Waiting for radar

The uncertainties about the Marsis radar on Mars Express have not gone away. As I mentioned back here, doubts were raised this spring about the safety of deploying the radar's antennae, because it seemed possible that they would snap back and hit the spacecraft itself, which would probably be bad and possibly catastrophic. According to the ESA website, analysis of the problem has yet to provide an all clear, and so deployment is being further delayed, on the basis that it's better to do without Marsis data -- which might conceivably provide evidence of liquid water in deep aquifers -- than to endanger the whole mission. The system won't now be deployed until October, if then. There's a little more discussion of the ESA statement in a report at BBC Online.

If the risks of deployment look too great to face this year, though, that may change with time. There must surely come a point at which the trade-off between preserving the spacecraft's remaining life at all costs and getting data from the radar starts to tip in the radar's favour. Once the Omega spectrometer and the HRSC camera have covered most of the planet's surface, and when the atmospheric instruments have been able to capture a full Mars year of readings, I suspect the case for risking the remainder of the mission in the hope of getting some qualitatively new data will seem a good bit stronger. That would be some time in early 2006. If by that time there's a consensus on a specific source region for the methane, the case for deployment would, I suspect, be seen as stronger still.

Another issue that might conceivably factor into the decision would be the risk of getting scooped. In March 2006 the Sharad radar will arrive on board the Mars Reconnaissance Orbiter; its antenna will be deployed about six months later, after aerobraking. Sharad is designed to make a different sort of measurement; it confines itself to the shallow sub-surface and has much higher resolution. It's not in a position to discover big deep aquifers. But it's conceivable that Sharad might pick up evidence of shallow aquifers in some places, if there are any such aquifers there. And a discovery of liquid water by NASA would overshadow any further such discovery by ESA.

So a sense of competition might provide a marginal extra incentive for deploying Marsis before MRO gets into its science orbit in late 2006. But there might also be a case for waiting a little longer. The antenna deployment mechanisms for the two spacecraft are similar and designed by the same company -- it was work on the Sharad deployment that raised the possibility that there could be problems with Marsis. Data from a successful Sharad deployment might conceivably change the analysis-based picture of the risks of deploying Marsis. If Sharad's deployment can be seen as a test run for Marsis, it might be a good idea to let Sharad go first.

If deployment doesn't go ahead this year, the decision about what to do in a few years' time will be a very tricky one. Some Mars Express scientists will want to preserve the integrity of the spacecraft -- and of their own data streams -- come what may. Others will want to push for exploring the subsurface, even if that involves risks. And it's possible the risks aren't evenly distributed -- what if analysis shows deployment as being unlikely to hurt the spacecraft as a whole, but quite likely to poke out the eye of one of the other instruments...

Let's hope there'll be a good, open debate about this. But since we're dealing with ESA, let's not hold our breaths.

PS: for those interested, I've added some links to good obits to the end of the Tommy Gold past

Comments

[Andrew Gray]

With regards to delaying Marsis deployment until Sharad turns up on MRO, this allows for the interesting potential of the two instruments operating from different spacecraft at the same time. I can't offhand see any reason that data gathered in both "areas" simultaneously is any more interesting than one set, then the other, a year or so apart... but there might be something that I'm not noticing there, it's more than possible. (it's not, by any stretch of the imagination, a field I know anything about, but...)

[Lance Niederhaus]

Here is an interesting article about the supposed water cycle on Mars.

Martian Obliquity Keeps Vast Glacial Cycles Moving
http://www.spacedaily.com/news/mars-water-science-04l.html

Not being any sort of an expert myself, I would appreciate hearing your collective comments regarding the implications for this.
Thank you,
Lance

btw- Oliver Morton's book "Mapping Mars" is captivating, interesting and easy to understand for us non-scientists. Hope you write another one soon...

[Lance Niederhaus]

I was certain that the article about the martian water cycle I linked in my last post would have piqued the interest of some of the regulars on this blog, especially with the implications of how important and unfortunate it is that the marsis radar arm deployment has been indefinitely delayed. I would be extremely interested (and grateful) to see your comments and opinions on this.

