IKAROS now appears to be fully deployed and generating power from its photovoltaic cells. The IKAROS blog even has a photo of the cake with which the sail team celebrated the success, but you’ll also want to go to this IKAROS page for a look at further imagery, one of which is the photo shown below. The page has four similar photographs from different cameras aboard the spacecraft, and if I’m reading this right, more photos will be posted here as they become available. JAXA has also made available this news release about the deployment.
Lionel Ward, our Japanese translator extraordinaire, will be sending translations of the IKAROS blog postings and recent tweets from JAXA later today, and I’ll post these as a way of archiving the information here. This afternoon (1800 or so UTC) I’ll have today’s regular Centauri Dreams post up, but I wanted to share this image and give you the pointer for more as soon as possible. What an achievement this mission has turned out to be even this early on, and we now have a fascinating period ahead when we learn about the sail’s responsiveness, its maneuverability and its overall functionality. Once again, congratulations to project leader Osamu Mori and the entire IKAROS team!
One of the problems with determining how planets form is the nature of the dusty gas-rich disks that surround their stars. We’re learning as we study these things that the disks around young stars disperse quickly in astronomical terms, within several million years. Thus finding a massive planet around a young star like Beta Pictoris is noteworthy. It demonstrates that such planets can form in short-order. What’s doubly fascinating about the new find is that this planet was discovered by direct imaging techniques, and that it is as close to its star as Saturn is to ours.
Have a look at the imagery below, made using the European Southern Observatory’s Very Large Telescope and an adaptive optics instrument that removes atmospheric blurring and other effects. It’s a composite showing the faint source in the 2003 image and contrasting it with the motion of the object as seen in the autumn of 2009. The object can be seen to have moved to the other side of the disk. As we only have direct images for a small number of exoplanets, Beta Pictoris b enters into select company, while the small size of its orbit (8-15 astronomical units) will offer the chance to record a full orbit within 15 to 20 years.
Image: The above composite shows the reflected light on the dust disc in the outer part, as observed in 1996 with the ADONIS instrument on ESO’s 3.6-metre telescope. In the central part, the observations of the planet obtained in 2003 and autumn 2009 with NACO are shown. The possible orbit of the planet is also indicated, albeit with the inclination angle exaggerated. Credit: ESO/A.-M. Lagrange.
Beta Pictoris is about twelve million years old, 75 percent more massive than our Sun. Located some 60 light years away in the direction of the constellation Pictor (the Painter), it has long been known to be surrounded by a circumstellar dust disk extending several hundred AU from the star. 25 years of observations at wavelengths from optical to thermal infrared have shown the presence of multiple disk structures and tantalizing asymmetries — in particular, a warp in the disk plane — that suggested the presence of massive planets. The new work confirms the idea, and also offers interesting evidence for planet formation models. From the paper (internal references removed for brevity):
A comparison of the luminosity of ? Pictoris [8.7 LSun] to that of the Sun suggests that the orbit of ? Pictoris b lies at or slightly beyond the disk radius outside which water is stable as ice (snow-line). The snowline is thought to separate disk regions where rocky or gaseous/icy planets form… Indeed, beyond the snowline, the disk surface density is expected to be higher (factor of 3) than that inside the line; this allows giant planet cores (10 MEarth) to form before the dispersion of the gaseous nebulae. Core accretion models suggest indeed that this latter step – the onset of rapid gas accretion before the loss of circumstellar gas – is the critical step in forming giant planets.
The core accretion model holds that dust particles gradually accumulate to become the rocky bodies we call planetesimals. The planetesimals themselves eventually collide to create a massive core that then attracts an outer layer of gas. Usefully, Beta Pictoris b seems to confirm core accretion to a high level of detail. The paper goes on:
For a 2 MSun star, the snowline location varies between 2.5 and 4 AU for ages between 1 and 10 Myr, respectively. In the case of the 1.75 MSun ? Pictoris, core-accretion based models predict a rapid formation of giant protoplanet cores between ~ 6 and 18 AU. The observed orbital radius of ? Pictoris b is consistent with this range, demonstrating that the planet could have formed via core accretion on the same orbit where it is observed today. This possibility is in contrast to the case of the more distant planets Fomalhaut b, HR8799bc, AB Pic b, and 2MASS 1207b, which are too massive… to have formed at their present separations (40 AU or larger), via core accretion.
