JAXA: Akatsuki: Japan's Venus Probe

[bystander]

Akatsuki captures goodbye shots of Earth
Planetary Society - 22 May 2010

Three of Akatsuki's six science instruments have now checked in as operating normally, producing lovely photos of the receding homeworld. They were taken at around 20:50 on May 21 (I think that is Japan time, so it would be 11:50 UT if that were true). At the time, Akatsuki was about 250,000 kilometers from Earth, which subtended about 3 degres of its field of view.

More importantly, Akatsuki is receding from Earth's night side, so the view is of a thinly lit crescent -- very pretty.

Earth as seen from Akatsuki's IR1 camera (JAXA / ISAS)

As Akatsuki sped away from Earth, it captured "First Light" images with its optical instruments pointed at its home planet in an extreme crescent phase. This view is from the IR1 camera, which captures images at a near-infrared wavelength of 0.9 microns, and a field of view 12 degrees square Once it gets to Venus, this camera will be used to look at cloud structure.

Earth as seen from Akatsuki's UV camera (JAXA / ISAS)

This view is from the UV camera, which captures images at a near-ultraviolet wavelength of 365 nanometers, and a field of view 12 degrees square. Once it gets to Venus, this camera will be used to observe the structure of the uppermost clouds.

The third instrument is a longwave IR one. It had the identical view of Earth, lit as a crescent by the Sun, but this wavelength is dominated by thermal emission from Earth's surface and clouds, so we can see the whole globe.

Earth as seen from Akatsuki's LIR camera (JAXA / ISAS)

As Akatsuki sped away from Earth, it captured "First Light" images with its optical instruments pointed at its home planet in an extreme crescent phase. This view is from the LIR or Longwave IR camera, which captures images at a wavelength of 10 microns. At this wavelength, Earth's surface as well as the cooler parts of Venus' atmosphere emit thermal radiation; even though most of Earth was in nighttime darkness at the time the photo was captured, it is glowing away with emitted heat. The cold (dark) spot at the bottom of the globe is Antarctica; Australia lies nearly at the center of the view.

[bystander]

Japanese Spacecraft Approaches Venus
NASA Science News | 16 Aug 2010

[url=http://apod.nasa.gov/apod/ap080226.html]APOD: Mysterious Acid Haze on Venus (2008 Feb 26)[/url] [i](Credit: ESA/MPS)[/i]

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Akatsuki: Venus Climate Orbiter (Credit: JAXA/Akihiro Ikeshita)

For the next few months, Venus will be softly resplendent in the evening sky, a treat for stargazers – but looks can be deceiving.

Consider this: The Venusian surface is hot enough to melt lead. The planet's 96% carbon dioxide atmosphere is thick and steamy with a corrosive mist of sulfuric acid floating through it. The terrain is forbidding, strewn with craters and volcanic calderas – and bone dry.

Takeshi Imamura can't wait to get there.

Imamura is the project scientist for Akatsuki, a Japanese mission also called the Venus Climate Orbiter. The spacecraft is approaching Venus and will enter orbit on December 7, 2010. Imamura believes a close-up look at Venus could teach us a lot about our own planet.
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Although a parade of U.S. and Soviet spacecraft has visited Venus since 1961, no one yet knows how it became Earth's "evil twin." Did it suffer from a case of global warming run amok – or something else? When Akatsuki reaches Venus in December, it will begin to solve some of the mysteries hidden in the thick Venusian atmosphere.
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Particularly puzzling is Venus's "super-rotation." Fierce, blistering winds propel an atmosphere filled with storms and sulfuric acid clouds in a churning maelstrom around Venus at over 220 miles per hour, 60 times faster than the planet itself rotates.
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Within this swirling cauldron are other Venusian riddles to be solved: What is the origin of the 12-mile thick layer of sulfuric acid clouds that shrouds the planet? And how does Venus' lightning crackle through this strange brew?

