Mike Brown's Planets: Hubble

Showing posts with label Hubble. Show all posts

Godspeed

We astronomers like to toy with the ideas of life and of death. We name distant objects after gods of the dead and underworld, like Orcus or Pluto, we eagerly discuss cannibalistic galaxies and gamma ray bursts that would wipe out civilizations for light years in radius. We talk about catastrophic impacts and the possible slow death of the entire universe. But, usually, it is just a vicarious show. Nothing that we study out there in the universe will is likely to actually affect anything down here on earth. Nothing that we do is really a matter of life and death.

Except for this week.

This week, for the sake of astronomy, seven people will strap themselves on to the top of a controlled explosion and launch themselves almost 200,000 stories into the air. If all goes well, they’ll spend nearly two weeks confined to a tiny container holding the only patch of livable space for 400 miles in any direction, before they drop back to earth in a flaming descent that transforms into a supersonic glissade to the ground.

The seven are the astronauts on the final Space Shuttle servicing mission to the Hubble Space Telescope. If they are able to carry out everything on their extensive list, they will leave behind an enormously capable telescope capable of years more of distinguished and fascinating scientific inquiry.

Astronomers the world over will rejoice, but I will rejoice a bit more than average. A year ago, I proposed to the committee in charge of the Hubble Space Telescope that they allow me to spend a significant amount of time on the telescope to use one of the brand-new instruments being put in by the astronomers to study the origin of the Kuiper belt. It was a bit of a long shot, I thought. These committees tend to favor things such as figuring out the origins of distant things, like galaxies, or the universe itself. Our local neighborhood is often overlooked. But the committee liked the idea and now all that stands between me and getting to use this fantastic new instrument in space is the fact that the instrument itself is currently sitting in Florida. At least as of this moment. But come blast-off it and the seven astronauts will be on their way to space.

This moment almost never happened. If I were in charge, it never would.

After the 2003 Space Shuttle Columbia break up over Texas, NASA declared that the only safe way to fly the Space Shuttle was to go to the Space Station where it could be inspected and, if problems were found, astronauts could temporarily stay while repairs or rescues were mounted. But because of their very different orbits, you can’t get to the Space Station if you go to the Space Telescope. Thus, there would be no more flights to the Space Telescope and it would soon plummet to the earth and burn up in the atmosphere.

There was a great outcry. Hubble is invaluable! Hubble is a national treasure! It seemed as if every astronomer out there had stories to tell about why Hubble was spectacular.

I agreed. I had my own stories, even. Many of the fabulous finds about dwarf planets over the past decade have been made by or aided by the Hubble Space Telescope. And there are many many more things that I still want to do with it. And then I said that it was OK to let it die. Hubble had had a spectacular decade and a half, and if it was not safe to refurbish it anymore we astronomers needed to celebrate its legacy, mourn its loss, but accept that it was for the best. This was no longer an abstract matter of galactic life and cosmic death: this was a matter of real life and, quite possibly, death. This actually mattered.

I grew up in Huntsville, Alabama, a thoroughly dedicated space town, and reminders that things do not always go as planned are strewn throughout the city. The high school to which I went was named after Gus Grissom, who died during a pre-launch test of the Apollo 1 mission. Ed White and Roger Chaffee – who died along side Grissom – have their own schools just across town. You can see the Challenger school from the back deck of my parent’s house.

I love space exploration. I love human space exploration. I grew up on it. I wanted to be part of it. I became an astronomer because of it. I understand – I think – the risks, and am even willing to accept them. Sometimes. But not blindly. I feel that many of the astronomers pushing and pushing and pushing to get the Shuttle to fly to the Space Telescope never once thought about the risks, never drove around a town with schools memorializing astronauts who never came home. This actually mattered.

What are the risks of catastrophic failure, as the worst-case scenario is known? I have heard absurdly precise estimates of 1 chance in 187, though I neither know how these numbers are arrived at nor put much faith in them. I do know that this next mission is designated STS-125 – the 125^th Shuttle flight. Two have ended in disaster. That’s 1 in 64. While that’s not quite Russian roulette with a six-shooter and a single bullet, neither is it a short drive to the office in light traffic. It was worth thinking hard about this. This actually mattered.

