Starship Asterisk*

Camiel wrote:Seems very unlikely that (late) Herschel has taken the picture last month! :^)

Wikipedia wrote:Friedrich Wilhelm Herschel (15 November 1738 – 25 August 1822) was a British astronomer and composer of German and Czech-Jewish origin, and brother of fellow astronomer Caroline Herschel, with whom he worked. […] On 11 February 1800, Herschel was testing filters for the sun so he could observe sun spots. When using a red filter he found there was a lot of heat produced. Herschel discovered infrared radiation in sunlight by passing it through a prism and holding a thermometer just beyond the red end of the visible spectrum. This thermometer was meant to be a control to measure the ambient air temperature in the room. He was shocked when it showed a higher temperature than the visible spectrum. Further experimentation led to Herschel's conclusion that there must be an invisible form of light beyond the visible spectrum.

ESA wrote:The Herschel Space Observatory was launched on 14 May 2009 and observed the sky for almost four years, until its coolant ran out on 29 April 2013.

BDanielMayfield wrote:So, since this is an infrared image, what we are seeing here is warm gas or dust of various temperatures regardless of composition, or do the different colors show areas of different elements?

Chris Peterson wrote:

BDanielMayfield wrote:So, since this is an infrared image, what we are seeing here is warm gas or dust of various temperatures regardless of composition, or do the different colors show areas of different elements?

At these long wavelengths (70 μm and 100 μm) we're just seeing the thermal emissions of cool dust (30-40 K). I don't think we can infer anything about composition.

RJN wrote:I apologize for not keeping better track of Herschel's status, and for the oversight in the APOD text.

Chris Peterson wrote:

RJN wrote:I apologize for not keeping better track of Herschel's status, and for the oversight in the APOD text.

It is a positive sign of our times that there are so many space-based observatories now that keeping track of them all has become a significant chore!

Ann wrote:

MarkBour wrote:

Chris Peterson wrote: It is a positive sign of our times that there are so many space-based observatories now that keeping track of them all has become a significant chore!

Agreed! On the downside, though, I wonder will there come a day when we will need a rule, such as: "You can't launch another unless you fetch and return one."

Good idea. Otherwise we might not be able to see the Universe for all the space junk orbiting in front of it.

Chris Peterson wrote:
It's going to be a long time before space observatories are numerous enough to become a significant part of the space junk problem!

https://en.wikipedia.org/wiki/Herschel_Space_Observatory wrote:
<<The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was the largest infrared telescope ever launched, carrying a 3.5-metre mirror and instruments sensitive to the far infrared and submillimetre wavebands (55–672 µm). The observatory was carried into orbit in May 2009, reaching the second Lagrangian point (L2) of the Earth–Sun system about two months later.

On 29 April 2013, ESA announced that Herschel's supply of liquid helium, used to cool the instruments and detectors on board, had been depleted, thus ending its mission. At the time of the announcement, Herschel was approximately 1.5 million km from Earth. Because Herschel's orbit at the L2 point is unstable, ESA wanted to guide the craft on a known trajectory. ESA managers considered two options:

• 1. Place Herschel into a Heliocentric orbit where it would not encounter Earth for at least several hundred years.
  2. Guide Herschel on a course toward the Moon for a destructive high-speed collision that would help in the search for water at a lunar pole. Herschel would take about 100 days to reach the Moon.

The managers chose the first option because it was less costly.

On 17 June 2013, Herschel was fully deactivated, with its fuel tanks forcibly depleted and the onboard computer programmed to cease communications with Earth. The final command, which severed communications, was sent from European Space Operations Centre (ESOC) at 12:25 UTC. The mission's post-operations phase will continue until 2017. The main tasks are consolidation and refinement of instrument calibration, to improve data quality, and data processing, to create a body of scientifically validated data.>>

MargaritaMc wrote:
JPL did a nice resumé of the achievements of the Herschel Space Observatory

https://www.jpl.nasa.gov/news/news.php?feature=6952
SEPTEMBER 22, 2017
Legacy of Herschel Space Observatory

neufer wrote:

MargaritaMc wrote:
JPL did a nice resumé of the achievements of the Herschel Space Observatory

https://www.jpl.nasa.gov/news/news.php?feature=6952
SEPTEMBER 22, 2017
Legacy of Herschel Space Observatory

Assuming that Planet 9 is internally heated like Neptune and is running a temperature ~50 K
HSO might have been useful in the current search by making use of ~60 micrometer IR.

MargaritaMc wrote: The Planet Nine temperature estimate by Linder et al* is 47K, so the Herschel Space Observatory might indeed have been useful...

Click to view full size image

*E. F. Linder et al. Evolution and magnitudes of candidate planet nine, Astronomy & Astrophysics (2016). DOI: 10.1051/0004-6361/201628350
https://www.aanda.org/articles/aa/abs/2 ... 50-16.html

https://m.phys.org/news/2016-04-planet.html

BDanielMayfield wrote:
It's ironic that so much is known about an unknown planet.

Chris Peterson wrote:

Ann wrote:

MarkBour wrote: Agreed! On the downside, though, I wonder will there come a day when we will need a rule, such as: "You can't launch another unless you fetch and return one."

Good idea. Otherwise we might not be able to see the Universe for all the space junk orbiting in front of it.

It's going to be a long time before space observatories are numerous enough to become a significant part of the space junk problem!