Akatsuki, bristling with cameras, will circle the exotic planet's equator in an elliptical orbit for at least 2 years, monitoring the atmosphere at different altitudes using various wavelengths (IR, UV, and visible). With this data and data from the spacecraft's radio dish, scientists will reconstruct a 3D model of the atmosphere's structure and dynamics.
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The instruments will also scrutinize the planet's surface for volcanic activity that could be contributing to the sulfur contents of the atmosphere. ... In addition, Akatsuki's Lightning and Airglow Camera will hunt for lightning in order to settle a longstanding debate. ...

Imamura can scarcely contain his curiosity. "As a young boy I loved to watch clouds, stars, oceans, rocks, and creatures. I wanted to understand why they look and behave as they do. Now I am curious in the same way about Venus. Nature is so full of mysteries!"

Beginning in December, some of Venus's mysteries will be revealed. Stay tuned.

[bystander]

Akatsuki has failed to enter Venus orbit
Planetary Society | 07 Dec 2010

There is a press briefing happening right now in Japan, and it's terrible news: Akatsuki failed to enter Venus orbit, nor will it be able to enter Venus orbit -- at least, not for at least 7 years, which is the next time it'll be back near Venus. It's a repeat of the sad fate of the Nozomi mission to Mars. What horrible luck.

Twitter is very active with reporting on the press briefing right now. My plan is to wait until tomorrow morning, then see what has developed over my night. During the Japanese day, I hope, news will become clearer about what exactly went wrong. In the meantime, I suggest following natsu_shigure on Twitter, who is translating Japanese blogger Koumei Shibata's Tweet's from the press briefing.

Space exploration is hard. It's a terrible shame. Hopefully they will manage to salvage some sort of science from this ambitious mission.

[neufer]

Akatsuki has failed to enter Venus orbit
Planetary Society | 07 Dec 2010

There is a press briefing happening right now in Japan, and it's terrible news: Akatsuki failed to enter Venus orbit, nor will it be able to enter Venus orbit -- at least, not for at least 7 years, which is the next time it'll be back near Venus. It's a repeat of the sad fate of the Nozomi mission to Mars.

<<Nozomi (のぞみ) (Japanese for "Wish" or "Hope," and known before launch as Planet-B) was planned as a Mars-orbiting aeronomy probe, but was unable to achieve Mars orbit due to electrical failures. It was constructed by the Institute of Space and Astronautical Science, University of Tokyo and launched on July 3, 1998 at 18:12:00 UTC with an on-orbit dry mass of 258 kg. The spacecraft flew by Mars on December 14, 2003 and went into a roughly 2-year heliocentric orbit. Though its mission has been abandoned the spacecraft is still active.>>

[neufer]

JAXA Considering Second Try at Akatsuki-Venus Rendezvous One Year Earlier than Planned
by Nancy Atkinson on January 5, 2011

Way High Altitude Mapping Orbit

Akatsuki probe

<<The Japan Aerospace Exploration Agency (JAXA) is now considering making a second attempt to insert the Akatsuki probe into Venus’ orbit one year earlier than originally planned, in five years instead of six. After a malfunctioning valve in the spacecraft’s fuel pressure system caused the engine to function abnormally, Akatsuki failed to enter Venus’ orbit on Dec. 7, 2010 as planned. JAXA had said the spacecraft’s orbit around the Sun would put it in position for another orbit insertion attempt in about six years. But because the spacecraft’s speed has slowed more than expected, the agency now says it may be possible to slowly decelerate Akatsuki even more and let Venus “catch up with it,” according to a report in the Mainichi Daily News. A quicker return to Venus is also advantageous in terms of the lifespan of the probe and its equipment.

“At the speed the probe was moving under our first retry plan, it would probably have been impossible to make the orbital insertion,” said a JAXA official, quoted in the Japanese online news site. “We hope to explore every possibility, and make an exploration of Venus a reality.”