In the end, the tea leaves were clear from the beginning. The outcry was too loud for the Hubble to be allowed to fall from the sky. The Space Shuttle would go after all.

It’s probably good that I wasn’t in charge. I don’t think I ever want to be in the position of making decisions that could directly lead to someone never coming home to their family again. But someone has to make those decisions. I would have chosen differently, but I understand the choice. The astronauts themselves know what they are getting in to and are itching to go. Who am I to say no? And, since the decision is made and they are indeed going, I’ll be the one watching from down here on earth cheering loudly, remembering the excitement I’ve felt with every blast off I remember from Apollo on. And this time I’ll be cheering even more loudly, thinking about the years of discovery ahead and the origins of the Kuiper belt and things about which I have not even begun to dream.

You will likely not be surprised to learn that I am a non-religious person. I draw my spiritual inspirations from Etruscans and Inuits and small children and the full moon itself. And yet, when searching for the right incantation, the right words of encouragement and amulet against harm, the best one that comes to mind describes something that those seven astronauts will both have in an almost literal sense and certainly need in the intended sense:

Godspeed, STS-125, godspeed.

Nervous gyrations

On Sunday May 11^th, at 6:53 PM, looking from my backyard, the sun will still be appealingly gleaming above the western horizon, with almost an hour to go before it sets. Almost straight overhead the almost-first quarter moon will be waiting to steal the show as soon as the sun is gone. But I won’t be looking at either one. My eyes will be focused just above the eastern horizon where my current favorite outer solar system object – 2003 EL61, better known as Santa – will just be rising. OK, so I won’t see anything but blue sky; even at night Santa is about 10,000 times too faint to see with the naked eye. But I’ll be looking that direction thinking about the fact that at that moment the Hubble Space Telescope will be joining our hunt for moon shadows. On May 11^th and then four other days over the following two week period, the telescope will come around the earth, swing towards Santa, and snap a quartet of pictures to help us determine precisely where the small satellite (aka Blitzen) is.

This is good news! Without the Hubble we feared that it would be another year or two before we figured out the orbit well, and in that time it was quite possible that shadows of Blitzen would no longer be falling on Santa. The case that we made in our emergency plea to use the telescope must have been compelling; within two days of sending in the proposal we had heard back that we had been approved. But there was some bad news, too. Hubble is approaching two decades in space, so things sometimes fail. Visits by the space shuttle continually fix the Hubble back up and add new capabilities, but with the space shuttle fleet itself barely limping along, Hubble has gone without a visit now for more than six years (a new visit is scheduled for late summer). In that time some of its gyroscopes have failed.

Gyroscopes are critical on a spacecraft like the Hubble, because they keep track of which direction is which. They work just like a spinning top works. As long as the top stays spinning fast it stays pointed in the same direction (in the case of a top that would be up); as the spinning slows the top starts to wobble and finally falls down. In space, with no gravity, the top would just keep spinning in whichever direction it was originally pointed. If the spacecraft does some maneuver to point in a different direction, the top still stays fixed pointing in whatever direction it started. Tops – which is all that gyroscopes really are – are great for space, because, with no gravity and no compass, there are not many other ways to figure out which direction you’re pointing.

If the Hubble had no gyroscopes left it couldn’t do anything. Luckily, three still survive. With three gyroscopes you can point anywhere in space at anytime. Wisely, though, the people who run Hubble decided that it was better to keep one in reserve in case one of these last three fails. So Hubble operates with two gyros. With only two you can still point to anywhere in the sky, but not at anytime. And this where the bad news comes in. After about noon on May 24^th Hubble can’t observe Santa again for a few months.

The people at Hubble wanted to know: was it still worth doing the observations? We had to ponder. We think Blitzen takes about 19 days to go around Santa. From May 11^th (which was the soonest we could get on the telescope) until May 24^th is only 13 days. So we won’t see the complete orbit, but we think we’ll see enough to be able to calculate where Blitzen is the rest of the time. “Proceed!” we said.

