Archive for January, 2007

Cassini Extended Mission Tour

Wednesday, January 31st, 2007

This week the Cassini Project Science Group (PSG) is meeting at JPL to decide on a two-year “tour” (the trajectory to be flown by the Cassini spacecraft) for the extended mission, affectionately known as the “XM”. The task is not small because the Cassini XM is planned to operate in the same mode as the nominal mission, which means that all of Cassini’s five main science objectives (Saturn, Titan, icy satellites, rings, and the magnetosphere) continue to get equal weight for the XM. Thus there are five competing interests for the geometry of Cassini’s XM tour. While the interests of one group are not necessarily in conflict with those of others, in general it is difficult to accommodate all of the top priorities of each group. Time taken for close flybys of an icy moon, for example, means less time to get the spacecraft in position to observe the effects of the changing season on Saturn’s rings. The JPL tour designers have done a terrific job of coming up with a dozen or so excellent tour candidates, so I’m confident that the various science groups will be satisfied with the tour we select by the end of the week.

In my science discipline (rings) one of the key goals for the XM is to see how the rings behave at Saturn’s equinox, in mid-2009. Saturn’s seasons are about 7 years long, so one might expect very gradual changes in response to a change in season. However, since the rings are a plane, there is a sudden transition from one season (Sun shining on the south face of the rings, currently) to the next season (Sun shining on the north face of the rings). The CIRS instrument measures the temperatures of the ring particles, so this one change-of-season event is an opportunity to see the temperature change of ring particles that may have spent years with only one face in sunlight. These observations in the extended mission will tell us about the rotation of the particles and how they move relative to their neighbors in the rings. That’s just one of many examples of unique science opportunities in the Cassini extended mission.

Blood Diamond

Sunday, January 28th, 2007

This powerful movie puts the brutality and chaos of civil war in Africa in the viewer’s face in an uncompromising and unrelenting way. Leonardo DiCaprio gives an excellent performance as a Danny Archer, a diamond smuggler working the diamond black market from war-torn Sierra Leone where rebels run slave diamond mines to finance their war against the government. Djimon Hounsou also delivers a moving performance as Solomon Vandy, a fisherman whose family is torn apart by the marauding rebel gangs. He finds a large diamond in the mine and hides it before ending up in prison with Archer who immediately sees in Vandy a ticket out of Africa.

Vandy’s sole concern is to find his family, a wife and two young daughters who are refugees, and his son who is abducted and brainwashed by the rebels. With the help of Maddy Bowen (Jennifer Connelly) a journalist investigating the illegal diamond trade, Vandy and Archer form an uneasy alliance to find Vandy’s family and get the diamond to Archer who can turn it into cash.

The movie packs a tremendous amount into its 2 hours and 20 minutes, but it never feels bloated. We see the devastation of civil war and the brutal guerrilla war tactics of marauding youths. It is gut-wrenching, and unflinchingly realistic. We also see the interconnection of the global diamond trade with regional conflicts, and the need for the diamond cartels to control the supply and keep diamond prices high. And we see a broad portrait of conflict in Africa through the life of Archer as a mercenary soldier. It is a powerful and affecting movie.

Sierra Leone is now peacefully and legally exporting diamonds which account for about one-third of its hard currency exports. While that tiny country is at peace, the brutality of the civil war depicted in the movie is a painful but necessary reminder of other conflicts in Africa, such as the Sudan and Congo.

Oscar Nom Not Comprehensible

Friday, January 26th, 2007

I wrote a mixed review of Babel here when I saw it, but now that it has won a Golden Globe for Best Drama and is nominated for a Best Picture Academy Award, I cannot resist revisiting this movie and why I am disappointed that it got a Best Picture nomination. First, though, I want to recognize what I thought was well done in this movie. The acting was convincing and compelling across the board. The individual scenes were well-written and well-directed. It is the implausibility of two of the three individual stories (and the meaningless way that the stories are connected to each other) that I find maddening.

Spoiler alert if you have not seen “Babel” and want to see it.

One story concerns a deaf Japanese high school girl (played by Rinko Kikuchi) whose mother is dead and who feels disconnected from the world. She searches for physical love to help her cope with her loneliness. This story stands on its own with no problems.