After the original mission failure, JAXA had calculated that Akatsuki would make 11 trips around the Sun for every 10 Venus made, putting the next closest encounter between the spacecraft and planet sometime in December 2016 or January 2017. But subsequent examination of data showed Ataksuki’s engine power had dropped by almost 60 percent, possibly caused by a malfunction in the fuel supply system or damage to the engine nozzle. If that is the case, the prospects for restoring full function are very low. Additionally, if the engine nozzle has been weakened, it will be difficult to decelerate the Akatsuki enough for orbital insertion when it again closes with Venus. But after consultations with engineers, JAXA is now considering trying to decelerate the craft a little bit at a time, allowing it to make eight orbits around the sun before Venus catches up with it in five years.>>

[bystander]

Japan test fires Venus probe engine
PhysOrg | AFP | 2011 Sept 08

[img3="This illustration created by Akihiko Ikeshita and received from Japan Aerospace Exploration Agency (JAXA) in December 2010, shows an artists impression of The Planet-C Venus Climate Orbiter, nicknamed "Akatsuki" or "Dawn", orbiting Venus."]http://cdn.physorg.com/newman/gfx/news/ ... aysith.jpg[/img3]

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Japan said it had successfully test-fired the engine of its "Akatsuki" space probe in preparation for a renewed attempt to get it into orbit around Venus in 2015.

Following December's failed attempt to send the probe to the second planet from the sun, a remote test ignition conducted Wednesday lasted for 2 seconds as planned, the Japan Aerospace Exploration Agency (JAXA) said.

"The failure in December was highly likely due to engine damage," said JAXA spokesman Eijiro Namura.

"We have made the first step forward by igniting the engine for the first time since then," to assess its condition, he said.

The "Akatsuki", meaning "Dawn" is fitted with two paddle-shaped solar panels and blasted off in May last year on a 25.2 billion yen ($300 million) mission to observe the toxic atmosphere and super-hot volcanic surface of Venus.

But in a setback for Japan's space programme, the box-shaped probe failed to enter the planet's gravitational pull and shot past it in December. It is still in space.

Another, longer engine test ignition of the probe -- officially known as the Planet-C Venus Climate Orbiter -- is planned for September 14.

Based on the test results, JAXA plans to fire up the engine in early November in order to adjust the craft's positioning ahead of the next available window for a Venus orbit attempt in 2015 or later, according to the agency.

Scientists believe that investigating the climate of Venus would deepen their understanding of the formation of the Earth's environment and its future.

(c) 2011 AFP

[bystander]

Akatsuki to try for Venus orbit in June 2016
Planetary Society | Emily Lakdawalla | 2012 Jan 31

Date has been corrected to June 2016 (original article had December 2016). And it's no longer clear that there's been a formal decision to enter orbit on that date rather than in 2015 or later. See the notes below. -- ESL

[i][b]Akatsuki: 'I'll be back!'[/b] (Credit: JAXA)[/i]

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Japan's Venus climate orbiter Akatsuki failed to enter orbit in December 2010 when a clogged valve caused catastrophic damage to its main engine. Since then, JAXA's engineers and navigators have determined that although the main engine is a total loss, there is the possibility of achieving Venus orbit on a future encounter, using only the attitude control rockets. They reduced their mass as much as possible by venting the oxidizer that would have been used in the main engine, and have begun a series of deep-space maneuvers to slowly nudge the orbit to one that could enable Akatsuki to achieve Venus orbit in the future.

The closest flyby of Venus will take place in November 2015, and as of last year, JAXA planned to use the attitude control rockets to enter orbit then. However, a new report indicates that the team prefers the next closest opportunity in December June 2016. They prefer it because the geometry of that encounter allows Akatsuki to attain an elliptical orbit from which they can recover some science, doing cloud observations, while the orbit achievable from the 2015 encounter would be much less favorable for science.

This assumes that the spacecraft remains healthy. If Akatsuki's systems have deteriorated markedly before the 2015 encounter, then JAXA will consider trying for the earlier opportunity.

This news appeared in the Yomiuri Shimbun newspaper, and unmannedspaceflight.com user "pandaneko" translated its main points here.