But then there was worse news. Hubble uses the gyros for course pointing, but for keeping the telescope absolutely still during the course of the observations it also tracks a pair of bright stars close to the target. And, by bad luck, there aren’t enough of them close to Santa. A single star is available up until the 19^th, and then absolutely nothing. We can do the observations, slightly degraded, with a single guide star, but there is nothing to be done after the 19^th. So now we were crammed into May 11^th through the 19^th, an eight day window, when we really had hoped for a full nineteen day window. They asked again: is it still worth it?

By luck, if you only had eight days out of nineteen, these might be precisely the eight days you would want. They are when Blitzen is closest to Santa, which is the part of the orbit we need to know best. But still, it’s going to make our lives even harder than before. Will it still work? We did some quick calculations and decided, once again, we could do it. So we’re on for our eight days in May.

Now I’m nervous. We promised a pretty spectacular result to the people at Hubble. We need to deliver. There is always the chance that the new data will show that the shadows just finished happening and we’re too late. That would be bad luck, but we could at least hold our heads high and say we figured it out, just a little late. No, what makes me nervous is the possibility that we will get the data and still not be able to figure it out. People will say: OK, what’s the answer? And we will have to say. Well, um, we still can’t quite calculate the orbit. We can’t tell you when there will be moon shadows. Wait until next year.

I don’t think this will happen, so mostly it’s just paranoia. And I always have it. Every single evening when I am sitting at big telescope and the sun goes down and the dome shutters open I get similarly nervous. What if we did something wrong and all of our careful calculations about what we are going to look at and what we might discover were wrong? What if we forgot to take something into account? What if there is a better way to be using the telescope? What if…

And then the sky darkens and our first targets appear on the screen and I forget all of the nervousness and worry and get to work.

The same thing will happen, I hope, with this project. I won’t be at the telescope this time. I’ll be sitting at my desk sometime a few days after May 11^th, when the data finally get transmitted and processed and downloaded onto my computer, and I’ll pull up the first image and forget all of the nervousness and worry and get to work.

I'm trying to follow a moon shadow

I wrote a few weeks back about the orderly process of obtaining time on telescopes. Once or twice a year you write a proposal that explains exactly what you want to do with the telescope and why and what you hope to accomplish, and all of the proposals are read by another group of astronomers who pick the ones they think are the best, and they assign them to nights on the telescope. So controlled. So rational.

This annual or biannual cycle is about right for keeping up with new ideas and new discoveries and working on them to the point where you can write something coherent and convincing for a proposal. If proposals were accepted every month instead of every six months, you would have nothing new to write. If they were accepted once every 5 years, you would have new ideas in the interim that there were no ways to explore. I like the system.

But, every once in a while, something happens where you need to be at a telescope right now, and you didn’t realize it in time to have written a proposal six months or a year ago.

Such is the case for me at this very moment.

First, a little history. We discovered the Kuiper belt object 2003 EL61 (which has no real name, only this license plate number; I’ll explain why, and my irritation with the IAU for refusing to allow this object to get a name, in a later posting) back on Dec 28^th, 2004 (with the discovery so close to Christmas and no other name forthcoming, we generally refer to this object as Santa). Within about a month we had discovered that Santa had a moon around it (which we call Rudolph, of course). By mid-summer we had collected enough data to be able to calculate the precise orbit of Rudolph around Santa. We found that Rudolph goes around Santa every 49 days in a nearly circular orbit, and, interestingly, the orbit is currently almost edge on to us. Orbits can be edge on or face on or anywhere in between. Face on means that we are viewing the orbit from above, and we see the moon circling the object. Edge on means that we are viewing the orbit from the side and all we see is the moon going up and down in a line. In between we would go from the circle of face on, through a series of increasingly squashed ellipses, until finally we got to the straight line of edge on. When we looked exceedingly closely at Rudolph we realized that it wasn’t quite perfectly edge on, we could see a tiny little bit of the squashed ellipse.

By the fall of 2005 we realized that something else was going on, too. Santa and Rudolph had another companion. It had been in the data all along, but we hadn’t noticed it at first because it was so much closer and fainter than Rudolph that sometimes the data weren’t good enough to discern it. We call this one Blitzen. Because we couldn’t always see Blitzen we couldn’t actually calculate its orbit around Santa. Complicating matters even more, Blitzen is so close to Rudolph that the extra gravitational pull from Rudolph continuously changes Blitzen’s orbit. Figureing out Blitzen’s orbit was going to be very complicated.

