Akatsuki Venus Orbital Insertion

[Streetwind]

3 hours ago, Mitchz95 said:

Would aerobraking be viable for this mission? I know it wasn't built for it, but a really shallow pass shouldn't pose much of a threat, should it?

They'd have to drop the periapsis far enough first, which takes fuel they may not have (including extra fuel for raising the periapsis again after enough aerobraking). Remember, the main engine is dead, they're already burning RCS fuel for orbital maneuvers here.

[SmartS=true]

Wait, the RCS system has >2 km/s of delta-v?

[Streetwind]

After venting the main propellant tank to make the probe lighter, probably And keep in mind that sending science probes to other planets is expensive and complicated, so those probes usually have RCS propellant budgeted for a decade of stationkeeping or more.

It's true that they've essentially cannibalized most of the probe's lifespan with this maneuver. Akatsuki won't last long now - a year, maybe two? They've probably calculated it somewhere, but I'm too lazy to look it up But it was either this, or no science at all.

[cantab]

7 hours ago, PB666 said:

Judging by the telemetry on the animated live stream and the fact there is a pericytherion in 2'45" i woukd say they have orbital insertion, now all they have to do is lower the apoapsis. 

The mission was always planned for an elliptical orbit, so they don't need to lower it much either.

2 hours ago, SmartS=true said:

Wait, the RCS system has >2 km/s of delta-v?

The main engine is hydrazine/nitrogen tetraoxide bipropellant, while the RCS is hydrazine monoprop. My understanding is they run off the same hydrazine tank, which would mean the RCS can get pretty decent delta-V. And the oxidizer has been dumped.

[Frida Space]

2 hours ago, SmartS=true said:

Wait, the RCS system has >2 km/s of delta-v?

The insertion manoeuvre was less than 1 km/s of DeltaV. However yes, with all the propellant they've dumped (65 kg) it probably has.

2 hours ago, Streetwind said:

Akatsuki won't last long now - a year, maybe two? They've probably calculated it somewhere, but I'm too lazy to look it up  

JAXA says it will last for at least another two Earth years, so that's pretty good!

19 minutes ago, cantab said:

The mission was always planned for an elliptical orbit, so they don't need to lower it much either.

Akatsuki was designed to enter a much lower elliptical orbit, one with a period of 30 hours. Its new orbit (which it hopefully reached yesterday) has a period of 15 days. But in March-April it will be lowered to 9 days.

Edited December 7, 2015 by Frida Space

[PB666]

http://www.nature.com/news/japan-orbiter-seeks-second-shot-at-venus-1.18943
https://spaceflightnow.com/2015/12/06/japanese-space-probe-to-steer-into-orbit-around-venus/

There is more explanatory and graphical information in the links

[YoetoJoe]

Akatsuki successfully enters orbit according to JAXA.

Periapsis: about 400km

Apoapsis: about 440,000km

Inclination: about 3 degrees retrograde

Period: about 13 days and 14 hours

http://global.jaxa.jp/press/2015/12/20151209_akatsuki.html

Edited December 9, 2015 by YoetoJoe

[Frida Space]

We've been following the orbital insertion as it took place on another topic, forum.kerbalspaceprogram.com/index.php?/topic/126766-akatsuki-venus-orbital-insertion 

Edited December 9, 2015 by Frida Space

[Frida Space]

JAXA confirmed Akatsuki achieved target orbit. This image was taken shortly after insertion burn:

[SaturnianBlue]

The actual orbit time is 13 days and 14 hours it seems, 400KmX440,000km orbit. The inclinations is around 3 degrees.

Heres a one micron infrared camera picture from 68,000 kilometers taken at 11:50Pm EST Sunday.

Edited December 9, 2015 by SaturnianBlue

[insert_name]

ever notice that pictures of venus's clouds have a triangular formation towards the equator, why is this

[Findthepin1]

Does it snow CO2 at the high altitudes

[SuperFastJellyfish]

6 minutes ago, insert_name said:

ever notice that pictures of venus's clouds have a triangular formation towards the equator, why is this

I would say that the wind speeds are higher at the equator so they 'drag' the increasing latitudes along with them to some extent.  Just my uninformed opinion. 

Edited December 9, 2015 by SuperFastJellyfish

[PB666]

merge

[Aser]

Anyone know why they're waiting until March to change their orbit? Seems like a long  time.

[Vanamonde]

Threads merged. 

[todofwar]

They actually pulled it off! Hard to believe. This has to be the most Kerbal thing I have ever read happen in real life. 

[fredinno]

On 12/8/2015 at 0:26 PM, Frida Space said:

JAXA confirmed Akatsuki achieved target orbit. This image was taken shortly after insertion burn:

What's up with the black and white camera? What, a colour camera is out of the question for an orbiter?

[HebaruSan]

3 minutes ago, fredinno said:

What's up with the black and white camera? What, a colour camera is out of the question for an orbiter?