EDIT 22:30 UT: Here are some notes by @ots_min and some other notes by @iwamototuka (both in Japanese) on today's press briefing, ... Twitter user @hee913758 translates the high points of the first set of notes thusly:

• JAXA to make Akatsuki reenter Venus' orbit in Nov. 2015, or June 2016. (Or later). A few possibilities. It depends on the probe's condition. JAXA will have finally decided when to make it reenter by around 2014. The more times it performs [Venus] swing-by, the better orbit it can enter. (However the more its condition deteriorates.)
  
  Project Manager Nakamura: Even if the valve completely clogged, current pressure would able to push the propellant well. PM.Nakamura: I'm'afraid it's CCD that deteriorates the fastest in all cameras. It's gotta stand the radiation WITH GUTS!

[bystander]

Akatsuki: Re-injection to Venus Orbit and Observation Plan
Japan Aerospace Exploration Agency (JAXA) | 2015 Feb 06

The Japan Aerospace Exploration Agency has decided the schedule for the Venus Climate Orbiter “AKATSUKI” to be injected into the Venus orbit in the winter of 2015, as well as its observation plan.

After failing to be inserted into the Venus orbit in December 2010, JAXA has been carefully studying another attempt opportunity for the injection when the orbiter meets Venus in the winter of 2015. (Planned date: Dec. 7 (Mon.), 2015 (Japan Standard Time))

After being injected into the orbit, the AKATSUKI will observe the atmosphere of Venus, which is often referred to as a twin sister of the Earth, through remote sensing. Its observations are expected to develop “Planetary Meteorology” further by elucidating the atmospheric circulation mechanism and studying the comparison with the Earth. ...

JAXA | Venus Climate Orbiter "AKATSUKI"

[bystander]

AKATSUKI attitude control engine thrust operation performed as scheduled
Japan Aerospace Exploration Agency | Akatsuki | 2015 Dec 07

JAXA performed the attitude control engine thrust operation of the Venus Climate Orbiter “AKATSUKI” for its Venus orbit insertion from 8:51 a.m. on December 7 (Japan Standard Time).

As a result of analyzing data transmitted from the orbiter, we confirmed that the thrust emission of the attitude control engine was conducted for about 20 minutes as scheduled!

The orbiter is now in good health. We are currently measuring and calculating its orbit after the operation. It will take a few days to estimate the orbit, thus we will announce the operation result once it is determined.

[bystander]

Venus Climate Orbiter "Akatsuki" Inserted into Venus' Orbit
Japan Aerospace Exploration Agency | Akatsuki | 2015 Dec 09

[img3="Venus image taken by AKATSUKI immediately after its attitude control ejection, by Ultraviolet Imager (UVI), at around 2:19 p.m. on Dec. 7 (JST) at the Venus altitude of about 72,000 km"]http://global.jaxa.jp/press/2015/12/ima ... ki_2_3.jpg[/img3][hr][/hr]

The Japan Aerospace Exploration Agency (JAXA) successfully inserted the Venus Climate Orbiter “AKATSUKI” into the orbit circling around Venus.

As a result of measuring and calculating the AKATSUKI’s orbit after its thrust ejection, the orbiter is now flying on the elliptical orbit at the apoapsis altitude of about 440,000 km and periapsis altitude of about 400 km from Venus. The orbit period is 13 days and 14 hours. We also found that the orbiter is flying in the same direction as that of Venus’s rotation.

The AKATSUKI is in good health.

We will deploy the three scientific mission instruments namely the 2μm camera (IR2), the Lightning and Airglow Camera (LAC) and the Ultra-Stable oscillator (USO) and check their functions. JAXA will then perform initial observations with the above three instruments along with the three other instruments whose function has already been confirmed, the Ultraviolet Imager (UVI), the Longwave IR camera (LIR), and the 1μm camera (IR1) for about three months. At the same time, JAXA will also gradually adjust the orbit for shifting its elliptical orbit to the period of about nine days. The regular operation is scheduled to start in April, 2016.