Since then, we have continued to try to see where Blitzen is, but we still have a hard time. In 2006 we got some nice images of Blitzen with the Hubble Space Telescope, but not enough, because Rudolph had already changed the orbit from 2005. In 2007 we tried and tried and tried at the Gemini telescope with only a little success, and, this year, getting a picture of Blitzen was one of our main goals for the laser guide star adaptive optics Keck trip that happened last month. We still lack enough data to figure out the precise orbit, but from the most recent good picture that we got a few weeks back we suddenly realized that the orbit of Blitzen appears to be exactly edge on. We had always known it was close, but we never had good enough data to see precisely how close. Now we think we do.

An orbit that is edge on will not stay that way long. As Santa goes around the sun, our viewing angle of the orbit will change. If it is edge on now, it will slowly move to more face on before moving again to edge on in about 130 years.

While most of the time we don’t care exactly what orientation an orbit is to us, edge on is special. Edge on means that sometimes Blitzen travels directly in front of Santa, and sometimes directly behind. The shadow of Blitzen will at times traverse the face of Santa. All of these things give us the opportunity to learn things about Santa and about Blitzen that we have no other way of knowing. If we can see the shadow hit the face of Santa (by looking for a slight dimming in the overall light from Santa), we will know, much more precisely than any other way possible, where Blitzen is, the size of Santa and Blitzen, how bright Blitzen is, and many other things that we had only dreamed of knowing before. Edge on orbits are fantastic scientific boon!

Even though we think we now have enough data to know that the orbit is edge on, Rudolph still changes Blitzen’s orbit around enough that we still don’t have enough data to calculate the orbit well enough to know when the shadow will transit or when Blitzen will be eclipsed. For that we need more time at the telescope. Usually we would just wait until next year to write another proposal, but it is very likely that by next year the edge on orbit will have opened slightly, and the all of the shadows and eclipses and occultations that have been taking place unobserved will not occur again for 130 years.

What to do? The only sure-fire solution is to use the Hubble Space Telescope. While we could try telescopes here on the ground, the vagaries of weather and the variable quality of the data mean that there is still a pretty good chance that we wouldn’t know the orbit soon enough. The Hubble, however, sitting high above the earth, has no weather to contend with. We know exactly what we are going to get, and we know exactly how good it is going to be. We need Hubble!

But the proposals to use the Hubble were due a month ago. We have to wait 11 months for our next shot.

Luckily, people who run telescopes are smart enough to have foreseen things like this long ago. The Hubble has a special proposal you can write at any time, called a Director’s Discretionary proposal, which can turn the telescope to a new target at a moment’s notice (well, ok, at a week or two notice). Just the thing!

So this week has been emergency proposal week. In between teaching geology class, writing a paper, preparing for a scientific talk at JPL on Monday, and spending time with my family, I wrote an emergency Director’s Discretionary proposal. It is not the best proposal I’ve ever written, but I think it makes the case. We need to know the precise orbit of Blitzen now so we can figure out when shadows and transits and occultations occur. And when we figure all of this out we need to make the information public as quickly as possible so everyone with a big telescope has the opportunity to make measurements of these events. And without the Hubble Space Telescope we will know this all too late. Therefore please please (pretty please) let us use the telescope.

The proposal goes to the director today. The decision is made by next week. If accepted, the pictures would be taken in a few weeks, and we would know when the first events would be occurring within about a month. Got a big telescope with which you want to chase a moon shadow with me? Stay tuned.

A new window on astronomers

One of the goals of this column is to make it more clear what astronomers actually do all day (or night) long. As I have been discussing, one of the things that I do frequently is writing proposals to convince other astronomers to let me use their telescope. The once-a-year proposals for use of the Hubble Space Telescope were due on Friday at 5pm (I pressed the “send” button at 4:49pm). Here is the proposal that I submitted. While it is written for other astronomers, so often flies into astronomical shorthand, I think it is at least moderately readable by anyone generally interested in what is going on in the outer part of the solar system. Plus, there is no chance I could possibly attempt to write anything else this week. In that spirit, here is:

A compositional-dynamical survey of the Kuiper belt: a new window on the formation of the outer solar system.

