Innovative Explorer mission to interstellar space

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2005

An interstellar "precursor" mission has been under discussion in the scientific community for over 25 years. Fundamental scientific questions about the interaction of the Sun with the interstellar medium can only be answered with in situ measurements that such a mission could provide. The Innovative Interstellar Explorer is a funded NASA Vision Mission Study that investigates the use of Radioisotope Electric Propulsion (REP) to enable such a mission. The problem is the development of a probe that can provide the required measurements and can reach a heliocentric distance of at least 200 astronomical units (AU) in a reasonable mission time. The required flyout speed in the direction of the inflowing interstellar medium is provided by a high-energy launch, followed by long-term, low-thrust, continuous acceleration. Trades from also using gravity assists have been studied along with trades between advanced Multi-mission radioisotope thermoelectric generators (MMRTGs) and Stirling radioisotope generators (SRGs), both powered by Pu-238. While subject to mass and power limitations for the instruments on board, such an approach relies on known General Purpose Heat Source (GPHS), Pu-238 technology and current launch vehicles for

2002

44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2008

Studies over the last decade have shown radioisotope-based nuclear electric propulsion to be enhancing and, in some cases, enabling for many potential robotic science missions. Also known as radioisotope electric propulsion (REP), the technology offers the performance advantages of traditional reactor-powered electric propulsion (i.e., high specific impulse propulsion at large distances from the Sun), but with much smaller, affordable spacecraft. Future use of REP requires development of radioisotope power sources with system specific powers well above that of current systems. The US Department of Energy and NASA have developed an advanced Stirling radioisotope generator (ASRG) engineering unit, which was subjected to rigorous flight qualification-level tests in 2008, and began extended lifetime testing later that year. This advancement, along with recent work on small ion thrusters and life extension technology for Hall thrusters, could enable missions using REP sometime during the next decade.

Energy Conversion & Management, 2008

The exploration of space both by humans and robots has been greatly enhanced and, in many cases, enabled by the use of radioiso-tope power sources (RPSs) to power and/or heat scientific instruments. Radioisotope power sources have enabled such breakthrough missions as the Pioneer flights to Jupiter, Saturn and beyond; the Voyager flights to Jupiter, Saturn, Uranus, Neptune, and beyond; the Apollo lunar surface experiments; the Viking Lander studies of Mars; the Galileo spacecraft that orbited Jupiter; the Ulysses mission to study the polar regions of the Sun; the Cassini spacecraft orbiting Saturn; and the recently launched New Horizons spacecraft to Pluto. Radioisotope heater units have enhanced or enabled the Apollo Early Scientific Experiment Package and the Mars exploration rover missions (Sojourner, Spirit and Opportunity). Since 1961, the United States has successfully flown 41 radioisotope thermoelectric generators (RTGs) to provide electrical power for 23 space missions. Published by Elsevier Ltd.

Acta Astronautica, 2011

Nuclear Electric Propulsion (NEP) is a technology conceptually proposed since the 1940s by E. Stuhlinger in Germany. The JIMO mission originally planned by NASA in the early 2000s produced at least two designs of ion thrusters fed by a 20-30 kW nuclear powerplant. When compared to conventional (chemical) propulsion, the major advantage of NEP in the JIMO context was recognized to be the much higher I sp (lab-tested at up to 15,000 s) and the capability for sustained power generation, up to 8-10 years when derated to I sp about 8000 s. The goal of this paper is to show that current or near term NEP technology enables missions far beyond our immediate interplanetary backyard. In fact, by extending the semi-analytical approach used by Stuhlinger, with reasonable ratios apower/mass of the propulsion system (i.e., 0.1-0.4 kW/kg), missions to the Kuiper Belt (40 AU and beyond) and even the so-called FOCAL mission (at 540 AU) become feasible with an attractive payload fraction and in times of order 10-15 years. Further results regarding missions to Sedna's perihelion/aphelion, and to Oort's cloud will also be presented, showing the constraints affecting their feasibility and mass budget.

2009

While numerous scientifically compelling missions have visited the outer solar system during the past four decades, the science return has been limited partly by contemporary power and propulsion technologies that limit a spacecraft’s ability to carry heavy or high power demand payloads to its destination in a timely manner. Recent studies have endorsed radioisotope electric propulsion (REP) as a strong candidate for enhancing those capabilities. REP mission possibilities include Cassini level science at Neptune or Dawn-like coverage of a Kuiper Belt Object (KBO). This report will discuss the science benefits associated with the use of REP, a trade space analysis of mission architectures, and case studies of REP missions to regions beyond Saturn, with specific distinction to giant planet and small body targets. In addition to these, necessary REP flight qualification developments will be outlined.

6th International Energy Conversion Engineering Conference (IECEC), 2008

Acta Astronautica, 2010

Studies over the last decade have shown radioisotope-based nuclear electric propulsion to be enhancing and, in some cases, enabling for many potential robotic science missions. Also known as radioisotope electric propulsion (REP), the technology offers the performance advantages of traditional reactor-powered electric propulsion (i.e., high specific impulse propulsion at large distances from the Sun), but with much smaller, affordable spacecraft. Future use of REP requires development of radioisotope power sources with system specific powers well above that of current systems. The US Department of Energy and NASA have developed an advanced Stirling radioisotope generator (ASRG) engineering unit, which was subjected to rigorous flight qualification-level tests in 2008, and began extended lifetime testing later that year. This advancement, along with recent work on small ion thrusters and life extension technology for Hall thrusters, could enable missions using REP sometime during the next decade.

National Aeronautics and …, 2005

2010