A)Laser radar illuminates the way to deep space
Lidar test image
22 February 2012
This car was not snapped with a camera but scanned by a 3D imaging lidar, the laser equivalent of radar. ESA is developing the sensor as a navigation aid for exploring deep space.
Lidar stands for ‘light detection and ranging’, with a pulsed laser beam scanning targets by measuring the time it takes for the light to bounce back.
ABSL prototype lidar
Laser ranging is already used for rendezvous and docking in orbit. When ESA’s ATV cargo ferry docks with the International Space Station it bounces laser beams off reflectors on the orbital outpost to judge the distance to within a couple of centimetres.
For missions deeper into our Solar System, ESA hopes to use 3D imaging lidar to build up a complete picture of targets such as a boulder-strewn surface.
This would be like a stereoscopic imager but it would also work in total darkness or blinding sunlight.
ATV uses lasers for docking
“The first is for the guidance, navigation and control of planetary landers, in particular in selecting a safe landing site.
“The second is for steering rovers on planetary surfaces, and the third is for docking in planetary orbit. That would be essential for the proposed Mars Sample Return Mission, for example, when the ascent module carrying material off the martian surface will have to be tracked and captured by its mother craft waiting in orbit.
Lidar test 5km across the Saale Valley
“The challenge is to produce a new class of imaging lidar, much smaller and needing less power.”
Reflecting the technical difficulties involved, separate designs were developed in parallel by two consortia, one led by Jena-Optronik in Jena, Germany and the other by ABSL in Culham, UK.
The shoebox-sized imaging lidars rely on a steerable scan mirror that flicks the laser beam across the target, with a highly sensitive light detector capable of measuring the returning beams from up to several kilometres away.
Jena-Optronik prototype lidar
The two designs aim at different guidance and navigation applications. The German-led unit demonstrates a future rendezvous sensor, while the British-led design is intended to help a lander touch down safely on a planet, detecting and avoiding hazards.
ESA Lunar Lander
Building on this progress, a landing lidar is now being designed for ESA’s Lunar Lander, planned to touch down at the lunar south pole in 2019.
The engineers are also looking at ways of making the lidars even smaller perhaps by using new types of detectors and micro-mechanical optical mirrors.
“It is expected that we can reduce the mass and power consumptions of current commercial imaging lidar systems by at least 70%,” Joao concludes.
B)Various Thoughts on the Flagship Mission
One of the readers of this blog sent me a note asking why it will take almost 11 years to launch the just selected Jupiter Europa Orbiter (JEO) mission. I have not followed all the ins and outs of this, but I’ll share what I think I understand. Normally, a new mission takes approximately four years to develop after it receives a new mission start. Prior to that, it is common to spend some time in pre-start mission development. If money was no issue, it would be reasonable to expect that JEO would launch in the mid 2010s. A 2007 study of a Europa Explorer (the predecessor concept to JEO) presumed the launch would be in 2015. If you look at NASA’s expectation for launching the Flagship mission a year ago, the target date was 2016-2017.
After that time, NASA slipped the launch date to around 2020. The stated reason was to align NASA’s schedule with ESA’s schedule, which could not fit a launch before that into its funding profile. I suspect that the looming cost overruns of the Mars Science Laboratory might have made the delay on NASA’s side inevitable. In any case, now that the MSL cost overrun is on the books, funding for preliminary studies of JEO are slim for the next couple of years. So, we have a 5 year push out in expected launch date over the last two years.
Could NASA pull in the JEO schedule if ESA does not select its potential contribution, the Jupiter Ganymede Orbiter (JGO) in 2011 to fly? Potentially. However, I suspect that it will take awhile for NASA to work through the problems created by the MSL slip and the earliest launch probably would be in the 2018 timeframe at best. Without access to NASA’s funding expectations, this is speculation, however.
On another topic, what if ESA doesn’t select JGO? How might the JEO mission change? The major loss from JGO would be the intense set of flybys of Callisto and the study of Ganymede from orbit about that moon. JEO has an excellent set of instruments for studying the moons of Jupiter during flybys. In fact, a series of flybys are planned of all four Galilean moons. JEO cannot carry enough fuel to orbit Ganymede as well as Europa, so the study of Ganymede from an orbiter would be lost. On the other hand, JEO could delay its orbit insertion at Europa to allow more time for more flybys of other moons. (More flybys than the planned handful at Io are probably out because of radiation issues.) JGO would spend approximately a year conducting 19 flybys of Callisto. JEO could spend an additional year carrying out flybys of either Callisto, Ganymede, or both. If such a plan was implemented, I would expect Ganymede to receive the lion’s share of additional study. The scientific community has prioritized further study of Ganymede over Callisto.
Jason Perry has posted another excellent analysis on his website (see C)about what the selection of JEO with its planned Io flybys would mean for the proposed Io Volcano Observer (IVO). He correctly points out that IVO would conduct more flybys (at least 7, probably 14, and possibly even more) compared to JEO’s 4. The flyby geometry selected for IVO would also be more optimised than JEO would be have. (JEO will use the Io flybys in part ot set up later encounters with other moons and hence is constrained in the selection of flyby geometries.) Jason points out that the proposed IVO instrumentation would be more optimized for Io studies than the proposed JEO instrumentation would be for Io. However, this may not remain the case. The proposed instrumentation for JEO is a strawman to show capabilities and allow conceptual design of the orbiter. The actual instruments will be selected from proposals submitted by scientists in several years time. It is very possible that the winning instruments will be tuned to do better at Io than the current strawman payload would.