The eight planets overwhelmingly dominate the solar system by mass, but their small numbers, coupled with their stochastic pasts, make it impossible to construct a unique formation history from the dynamical or compositional characteristics of them alone. In contrast, the huge numbers of small bodies scattered throughout and even beyond the planets, while insignificant by mass, provide an almost unlimited number of probes of the statistical conditions, history, and interactions in the solar system. Studies of these small bodies have been exploited for many years in the inner part of the solar system, where combined dynamical and compositional observations of asteroids have been used to trace chemical gradients, study early radioactivity, and detect and analyze collisional histories in the region of the terrestrial planets (Bottke et al. 2005 and references therein). While a similar study of the Kuiper belt would offer similar promise for understanding the formation of the region of the giant planets, the typical objects in the Kuiper belt are 10,000 times fainter than those in the asteroid belt, so this promise has been hampered by the difficulty of obtaining concrete observations of the surface compositions of these objects.

Instead, attempts to understand the formation and evolution of the Kuiper belt have largely been dynamical simulations where a hypothesized starting condition is evolved under the gravitational influence of the early giant planets and an attempt is made to reproduce the current observed populations(Levison and Morbidelli 2003, Tsiganis et al. 2005, Charnoz and Morbidelli 2007, Lykawka and Mukai 2008). With little compositional information known for the real Kuiper belt, the test particles in the simulation are free to have any formation location and history as long as they end at the correct point. Allowing compositional information to guide and constrain these studies would add an entire new dimension to our understanding of the formation and evolution of the outer solar system.

New visible-infrared capabilities of WFC3 allow such compositional information of a large number of Kuiper belt objects to be obtained for the first time. Here we propose to exploit these capabilities to perform the first ever large-scale dynamical-compositional study of Kuiper belt objects (KBOs) and their progeny to study the chemical, dynamical, and collisional history of the region of the giant planets.

Kuiper belt compositions: the current view.
Combining compositional and dynamical information on small bodies has proved a powerful technique in the inner solar system for understanding the formation of the terrestrial planetary region, but it has only been used to a very limited extent in the outer solar system. Color diversity.The earliest attempts to jointly consider outer solar system compositions and dynamics simultaneously were attempted using only the colors of KBOs.While colors are a poor proxy for composition, they have proved a fascinating early tracer of the dynamical homogeneity -- and lack thereof -- of the Kuiper belt. The earliest photometric observations (Jewitt and Luu 1998) suggested that KBOs came in a wide variety of colors and that there was no relationship between the color and any orbital or physical parameter of the object. To date, this great heterogeneity remains unexplained, though it clearly points to a wide diversity of formation or evolutionary histories throughout the Kuiper belt.

The cold classical KBOs.
Subsequent observations of colors of larger numbers of KBOs eventually showed that one dynamical subset of the Kuiper belt, the ``cold classical KBOs'' on dynamically cold low inclination and eccentricity orbits, consists exclusively of objects that are red (Tegler and Romanishin 2000, Trujillo and Brown 2002). While the color red is impossible to interpret compositionally without more spectral information, the existence of this red grouping has been used to argue that the cold classicals are a unique population whose dynamical coherence has been maintained through the dramatic evolution of the outer solar system (Morbidelli and Brown 2004). The need to retain this group of objects is one of the key constraints on -- and sometimes the death of -- models of the evolution of the outer solar system and is the earliest example of the power of combining (even limited) compositional information with small body dynamics.

While color groupings have proved interesting for helping to understanding the evolution and rearrangement of the outer solar system, the actual cause for the different colors remains unknown.Infrared spectroscopy would allow a direct probe of the surface ices common in the outer solar system, but for many years few infrared spectra were available, as few KBOs were bright enough for even the lowest resolution spectroscopy with the largest telescopes. This difficulty was partially alleviated by our wide field search for the largest KBOs (Brown 2008), which finally provided a moderate number of bright observable objects, and by long term programs at VLT and Keck that slowly obtained spectra of the very brightest of these (i.e. Barucci et al. 2006, Barkume et al. 2008). The most systematic survey to date is our Keck survey (Barkume et al. 2008), which obtained 1.5 to 2.5 micron spectra of 45 objects in the outer solar system. Three results from this small sample provide examples and details of what could be expected from a much larger survey.