The second story concerns the accidental shooting of Susan (played by Cate Blanchett) traveling in Morocco with her husband Richard (played by Brad Pitt). Stuck in a rural area without access to modern medical facilities, they wait it out while the incident is blown up into a terrorist incident and geopolitical concerns interfere with the arrival of an evacuation. I found the set-up of this story to be implausible, and implausible for no good reason. Susan is shot not so much by accident after all. Two young goat-herders are debating the range of their new rifle and decide to see if it can actually hit that tour bus driving down the road. Of course, it can. These kids have no hatred or fear of foreigners, and while perhaps young and foolish, showed no signs of being so unbelievably stupid that they would actually try to shoot another person to see if a gun had sufficient range to do so. The story of the stuck couple doesn’t have any more complexity than the story of a backpacking accident or any other mishap that lands someone in a medical bind far from help.

But the story that really irritates me in this movie is that of Amelia (Adriana Barraza), the live-in caretaker of Richard and Susan’s two young kids back in California. Barraza, like the other actors, delivers a fine performance. But the plot has her take these two kids to Mexico, without written consent from their parents, and then return over the border in the middle of the night, even though she is an illegal alien and the kids’ parents are obviously wealthy and there would be dozens of other options for her. She wants to get to her son’s wedding, which is totally understandable. The problem is that Richard and Susan are stuck in Morocco dealing with the aftermath of Susan’s shooting, which the entire world has heard about on the news. But, Richard tells her she’ll just have to miss the wedding, there are no other options. He doesn’t tell her, “call our friends the Johnsons, or the Joneses or the Smiths or the babysitters”. She goes to a couple of her friends’ to see if they can watch the kids for the day, but no luck. I’m sorry, but there is just no way that there wouldn’t be the entire wealthy-friends network of Richard and Susan on the doorstep looking to see what they could do for those kids. It’s international news that Richard and Susan are in Morocco with a gunshot wound. There is no way she couldn’t drop those kids at friends of the parents for the day so she could go to the wedding. But let’s grant that particular liberty with reality and assume she does have to take them with her to Mexico. What does she expect to happen as an illegal immigrant, crossing the border with two kids that are obviously not her own? Then, on their crazy return to the States, the young driver successfully eludes the pursuing border patrol by driving off into the brush, but rather than just wait there a bit and continue on their merry way, he dumps Amelia and the kids so that he can “lose” the border patrol. He just did lose them! How is driving out on the road so that he can be found again going to help anything? This series of unbelievable events is what sets up what is supposed to be the most emotionally heart-wrenching aspect of the movie, with the near-death of the kids in the desert and the deportation of the woman who virtually raised them. But I found the situation they put themselves in so impossible to believe that I could not connect with it emotionally at all.

That gun used to shoot Susan? Turns out the Japanese girl’s father gave it to a guide in Morocco on a hunting trip. That adds absolutely nothing to either story. The link between Susan and Richard and the kids in the desert only makes the kids’ story less plausible by putting them more in the public spotlight before the ill-advised cross-border trek. And the title “Babel”, together with the publicity campaign that promised a movie exploring the confusion due to our different languages and cultures, actually has nothing to do with any of the three dramas in the movie. No problem in the movie is exacerbated by mis-communication. People are able to make themselves understood quite well. They just make unbelievably stupid decisions.

Home Computer Prediction from 1954

Thursday, January 25th, 2007

Here’s an image from 1954 Popular Science that shows a RAND corporation forecast for what a personal computer might look like in 2004. I love the caption stating that teletype and FORTRAN will make it easy to use. I also love the giant steering wheel. I want one.

Picture of predicted home computer from 1954

I posted this without checking the authenticity, and according to Bruce (see comment), it is a hoax.

Power Companies Endorse Carbon Limits

Sunday, January 21st, 2007

For the latest sign of the apocalypse, a consortium of power companies is actually calling for curbs on carbon emission absent any federal regulatory requirement to do so. Can our government really be that so retarded in addressing CO2 emissions that even the power companies think it’s gone too far? Not entirely. As reported in this article in the New York Times, the likely explanation is that they are trying to head off even more stringent requirements that might be in the offing after the 2008 elections. Said Peter Darbee, Chief Executive and PG&E in California, “a future political climate, after 2008, might produce solutions less sensitive to the needs of business.” The proposed carbon emission limit would see emissions drop below current levels in ten years. It’s a start. Let’s see if the government has the ability to act on this issue in a timely way.