In addition to showing how quickly planets can form within circumstellar disks, this work is also valuable because it shows that planets deeply embedded in these disks can be teased out by close examination of the disk structure. The short orbital period of Beta Pictoris b should make it the object of intense study as we learn more about how such worlds distort their surrounding disks. The paper is Lagrange et al., “A Giant Planet Imaged in the Disk of the Young Star ? Pictoris,” Science, published online June 10, 2010 (abstract).
Update: As of 1611 UTC, the IKAROS blog is reporting “IKAROS state has been confirmed to be good.” More images and data are in the works, but we’re not likely to see anything until tomorrow.
It’s getting late in Japan (2306 JST as I write, or 1406 UTC), and although a JAXA tweet promised new photos for today, the IKAROS blog is still showing the same deployment image we looked at yesterday. More as it becomes available and, naturally, I’m also following the fortunes of Hayabusa, now on final approach to the Woomera Test Range in South Australia. Re-entry is targeted for June 13. Meanwhile, I’m holding on a story (not on IKAROS) that comes off embargo this afternoon and will be posting today’s main entry in a few hours.
Update: The IKAROS blog reports “The operation ended today as planned.” That must count as good news for the sail, now 7,480,787 kilometers from Earth, but we still need confirmation that the sail’s ‘secondary’ deployment is now complete. Maybe this is it: Japanese space journalist Mitsunari Kita, who is attending a press conference re the Hayabusa mission, has sent out a tweet (@kitamitsunari) congratulating the IKAROS team on full deployment of the sail (1805 UTC).
What extraordinary times these are for the Japan Aerospace Exploration Agency (JAXA). We are in the midst of an interplanetary solar sail mission even as the Hayabusa asteroid explorer prepares for re-entry over Australia, an event that should occur around 1400 UTC on June 13. The Hayabusa craft will release its 16-inch-wide entry capsule some three hours before landing. We’ve concentrated on IKAROS in these pages, but what a story Hayabusa has been, launched in 2003 to explore the asteroid Itokawa, which it did, but not without a series of technical problems affecting communications and producing a fuel leak that drained its chemical propellant. Engineers brought the crippled craft home using low-thrust ion engines in a masterful series of deep space fixes.
Hayabusa may have failed in its attempt to gather rocks and soil on Itokawa, but it’s hoped that at least some residual matter from the asteroid may be aboard the return capsule. We’ll soon know. In the meantime, the IKAROS sail team has been busy with the sail’s deployment, pausing it briefly because of unexpected spin, and resuming it yesterday. The IKAROS blog announced seven hours ago (0502 UTC) that the primary sail deployment — this refers to extension of the booms to full length — had been completed successfully and that secondary sail deployment will take place about now, which means early afternoon UTC as I write and in the late evening Japan Standard Time.
It’s in the secondary stage of deployment that the sail itself emerges, a critical time for the mission. IKAROS carries onboard cameras so we have several views like the one below showing what the blog calls ‘primary expansion driven by the relative rotation mechanism.’ The diagram above gives an idea of what we are looking at as the booms are extended.
The final image, released about five hours ago, shows the sail after primary extension of the booms and appears to show sail material in strong sunlight, along with associated tethers and harnesses. We should get more imagery soon as the process continues.
Lionel Ward, who has done such yeoman work translating the Japanese from the IKAROS blog and various tweets, offers up this translation that accompanied the photo from the IKAROS team:
These are photographs taken after yesterday’s completion of primary deployment yesterday. Due to intense sunlight, in the photograph there is the appearance that the two tethers connecting the sails to the probe’s body are piled on top of each other. However, since the side of the sail close to the probe’s body is in shadow, and the incident light there is weaker, we can confirm that the tether and membrane harness are photographed.
Which basically means, I think, that despite the appearance of a tangled tether, the sail was in good shape at this point in the deployment.
Update: The IKAROS team has not confirmed full deployment of the sail, but does indicate we’ll have an update tomorrow.
The IKAROS solar sail is partially deployed but the complete deployment was delayed while the mission’s engineers tried to figure out why the spacecraft’s spin rate has been increasing. JAXA’s updates are in Japanese, but the Planetary Society’s Emily Lakdawalla seems to be more skilled at untangling Google Translate than I am and has also used a translation from a user on the excellent unmannedspaceflight.com site to come up with IKAROS details. Thus we learn that the sail is currently deployed about five meters. A new update just in from JAXA points to an attempt at full sail deployment just a few hours from now. This video shows the process at work.