Fragments from a giant primordial collision.
One small set of KBOs stood out in the Keck survey for their unique spectra (Fig 1a). This collection of objects has surfaces which look like laboratory spectra of pure uncontaminated water ice. Moreover, all of these pure water ice objects have nearly identical orbits(Fig. 2a), and the largest of them, the nearly Pluto-sized 2003 EL61, had previously been speculated to have suffered a giant impact at some point in its past which gave it its rapid spin and system of at least two moons (Brown et al. 2006). The compositional and dynamical association of the water ice objects with 2003 EL61 itself made it clear that the small set of pure water ice objects were fragments of the giant impact that had shaped 2003 EL61 (Brown et al. 2007). This impact is the largest anywhere in the solar system for which we have multiple extant fragments identified, providing a unique laboratory into the types of massive collisions which shaped the solar system.

It is expected that the 2003 EL61 impact occurred during the time of solar system clearing when the Kuiper belt was significantly more dense than its current state. A model by Levison et al. (2008) suggests that the impact actually occurred between two objects which were themselves in the processes of being scattered out of the solar system. As would be expected from a collision of objects that were on unstable orbits, some of the 2003 EL61 family is itself in an unstable region of space. In Ragozzine and Brown (2007), we exploited these instabilities to develop a dynamical chronometer to use the current spread in orbital elements of 2003 EL61 fragments to determine the time of the 2003 EL61 impact. To date, with the small number of family members known, we can only place a lower limit of 1 Gyr on the age. But with more objects discovered we will be able to more precisely date this impact, and thus date the time of solar system clearing.While almost all models to date assume that major clearing occurred 4.5 Gyr ago, the new and to date quite successful Nice model (Tsiganis et al. 2005 and papers following) posits that solar system clearing was delayed by ~1 Gyr and did not largely occur until the time of the Late Heavy Bombardment. The study of the dynamics of this compositionally unique set of objects could answer one of the most important questions about the timing of major events in the outer solar system.

The methane giants.
Schaller and Brown (2007) suggested that a small number of the largest and coldest objects should have enough surface gravity to maintain their volatiles against loss to space over the age of the solar system. In their model, the final loss to space is controlled by the slow leakage of Jeans escape from a vapor-pressure controlled atmosphere. The loss is an intimate function of the object size and of the precise orbit. The results of the model predictions to date have been nearly perfect: almost everything that the model suggests should have volatiles on the surface (predominantly methane; Fig 1a) does, and nothing that the model suggests shouldn't have volatiles has been found to have volatiles. This success opens the possibility of being able to find outliers with unusual dynamical or compositional histories by finding objects whose predictions don't fit within the framework of the model. Indeed, the one object which doesn't fit the model prediction is 2003 EL61, the giant parent of the collisional family. We presume that the impact took away most of the volatiles on the outermost fragments, but, more importantly, even if we had know nothing else about 2003 EL61, its failure to have a predictable surface composition would have quickly drawn attention to it.

Overall spectral diversity.
Once the 2003 EL61 family is removed from the spectral sample, no apparent compositional-dynamical correlation or pattern is seen in the remaining 40 objects (Fig 2a). While the compositions of asteroids are strongly stratified as a function of heliocentric distance, the KBOs have no such stratification. Just as objects with different optical colors are jumbled throughout the Kuiper belt, so are objects with different infrared spectra. Unlike the asteroid belt, however, where compositional differences are glaring and distinct, in the Kuiper belt, the spectra of almost every KBO fits along a smooth continuum with the only differences being the amount of absorption due to water ice and the optical color (Fig 1b). While initially unexpected, the lack of other significant surface ices is now understood as a natural consequence of thermal escape of the more volatile ices (Schaller and Brown 2007).