Rising Sea Levels

Thursday, January 18th, 2007

How long before our new home in Orlando is beachfront property? How much longer before it’s submerged. I don’t know the exact altitude in Orlando, but it’s roughly 20 feet. If all the ice on Greenland melts it will raise sea level by 23 feet. There are no accurate models for how fast that might happen, but melting ice from Greenland is now the single largest contributor to rising sea levels. If you want to help preserve the future value of our near-sea-level home, check out carbonfund.org. It might help out the polar bears and the hundreds of millions of people who live within a few feet of sea level around the world too.

NASA’s New Year: Continuing Resolution

Wednesday, January 17th, 2007

One of the consequences of the last congress’s inability to do anything is that NASA is operating in fiscal year 2007 under a continuing resolution. This means that it is able to spend on each program the lesser of what it spent last year or what it proposed to spend this year. With costs ramping up to develop the Orion vehicle and the Ares launch vehicles, and with the so-called Vision for Space Exploration the top priority of the agency, money for those programs will now have to come from other programs. NASA’s earth science programs, already hurting, may well get additional cuts. NASA was looking at increase of more than half a billion dollars, so that’s how much has to be recouped from other programs to cover the Vision developments. I don’t know if this will have any ramifications for the approval of Cassini’s extended mission or not, but I’ve already heard rumors about cancellations of atmospheric science programs.

Cassini: Over the Top

Tuesday, January 16th, 2007

This month Cassini passes the half-way mark of the “Titan 180 Transfer” portion of its four year nominal tour at Saturn. Because Cassini is a do-it-all mission with a dozen instruments on board, it has a broad set of goals that require a wide range of viewing geometries. The most obvious set of conflicting goals is that to study Saturn’s atmosphere equatorial orbits are best because then the rings, only a few tens of meters thick, virtually disappear and do not obstruct views of the planet, while on the other side, ring science prefers highly inclined orbits so that the rings can be easily seen at high resolution. The fields and particles instruments are there to sample the three-dimensional magnetosphere on all sides of Saturn relative to the Sun. Studies of icy satellites generally require equatorial orbits, while studies of Saturn’s aurora near the poles require inclined orbits. So Cassini has literally been flying around all over the place for the 2.5 years it’s been in orbit at Saturn.

Top down view of Cassini's orbital tour
This cartoon shows Cassini’s trajectory around Saturn in the 4 year nominal mission. Saturn is the small yellow circle in the center, surrounded by a slightly larger circle representing the main rings. The two white dotted lines show the orbits of Titan (inner) and Iapetus. The different colors represent different phases of the tour defined by geometry of the orbits. The initial orbits are depicted in white.

Side view of Cassini's orbital tour
The side view shows that some orbits (such as the green phase, completed in mid-2006) are equatorial allowing unobstructed views of Saturn and frequent flybys of icy moons which orbit Saturn in its equatorial plane. Cassini is currently midway through the Titan-180 transfer orbits (blue).

During the tour design process in the late 90’s and early 00’s the clever folks at JPL hit upon an efficient mechanism to cover a lot of different geometries quickly: the Titan-180 transfer (now known as a “pi transfer” during extended mission discussions). Titan’s large size makes it the most effective satellite of Saturn to provide gravitational assists to Cassini and allow it to go onto a very different orbit of Saturn without using much fuel. The same process was used to accelerate Cassini to Saturn in the first place and is currently being used to nudge New Horizons on course to Pluto with a Jupiter flyby. Notice in the pictures above how Cassini’s orbit crosses Saturn’s equatorial plane at or near the orbit of Titan (inner dotted circle). Each Titan flyby allows the mission team to send Cassini onto a different orbit around Saturn. We are now roughly halfway through the Titan-180 transfer (the blue orbits above), so the inclination of Cassini’s orbit is decreasing toward the equator which it will reach this summer. The Titan-180 transfer changes the orientation of Cassini’s orbit, allowing magnetospheric studies to explore a large fraction of Saturn’s magnetosphere. The “transfer” of the title refers to flybys of Titan switching by 180 degrees (or pi radians) from inbound (flying by Titan as Cassini is heading in toward Saturn) to outbound (flying by Titan as Cassini is headed away from Saturn) or vice versa.