All (most?) space cameras are black and white. They put various filters in front of them to get faux color, because that way you get maximum precision and can use the same technique for infrared, etc.

[Frida Space]

1 hour ago, HebaruSan said:

All (most?) space cameras are black and white. They put various filters in front of them to get faux color, because that way you get maximum precision and can use the same technique for infrared, etc.

I think (might be totally wrong) even black and white is a filter. I have some experience using telescopes and black and white is considered a filter by itself ("Luminance" filter). Not sure if the same applies to cameras though.

[todofwar]

On 4/1/2016 at 2:04 PM, Frida Space said:

I think (might be totally wrong) even black and white is a filter. I have some experience using telescopes and black and white is considered a filter by itself ("Luminance" filter). Not sure if the same applies to cameras though.

As a spectroscopist I would say that it makes sense to look at raw photon flux if you want the highest possible resolution. You can then throw on some filters to find out how much of each color is coming through. Colors might be "pretty" but don't actually hold much info. As was pointed out, you can also use specific filters to get UV and IR data this way and get the most bang for your buck. 

[Frida Space]

Great news: first science from Akatsuki! The probe is currently busy lowering its apoapsis to 310,000 km and is scheduled to begin regular observations in mid-April, but some science has already arrived back to Earth and it is definitely tantalizing.

On Dec. 7th, the LIR camera (mid-infrared, 10 micrometres) observed a mysterious bow-shaped structure in the high altitude clouds, spanning both hemispheres. The structure was still visible in images taken 4 days laters. "No similar structure has ever been observed," said Japanese scientists.

On March 4th (and then again on March 25th), the USO experiment observed a radio occultation, meaning Akatsuki passed behind Venus' disk as seen from Earth. Just before disappearing and immediately after reappearing on the other side of the planet, the instrument sent radio waves back to Earth. The waves were filtered through the planet's atmosphere, enabling scientists to reconstruct the temperature profile. The graph is on the right side of the image above, with altitude in km on the y-axis and temperature in K on the x-axis. The blue line represents the data collected at entry, while the red line represents the data collected at egress. The graph on the left is a frequency change graph.

The IR1 camera (1 micrometer) observed the highlands of Aphrodite Terra (the darker regions in the image above) during nighttime. The image was obtained on January 21st from 44,000 km away.

 

On December 9th, the UVI camera (293-365 nanometers) observed Venus three times, with two hours between each image (14:10 - 16:10 - 18:10 UTC). The image allows scientists to measure the winds speed. The spatial resolution is 70 km per pixel.

Seeing these images, I'm so glad Akatsuki managed to reach Venus (and stay, this time). Lacking a Venus orbiter for so long would have been terrible for science!

[Scotius]

Good news indeed. Props for japanese Mission Control for pulling this off  - and in a very kerbal way

[Frida Space]

1 hour ago, Scotius said:

Good news indeed. Props for japanese Mission Control for pulling this off  - and in a very kerbal way

It makes it that much more special for us  plus, the latest reports say the current manouvering capability will allow it to reach 90% of its original science goals... Kerbal is the way to go!

[fredinno]

4 hours ago, Frida Space said:

Great news: first science from Akatsuki! The probe is currently busy lowering its apoapsis to 310,000 km and is scheduled to begin regular observations in mid-April, but some science has already arrived back to Earth and it is definitely tantalizing.

On Dec. 7th, the LIR camera (mid-infrared, 10 micrometres) observed a mysterious bow-shaped structure in the high altitude clouds, spanning both hemispheres. The structure was still visible in images taken 4 days laters. "No similar structure has ever been observed," said Japanese scientists.

On March 4th (and then again on March 25th), the USO experiment observed a radio occultation, meaning Akatsuki passed behind Venus' disk as seen from Earth. Just before disappearing and immediately after reappearing on the other side of the planet, the instrument sent radio waves back to Earth. The waves were filtered through the planet's atmosphere, enabling scientists to reconstruct the temperature profile. The graph is on the right side of the image above, with altitude in km on the y-axis and temperature in K on the x-axis. The blue line represents the data collected at entry, while the red line represents the data collected at egress. The graph on the left is a frequency change graph.

The IR1 camera (1 micrometer) observed the highlands of Aphrodite Terra (the darker regions in the image above) during nighttime. The image was obtained on January 21st from 44,000 km away.

 

On December 9th, the UVI camera (293-365 nanometers) observed Venus three times, with two hours between each image (14:10 - 16:10 - 18:10 UTC). The image allows scientists to measure the winds speed. The spatial resolution is 70 km per pixel.

Seeing these images, I'm so glad Akatsuki managed to reach Venus (and stay, this time). Lacking a Venus orbiter for so long would have been terrible for science!

Is it possible to use aerobraking to reduce the orbit to its originally intended orbit?