Oddly, however, little correlation appears between the optical colors and the amount of water ice absorption (Fig 1b), conflicting with the commonly held conceptual view that KBO surfaces are a simple mix between red colors due to irradiated organics and blue colors due to fresh water ice exposed by collision (Jewitt and Luu 1998) or that KBOs can be compositionally classified by optical colors alone (Barruci et al. 2006).

While the cause of this continuous diversity is unknown, the broad possibilities are limited: the surfaces can reflect either primordial differences in the objects, subsequent evolution of the objects, or both. Primordial differences would likely reflect formation location, while evolution could reflect both thermal and collisional history.

Whatever the cause of the surface composition variability, understanding the reason would allow significant new insights into the evolution of the outer solar system. If the variations are primarily primordial, we could use KBO composition to reconstruct the initial locations of the objects that are now jumbled in the Kuiper belt, while if the variations are evolutionary we will be able to use compositions to reconstruct collisional or thermal histories of different regions of the Kuiper belt. In either case, with the current small number of objects known it is impossible to determine the cause of the variability, but the promise for this potential tool is strong.

The proposal continues on for another few pages, describing precisely how we want to use the Hubble Space Telescope to answer some of these questions that we had set out here.

Procrastination season

On occasion, my day job is going to interfere with finding the time to write these columns. For an astronomer, there are things like Jupiter season and the seasons of the moon, but there is also proposal season. And proposal season starts now.
For almost every telescope that I ever use I have to write a proposal convincing another group of astronomers that the project that I have in mind is worthy. Depending on the telescope involved and precisely when you want to use that telescope, the competition to be one of the people selected ranges from moderate to extreme. The proposal that is current occupying my time is one to use the Hubble Space Telescope. Even after 16 years in space, the Hubble is still one of the most sought after telescopes around. One of the reasons it continues to be so good is that every few years the Space Shuttle goes to the Hubble, fixes anything that may have broken, and installs newer more modern cameras. The last of these Shuttle refurbishments is slated to take place this summer, and afterward the Hubble will be equipped with the last ultimate cameras to scan the cosmos.
I am salivating to use these new cameras, and so are most of the other astronomers around. Who gets to use them and who doesn't will all be decided on the basis of proposals being written right now. Only about one in five will have a proposal accepted. I want to be one of them.
How to do it? How do you write a proposal that will be accepted? It's probably not unlike many other businesses. You need two key things: a great idea and a great sales pitch. Scientists often forget about the sales pitch part. After all, a strong scientific idea should be able to stand on its own, right? No chance. I have seen proposals with solid scientific ideas presented poorly, and they rarely even get looked at twice. Occasionally I've seen it the other way around: great sales pitch for a mediocre idea. To their credit, I think that scientists rarely fall for that, either. You really need both.
For the proposal I am currently working on I think I have a great idea to work with. I hope to do a large scale survey to understand the different types of objects in the region of space beyond Neptune. The proposal nicely builds on years of preliminary work we've done with telescopes here on earth, and it uses the Hubble study many more of these objects which are too faint to see from the earth.
It's a good scientific project. There are things that we know we will find, but there is also much room for unanticipated discovery.
But it's going to need a good sales pitch. Just like in every other profession, there are specialities that are trendy and those that are not. In astronomy, distant galaxies and supernovae and the earliest phases of the universe are trendy. Our solar system -- even the distant edge of our solar system -- is decidedly not. It's too small; it's too close; it's too specific. Why worry about the details of what happened in one insignificant corner of one insignificant galaxy when instead you could be studying the formation of the universe itself? I think there are good answers to this question. I think that without studying the details we will never know if our more general ideas are correct. And I think that the significance of our corner of the galaxy is vastly increased by the fact that is our corner.
But will I be able to sell it? I cannot predict, but decision will be announced on June 15th. Stay tuned. In the meantime, do not be surprised if proposal season takes its toll on these pages. But don't give up all hope. As can be seen even right now, writing these pages fullfills one important need without which no proposal could ever be completed: procrastination.

Pages

Godspeed

Nervous gyrations

I'm trying to follow a moon shadow

A new window on astronomers

Procrastination season