The final orbital phase for Cassini’s nominal mission (represented in red above) is a series of small, rapid orbits with increasing inclination. Both the Titan-180 and the final so-called “high inclination sequence” are particularly good for ring science, as well as polar atmospheric studies and magnetospheric studies. There is some exciting icy moon science in there as well, as a close (25 km!) flyby of Enceladus is anticipated for the high inclination sequence, giving us another close look at those intriguing geysers.

Pluto via Jupiter

Saturday, January 13th, 2007

The New Horizons spacecraft is on its way to Pluto and has begun a leisurely encounter with the planet Jupiter that will alter the trajectory of the spacecraft to put it on course for its Pluto encounter in July 2015. The New Horizons team will have an opportunity to exercise their instruments as well as their procedures while taking some useful scientific data on the Jovian system. The reason for the flyby, however, is not scientific, but energetic. In order to get to Pluto, whose orbit is tilted 17 degrees to the orbit of the Earth which means that with the exception of the two times each Pluto orbit that it is crossing the Earth’s orbit, Pluto is either North or South of the Earth’s orbit. The Earth’s orbit matters because that’s where all spacecraft leaving Earth start out. Relative to the Sun, New Horizons, like all other interplanetary spacecraft, starts off moving with the Earth’s velocity around the Sun, plus the extra little bit that the rocket provides it. It takes a lot of energy to things moving in a different orbital plane, and this is where Jupiter can be so helpful.

Jupiter’s orbit is tilted less than 2 degrees relative to the Earth’s, so it’s fairly easy to get there. All you need is enough energy to get 5.2 AU from the Sun, where the Earth, by definition, is on average 1 AU from the Sun. New Horizons will fly by Jupiter in such a way that Jupiter’s gravity will deflect it toward Pluto. No extra energy is required because New Horizons will steal some of Jupiter’s energy. Jupiter can spare it, because while New Horizons will get a big change in its velocity, Jupiter’s velocity change will be smaller by the ratio of the mass of the New Horizons spacecraft to the mass of Jupiter, and that means about 4 million billion billion times less (or 4*10^24, or 4,000,000,000,000,000,000,000,000).

Information on New Horizons’ flyby of Jupiter can be found here. Closest approach is at the end of February, and observations of the giant planet continue from now until the end of June.

Children of Men

Thursday, January 11th, 2007

It seems there’s been a rash of English post-apocalyptic movies lately: 28 Days Later, V for Vendetta, and now Children of Men, in which the form of the apocalypse is the sudden and complete infertility of the human species. Set in England 18 years after the last human birth, the movie portrays a glum and depressing society in which people have a package from “Quietus” at home that lets them decide when to check out of the terminal human condition. The English, with a stiff upper lip, are apparently faring better than the rest of the world which has collapsed into chaos. Determined to hang on until the bitter end, or until a miracle occurs, England hunts down and deports all immigrants who have fled to the country from the mess outside. Hope for a miracle rests with “The Human Project”, a group of doctors working to cure the infertility problem in some peaceful, isolated location. The Azores are mentioned, but most people don’t even believe the project is real.

Set against this hopeless backdrop, the movie follows the efforts of Julian (Julianne Moore) and a team of pro-immigrant rebels who have roped Julian’s ex-husband Theo (Clive Owen) into getting a pregnant woman (Kee, played by Claire-Hope Ashity) to the coast where they hope she will be picked up by a Human Project boat. There’s not much sense of hope in this movie, yet I found myself very much hoping for Kee to make it. Her journey is treacherous not because people want to kill a pregnant woman, but because the environment is the dangerous near-chaos of the fringes of a police state. The movie satisfactorily addresses the obvious question of why she doesn’t just see some government doctors in England. England, although it bravely “soldiers on”, to quote a billboard in the movie, is too far gone to be a safe or helpful place for what is perhaps humanity’s last best hope.

The movie poses an interesting and different hypothetical situation that creates some eerie images. Schools, no longer necessary, decay into ruin. People, still healthy, go about their business, but all are wondering what is the point if not only civilization, but the species itself, will no longer exist in 40 or 50 years. Children, it is clear, keep us all going.