitomo s systems Specifically, which of the technology elements that comprise a complex, self-sufficient, intelligent system have flown in space There have been several notable successes. Four milestone examples illustrate the progress made Deep Space 1, which flew the first operational autonorrty in space Earth Observing 1, which demonstrated autonomous collection of science data Orbital Express, which autonomously carried out spacecraft servicing tasks and the Mars Exploration Rovers, which... 

FIGURE 2 Deep Space 1 flew the Remote Agent Experiment, which demonstrated full spacecraft autonomy for the flrst time. Figure courtesy of NASA/JPL-Caltech. 

The most mature of the electric propulsion concepts is electrostatic propulsion. NASA s Deep Space 1 device (Figure 2), launched in 1998, relies on an ionized xenon gas jet for propulsion (Brophy, 2002). The xenon fuel fills a chamber ringed with magnets, which control the flow electrons emitted from a... 

FIGURE 2 Schematic drawing of the Deep Space 1 ion thruster. Source NASA, 2002. 

Brophy, J. 2002. NASA s Deep Space 1 ion engine. Revue of Scientific Instruments 73(2) 1071-1078. 

Spacecraft missions like GIOTTO (see Fig. 5.3) (comet Halley) and Deep Space 1 (comet Borrelley) have shown that cometary nuclei are very dark (albedo less than 0.04). 

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