Two missions to the Jovian system are on the official list for the next New Frontiers mission ($650M). One is an Io observer and the other a Ganymede observer. The selection of JEO and possibly JGO would seem to make the selection of the Ganymede observer unlikely in my opinion. JGO is the Ganymede observer done right. The Io observer faces hurdles in terms of being selected, too. As Jason points out, there are still valid reasons to fly IVO. The science it would return over what JEO will and may return has to be better (and at lower risk) than the science from all other proposed missions. That may not be possible. I would love to see IVO fly, but I have strong doubts that it will. (Note: IVO is a Discovery mission ($450M) and not a New Frontiers mission. However, I think this reasoning still applies.)
As my final thoughts, I’ll speculate on what may be a crowded place the Jovian system could be in the 2020s. This year (2009) is the year of the moon with Chinese, Japanese, Indian missions there now. ESA just finished a lunar mission and NASA will launch its soon (with more to come). The 2020s could be the decade of Jupiter. NASA and ESA may have orbiters exploring the moons and observing Jupiter itself. The Japanese space agency, JAXA, is considering an orbiter to explore the Jovian magnetosphere. Russia is considering a lander for Europa. Other nations likely will have the capability to send missions to Jupiter. What might those craft do? Additional craft to explore the magnetosphere would be useful. A craft in polar orbit around Jupiter could study the polar regions of Jupiter, keep an eye on Io, and explore another corner of the magnetosphere.
Unless new news comes out about JEO, I’ll take a break from this topic for a bit. In the next few weeks, the NASA FY10 budget will be released and will show the new administration’s priorities for planetary exploration. There will be meetings of NASA’s scientific advisory boards for Venus where a Flagship mission will be proposed, the Outer Planets where we may learn more about the issues that led the selection of Europa Jupiter over Titan Saturn, and Mars where re planning the exploration roadmap for the next decade will begin. I also want to complete the discussion of concepts for missions for the next New Frontiers mission selection.
SOURCE http://futureplanets.blogspot.com FEB/2009
c)How EJSM affects the Io Volcano Observer
With a mission now planned for the Jupiter system in the 2020s, how will the Io Volcano Observer proposal be affected? Would a dedicated Io mission even be necessary?
The Io Volcano Observer and the Jupiter Europa Orbiter would conduct complimentary science. Both spacecraft have high-resolution cameras capable to studying Io’s surface in fine detail during flybys as well as monitoring Io’s global volcanic activity from a distance. Both can conduct mass spectroscopy of Io’s atmosphere and plumes as well as observe Io’s thermal inertia. The Jupiter Europa Orbiter would be capable of acquiring observations not currently in IVO’s baseline payload such as near-infrared spectroscopy, ground-penetrating radar, laser altimetry, and particle and plasma analysis. So seemingly, the Io Volcano Observer would not be necessary. Not so fast.
The Jupiter Europa Orbiter’s instruments are designed to study Europa, with bandpasses of the various instruments and their functionality driven by that requirement. Studying the other bodies in the Jupiter system, while a level 1 science requirement, really is just gravy for the mission. JEO’s unique instrumentation, such as the Ground-penetrating radar, can answer quite a few questions that IVO can’t. However, the design of the payload for IVO has been defined to specifically answer questions at Io. For example, the camera on IVO would be capable of observing volcanic activity with multiple filters with less than 0.1 seconds between color frames. This allows fairly accurate measurement of the lava temperatures at Io’s volcanoes. This can constrain the amount of partial melting in the mantle needed to support the eruption temperature observed. The band passes on the Thermal Mapper, rather than being selected to search for warm spots on an icy world, will be selected to explore different volcanic processes on Io of different ages as well as looking at the silicate composition of these flows.
Also, don’t forget that IVO will perform at least seven Io flybys during its 1.5-year primary mission (starting in early 2021), three more than the encounters planned for JEO. In addition, IVO has enough margin in its radiation shield to support seven more encounters, which could be spaced out by as much one year apart to help study the long-term life time of IVO’s power source, the two Advanced Sterling Radioisotope Generators (ASRGs). This extended mission could help fill the gap between IVO’s primary mission which ends in late 2022 and JEO’s arrival in late 2025. This provides the potential for spacecraft monitoring of Io covering almost eight years, similar to Galileo’s time at Jupiter.
While the Jupiter Europa Orbiter will perform quite a bit of science at Io, since the instruments are not optimized for Io science, there is still a need for a dedicated mission like Io Volcano Observer. Potentially JEO could allow IVO to trim some costs by reducing some of the redundancy, like the magnetometer instrument. However, the priority for an Io mission may go down in comparison to other potential Discovery-class missions with the EJSM arrive only a five years later than IVO.
SOURCE http://www.gishbartimes.org FEB/09