It's summer time, which means that news is slow and I'm spending over half my time doing field work for my research. Anticipating both a slowing of news and limits on my time, I've lined up a series of abstracts and news releases that either update or expand on a future mission proposal. If you assiduously scan the Internet for this type of news, I apologize for the repetition. Otherwise, I hope you find these posts informative. When news does occur, I will report it.
NASA continues to study options for missions for Europa with an update promised for this Fall. The proposals under consideration would use the Stirling-based ASRGs rather than the MMTGs that had been planned for the flagship mission. This probably both reflects the lack of a start of new plutonium production (ASRGs use approximately a quarter the plutonium of the MMTGs for the same power output) and the lower cost of the expected missions (NASA has been reluctant to commit a multi billion dollar mission to the still unflown ASRG technology).
The latest cost projections for the James Webb Space Telescope that will be the successor to the Hubble Telescope are $8B for the hardware and $700M for the first five years of operations after launch. The journal Nature reports that NASA has proposed taking half the money still needed from the science program and half from the rest of NASA's programs. Editorial Thoughts: In the last decade, NASA reduced science spending to fund the manned spaceflight program; if approved this proposal would tax the manned spaceflight program to support science. It's possible that the planetary program would also be reduced to help fund the Webb Telescope. This telescope promises to be a cornerstone mission to understanding the early history of the universe, and while I would hate to see a planetary mission not flown, I'd hate to see this telescope cancelled even more. (For a less optimistic view of NASA's budget problems, check out NASA Watch.)
The White House has ordered all federal agencies, including NASA, to prepare their FY13 budget proposals, which will be submitted to Congress next winter, assuming a 5% cut from this year and identifying an additional 5% cut that could be taken. Editorial Thoughts: I don't know what NASA's planetary budget will be two years from now, except that no further decline than already planned may be good news.
Titan Mare Explorer (TiME): A Discovery Mission to Titan’s Hydrocarbon Lakes
This mission to place a scientific probe to float in a Titan lake has been a popular one with readers (and myself). At the Low Cost Planetary Mission conference a couple of months ago, the current plans were presented. The abstract from that talk is republished with permission.
Abstract. The Titan Mare Explorer (TiME) will land on Ligeia Mare, one of three large methane seas discovered by Cassini in the northern hemisphere of Titan. The seas of Titan provide an opportunity to explore a planetary surface whose chemical constituents are radically different from Earth, with liquid hydrocarbons making up the lakes, rivers, seas, rain and clouds seen by Cassini-Huygens. The seas of Titan are also repositories of organic molecules, chemically generated in the atmosphere above the sea, altered in ways we do not yet know on the surface, then deposited in the polar seas. The seas provide chemical and isotopic clues to: the processes of organic chemical evolution that have gone on for billions of years on Titan; perhaps the original materials from which Titan formed; and a medium within which networks of organic reactions, different from those in the aqueous medium of Earth, proceed toward a threshold that could be considered as life.
The self-contained, ASRG-powered TiME capsule will enter directly into Titan’s atmosphere, to float on the Ligeia sea. It is designed to operate in an almost completely autonomous manner, floating with the wind and waves. The payload consists of just three instruments, focusing on organic chemistry, meteorology, seafloor topography, and sea characteristics. This short, simple, passive mission architecture is key to enabling Titan science within the Discovery program.
The next major step in understanding Titan will be achieved through the two goals of TiME: 1) Understand Titan’s methane cycle through study of a Titan sea, and 2) Investigate the history of Titan and explore the limits of life. The science objectives to support these goals focus on determining the key unknowns for Titan’s seas: their chemistry, meteorology at the sea surface, depth, and sea properties. TiME has a small, high-heritage payload of three instruments: a neutral mass spectrometer, a meteorology and physical properties package, and an imaging system.
The science objectives of TiME are highly responsive to NASA and Discovery program goals and the key themes and science questions in the NRC Decadal Survey for Planetary Science. TiME will directly measure the composition of one of the major organic inventories on Titan, responsive to the ‘Volatiles and Organics: The Stuff of Life’ theme. The noble gas and isotopic inventories to be measured by TiME are highly relevant to the cross-cutting theme of ‘Origin and Evolution of Habitable Worlds’, under ‘What planetary processes are responsible for generating and sustaining habitable worlds?’. TiME will examine the extent to which organic chemistry on Titan has progressed toward or even beyond the threshold of biochemistry, also relevant to the Decadal theme of ‘Origin and Evolution of Habitable Worlds’. The study of the first active liquid cycle on a planet other than Earth, and of Titan’s marine processes are directly relevant to ‘Processes: How Planetary Systems Work’.
TiME will reduce the risk and enhance the science return from future Flagship-class missions by exploring in situ a key component of Titan’s methane cycle, and pathfinding operations in Titan’s extraterrestrial marine environment. Future missions that arrive after Earth has set from view of Titan’s high northern latitudes would need to include a costly relay spacecraft or target the much smaller southern lakes. An opportunity such as that embodied in TiME will not occur again for almost 30 years. In situ exploration of a major sea is the essential next step for advancing our understanding of Titan, provides an unprecedented opportunity to engage the public, and will be a reminder of the excitement inherent in visiting an unexplored and exotic environment for the first time.
Editorial Thoughts: All three Discovery mission finalists (which also include a comet multi-lander and a Mars geophysical station) are compelling, and I hope that each gets to fly. TiME is the only mission, so far as I know, that must be selected in this competition to fly so that it lands when Titan's northern lakes are in view of Earth. Assuming that this mission survives the engineering and programmatic reviews over the next year, my guess is it has a high chance of selection.