Archive for the ‘New Horizons’ category

So Is It A Planet?

August 24, 2009

And Why Not???

Pluto From New Horizons

Pluto From New Horizons

From CNN on-line:

It was three years ago Monday that the International Astronomical Union demoted Pluto from a planet to a dwarf planet, a decision that made jaws drop around the world.

An outcry followed, textbooks had to be rewritten, long-held beliefs were shattered, and many people felt our cosmic neighborhood just didn’t seem the same with eight — instead of nine –planets in the solar system.

Well, even though I was working on the New Horizons Mission to Pluto at the time, my jaw didn’t exactly drop. The debate had been going on for awhile. Besides. It’s just nomenclature. As it was, ever since Arthur C. Clarke pointed out that Europa was every bit as interesting as Jupiter, astronomically speaking, many of us had sort of realized early on that there was more to the Solar System than just planets, comets and asteroids.

Not that planets were downgraded, mind you. It was more like everything else was upgraded in importance. The icing on that particular cake was that astronomers began to realize that even the planets were more varied than originally supposed. There weren’t just two kinds; rocky like the Earth and gaseous-giants like Jupiter. It seems better now to recognize that Uranus and Neptune might be yet a third class – with interiors that are much different than the others, and with unique formation-histories to boot. The discovery of large ice-balls in the outer solar system, of which Pluto is  the earliest known (and probably best) example, is merely the last step in that march.

So, planet or no, Pluto is going to be a great place to visit.  Too long a commute to live there, however.

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New Horizons: No News Is Good Snooze

February 8, 2008


I haven’t written much on the unmanned New Horizons Mission to Pluto of late, mostly because there’s been little if anything to report. The spacecraft went behind the sun (from our point of view here on earth) at the end of December, and was out of contact for less than a week. That always drives the controllers a little nutz, but it is, of course, unavoidable for most deep space missions.

Thankfully for N.H., nothing happened. Moreover, not much has happened since, except routine maintenance. The weekly report is full of phrases like “…the spacecraft remained…”, “…the NH spacecraft returned to the nominal operations concept…”, “Spacecraft maintenance events…” and most importantly, “The spacecraft is healthy and operating nominally.”

As Newman would say, “Eeeexcelllllent”.

Last November N.H. thought it detected a “current overload”, which caused its nervous Autonomous Control System to make the spacecraft go into the fetal position and phone home with a little whimpered cry of “help”. Ground controllers were concerned enough to examine the event carefully. Very carefully. They came to understand in about a week that the over-current was an artifact of the configuration that the spacecraft was in, it was not serious at all in that it was not going to damage anything, and that Autonomy was overreacting. The next step was to create a new version of the Autonomy software that could handle the condition better. That version was tested and uploaded less than a month later.

Since then, N.H. has been monitored closely using the Deep Space Network of receiving antennas that listen to deep space missions (and chew up budgets). That same condition has reoccurred at least twice, but now Autonomy does not cause the spacecraft to have fits of panic. So the decision was made to let N.H. go into a passive mode on February 1, where nearly continuous monitoring won’t be necessasry. The DNS will check in every couple of weeks or so to make sure that N.H. is still sleeping peacefully.

In case you were wondering, New Horizons is long past Jupiter, and is most of the way to the orbit of Saturn (the planet itself is on the other side of the sun). It takes a signal sent from earth nearly an hour and a half to get to the spacecraft.

Out From Behind The Sun

January 22, 2008


I haven’t mentioned much about the New Horizons spacecraft of late, mostly because there has not been much to tell. Weekly reports indicate that it nothing of note happened when it spent several days out of communications behind the Sun. Although the “meaningless” overcurrent condition that caused a little consternation in December did indeed repeat itself, the software uploaded to correctly detect and handle the signal has worked fine.

New Horizons should be quite (update and apology – I meant to type “quiet”, but fat-fingered it. The spell checker is, of course useless in these situations! -jb) about now, cruising peacefully through space in a sleep mode. It isn’t exactly. It’s a little awake for the sake of monitoring, but mostly comatose. (For Alan Stern’s take on the current mission profile, see here.)

But science goes on. The data taken by New Horizons last spring as it sped by Jupiter has just been released to the public (Hey! You paid for it. It’s yours!), along with some basic tools to deal with it. So along with the pros, you too can do real science, if that is your inclination.

Amazing world, isn’t it? Between spacecraft releasing data in near real time and archives like the SDSS, who needs a telescope? It’s all there for you online.

Glitch

December 2, 2007

I noted late last month that the New Horizons spacecraft (on its merry way to Pluto) has had a bit of difficulty. The problem is that the solid state recorder (SSR) gave an indication that it was drawing too much current. The control system then properly decided to shut it down, temporarily, and use the spare.

That’s fine, and indeed, that’s the proper response. The kicker was that NH (and in particular, the Autonomous Control System) went a little overboard and put the space craft in safe mode. Well, that’s not too serious – it’s just a bit of an overreaction that causes some re-scheduling to be necessary. It takes a bit of time to come out of safe mode, because it’s supposed to be a slow, painstaking procedure so that everyone concerned is convinced that it’s okay to proceed to the next step. The team immediately began working on an update to the Autonomous Control System to allow it to diagnose the condition and distinguish it from current overloads in other places (like instruments and on-board processors) where it becomes much more vital to shut down everything.

But the over-current happened again last week.

I don’t know how much of an overcurrent was detected – I’ve seen no indication that they were seriously over the limits, or if the events could be considered transitory. I suspect the former is closer to the truth.

It could also be just a one-time glitch that unfortunately just happened twice, and those kinds of things do happen in space. But as of now, the real, proximate cause is still under investigation.