From what JAXA says, there is no danger to the spacecraft from the increased spin rate, but the pause in deployment arose simply because the team wanted to pin down an explanation for the behavior before proceeding. I suspect we’re going to run into many a mystery like this one as we get solar sails shaken out on actual missions. The push of solar photons may account for the spin, or we could be looking at the interesting phenomenon of outgassing of sail materials. You may remember that James and Gregory Benford have studied sail outgassing and pondered using such effects for directed propulsion in future sails.
The difference here is that the IKAROS team has evidently not expected this outgassing, if that is what is causing the spin changes, and has been understandably cautious with IKAROS before proceeding to final deployment. The last reported spin rate I’ve seen seems to be a stable 7.4 rotations per minute. This morning, a new post on the IKAROS blog refers to full expansion of the sail scheduled for June 8, listing the event at ‘evening-midnight’ JST, which would make it no later than late morning EST or mid-afternoon UTC today.
ADDENDUM: My mistake. The full expansion the IKAROS blog talks about seems to refer to full extension of the boom structure. JAXA calls this ‘primary development,’ as opposed to the ‘secondary development,’ which is release of the sail material itself. The latter now seems to be scheduled for June 9 — more tomorrow.
Translating IKAROS Tweets
At the same time, the IKAROS team has been sending out tweets in Japanese which Centauri Dreams reader Lionel Ward has been kind enough to translate. Lionel is an amazing linguist, much better than Google Translate. I won’t reproduce all of these, but some of the more recent ones are quite interesting, and you’ll note that some come via the AKATSUKI Venus orbiter team. The times listed are off by about twelve hours, as Lionel passed these along last night:
IKARUSKUN about 13 hours ago
I’m doing fine. I’m having my distance measured (ranging)
about 12 hours ago via web
AKATSUKI: From the Sagamihara control room: Akatsuki is continuating on a steady course towards Venus. At the same time, Akutsuki will from here on be preparing for observations and experiments. During the 3 weeks spanning last week to next week, the ??? (Positioning System?) team has the main role.
about 12 hours ago
AKATSUKI: There is a very slight force being felt from sunbreams, however it will gradually build up and lead to a negative effect upon Akatsuki’s posture (interference/noise). Hence a position which will incur minimal force from sunlight pressure is being searched for.
about 11 hours ago
IKARUSKUN @Akatsuki_JAXA Akatsuki, you are feeling the effects of sunbeams! I wonder if I am
about 11 hours ago
AKATSUKI @ikaroskun
Yes indeed! There is apparently influence upon me from the Sun’s rays. Perhaps you may also be starting to be influenced by the Sun too Ikaros-kun. Once you’ve completely opened your sails, you’ll ride along upon the sun rays! How wonderful…
about 10 hours ago
IKARUSKUN @Akatsuki_JAXA Yes, because my sails are extended into a cross shape, the sunbeams are hitting me and warming me up! The Sagamihara Centre is checking whether it’s caused by the sunbeams or not
about 10 hours ago
IKARUSKUN I’m about 6.7 million km from Earth. And I’m separated from my big brother Hayabusa too…
about 8 hours ago via web
IKARUSKUN Usuda Centre has gone out of view to the opposite side [of earth]. Today we spoke together lots.
about 8 hours ago
IKARUSKUN @Hayabusa_JAXA Yeah, I’m doing well, and trusting in what I’ve been told from Earth, and trying my hardest!
The first-person informality is fun, and Lionel tells me that the ‘kun’ in IKAROS-kun is an affectionate suffix that older people use when calling boys by their names. Let’s hope the sense of good humor persists as the IKAROS team works through the potentially tricky deployment. This is in many ways the most dangerous part of any sail mission, for you’re dealing with remarkably thin films on the one hand (the sail itself) and a structure of spars and struts needed to get the sail into position. What a relief it will be when this is done and we start getting data from an operational sail!
In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For many years this site coordinated its efforts with the Tau Zero Foundation. It now serves as an independent forum for deep space news and ideas. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image courtesy of Marco Lorenzi).
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