Waiting for Reply,
Lance

[Alex R. Blackwell]

Larry, I agree that the delayed deployment, if ever, of Mars Express MARSIS has been a severe blow. It is clear that subsurface studies of Mars, especially in the near-polar regions, are the next logical step in trying to untangle the Mars water story. The Levrard et al. and Laskar et al. papers are interesting reads and only highlight this huge gap in our current knowledge.

[Joj Reuben]

One thing that might work in favour of the MARSIS deployment (despite the rumoured risks) is that Omega - the IR spectrometer - has a life limited cooler. If that does eventually fail (there is no backup on-board), then the small(?) risk of losing the entire mission might become one ESA is willing to take.
Although complementary data-sets from MARSIS and SHARAD might be useful, presumably the results are not likely to be time-dependant (at least over the scale of the mission lifetime). Some of the same teams are working on both so perhaps there is a motivation not to operate both simultaneously? From reading the specs the instruments do not overlap in the data they will collect (maximum 1km vs 50km depth) so perhaps the deployment of SHARAD in 2006 does not really affect the validity, relevance or timeliness of data from MARSIS?

[Bruce Moomaw]

New Scientist now reports ( http://www.newscientist.com/news/news.jsp?id=ns99996509 ) that the decision has been made to deploy MARSIS next March. The latest ground tests are encouraging -- even in the worst case, the antennaas are unlikely to backlash with more than 1 kg of force -- but they're still erring on the side of caution.

[Andre van Hooren]

The article in the New Scientist doesn't say the decision has been made to deploy the radar. It says it will not be before March (if at all). In fact, all the computer simulations still have to be done.
The chief scientist William Johnson says : "But probably isn't good enough."
That does not bear very well. In fact, with Mars Reconnaissance Orbiter so close, competition between the Europeans and the Americans may play a role. The Americans are running the Marsis radar, and Jeff Plaut is both on the Marsis and the Sharad team. The European scientist on Marsis, Piero Biocca, works at Alenia Spazio, the maker of the Sharad instrument. Of course, the instruments are different, and everybody wants both of them to work well, but I think the Marsis team does not have the burning desire to be the first with Marsis. Johnson is slowly preparing us for waiting till MRO arrives, especially since the experiments have left some doubt over its safety.

[Alex R. Blackwell]

Andre van Hooren wrote:

The Americans are running the Marsis radar, and Jeff Plaut is both on the Marsis and the Sharad team. The European scientist on Marsis, Piero Biocca, works at Alenia Spazio, the maker of the Sharad instrument.

Alex Blackwell writes:

Since Giovanni Picardi of ‘La Sapienza’ University of Rome is the MARSIS Principal Investigator (PI), I'm not sure I would agree with your flat assertion that "The Americans are running the [MARSIS] radar." To be sure, Jeff Plaut is the MARSIS Co-PI, which ensure the U.S. (read JPL) has a prominent role in the instrument's operations. That said, however, the final decision on MARSIS deployment will be made by ESA and the Mars Express managers, not "the Americans."

[Bruce Moomaw]

It's most accurate to say that the New Scientist article indicates that MARSIS probably will be deployed next March -- the computer modelling is just an extension of the already-encouraging results from the tests. Still, I wouldn't be shocked if they decided to hold off until Mars Express has made one full Mars year of observations, in early 2006. I WILL be shocked if they decide never to risk deploying it at all.

[J. Reuben]

The article in New Scientist quotes Jeff Plaut and Will Johnson as stating that the final decision to deploy rests ultimately with ESA. This makes sense since it concerns the safety of an ESA spacecraft. JPL/Astro may have built the antenna but all decisions on spacecraft instruments ultimately rest with the PI, in this case G.Picardi (Rome).
With the pericenter latitude currently over the equator and climbing to reach the North Polar region in March 2005, combined with the prerequisite lack of daylight during MARSIS commissioning observations at that time, this does make for a perfect "window", which would not be repeated for at least 18 months. The observations are otherwise affected by the ionosphere (when illuminated by the Sun), and reliable calibrated data on where the water is might then be a long time coming?
Joj