Other than that concern the space craft is very healthy.

You can subscribe to New Horizons e-news to keep abreast of the latest developments. With a bit of luck, the news will be boring until 2015 when we get to Pluto.

New Horizons News

November 20, 2007

Every six weeks or so, New Horizons Principal Investigator (and current head of NASA’s Science Mission Directorate), Alan Stern, writes a column posted on John’s Hopkins New Horizons Web Site, called The PI’s Perspective. I’ve been waiting for this one, because since the last update in early October, the mission deviated a bit from it’s original time line. Stern explains:

We did have a couple of unexpected events during ACO-1. (ed. ACO is Annual Check Out.) One came in early October, when the spacecraft partially lost track of its timeline owing to a very subtle kind of error generated by a command script we’d sent it. The operations team caught this and recovered from it very quickly. It was really a blessing that this subtle behavioral flaw manifested itself now, rather than at Pluto, so we can protect against it. It’s these kinds of idiosyncrasies that our testing and flight operations hope to expose. So, despite the fact it cost us some lost sleep and some cruise science observations, we’re very glad to have learned this lesson.

Yeah – I saw this news just after it happened, in the regular weekly report. It’s a rather expected kind of unexpected problem that comes up regularly in these kinds of environments. He’s being polite, but you can be sure that someone felt like (s)he made a dumb mistake somewhere.

The second unexpected event came just last week, on November 12, when a cosmic ray or some other kind of charged particle caused our main computer to reboot. This is the fourth such computer reboot we have had in flight caused by space radiation bursts. Preflight predictions were for these events to be far more rare than this, and our engineering team is looking into why this is occurring more often than predicted. Fortunately, on the four occasions this occurred, the onboard spacecraft autonomy software performed as planned and recovered New Horizons safely.

Hum… This is happening rather frequently…The first time was even before I left the mission. The middle two times were attributed to Jupiter’s intense radiation belt, but apparently, they’re not satisfied with this explanation any more. Could it be a harbinger of a potential problem? Hope not.

The third and final such event took place on November 16, when the spacecraft’s main computer executed a power on reset (POR) because of a glitch on its power line. Since this was so unexpected, we are analyzing what happened and have decided not to enter hibernation until late December while we analyze the root cause of this anomaly and put in place some software protection against future events. For the next couple of weeks, we’ll monitor the spacecraft three to four times a week using NASA’s Deep Space Network to collect more data.

Eeeechh. This is not good. Perhaps not real bad (yet), but unexplained power glitches really aren’t a good thing when your about six hundred million miles away from home (as the crow flies). I saw the news of this too, last week, in the weekly report and I really forgot to mention it here. I also noted that the spacecraft was not put into hibernation as originally planned.

The mission will be using quite a bit of “Deep Space Network” time in the next few weeks. That’s expensive. Is this the reason that Stern says “Budget constraints will force us to slim down the team in mid-2009, so we need to finish the Pluto planning before many of the Jupiter encounter team members move on to other projects.”? It’s probably a factor. New Horizons was supposed to spend much of it’s flight time to Pluto “sleeping”, relying on its Autonomous Control System and nearly no support from the ground to save years and years worth of FTEs on the budget. And in the spirit of full disclosure, I spent my time testing the autonomy system, as one of those FTEs.

Finally Stern mentions that NH is planning to spend forty weeks in hibernation next year. The spacecraft is behind the Sun (from our perspective on Earth) starting in the middle of December and will be out of touch for just about two weeks. So the plan is to put it to sleep about the first of the year, and keep it there at least until May.

[voice type=demonic, class=”Price, Vincent”]
And then my autonomy system will have complete control over the spacecraft, and THE MISSION IS MINE. MINE! ALL MINE, I SAY!
[laugh type=evil, class=”mad scientist”]
AhhhHAHAHAHAAAA!
[/laugh][/voice]

Hot, Steaming New Horizons News

October 11, 2007

In Orlando, Fla., the Planetary Sciences Division of the AAS finally gets around to discussing New Horizons.
Highlights:

    Jovian weather
    Clearest images ever of Jupiters incredibly thin ring system
    Dogs not barking – Jupiters small moons are missing!
    Volcanic eruptions!
    Best science of Jupiter’s magnetotail. Ever.

From the link above:

The New Horizons team presents its latest and most detailed analyses of that data today at the American Astronomical Society’s Division for Planetary Sciences meeting in Orlando, Fla., and in a special section of the Oct. 12 issue of the journal Science. The section includes nine technical papers written by New Horizons team members and collaborators.

And, there’s more!

New Horizons Comes Out of Its Coma

July 14, 2007

New Horizons was brought out of its “controlled” coma on Thursday (7/12/07), for no other reason than to see that it could be done. Ok, I lied. There were (and are) plenty of reasons to keep it alive and awake for the entire trip. But putting the spacecraft to sleep is so much more economical, and in some cases, safe for the instruments, that it was the seen as the better plan by the powers-that-be at APL and NASA from the beginning. That is, it’s better so long as the spacecraft wakes up properly.

It did.

Signals from New Horizons that it had come out of its electronic slumber – during which the guidance and control system and most science instruments were powered off – came through NASA’s Deep Space Network and reached mission operators at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Md., just before 2 a.m. EDT. The spacecraft was 550 million miles from Earth, cruising toward the outer solar system at nearly 46,000 miles (74,000 kilometers) per hour.

Per mile, this has to be NASAs least expensive mission yet. From now until Pluto (July 2015), New Horizons will spend most of its time in a coma. It’s good to know that, so far, it’s going exactly as planned (knock on lots of wood!).