3I/ATLAS

[overgeeked]

Neil deGrasse Tyson did a StarTalk on it. Likely several more by now. He cautioned against people replacing the “god of the gaps” with the “aliens of the gaps.” That is don’t assume aliens just because we don’t know. We don’t know. That’s the point. When we get more evidence, we’ll know more and can make a more educated guess.

 

[Morrus]

I know you're joking and as far as anyone knows it's not "heading for Earth", but the shutdown doesn't explain why ESA's being so slow.

Science be slow sometimes. It’s not a race.

 

[Ryujin]

Science be slow sometimes. It’s not a race.

Indeed. Something about verifying information before making conclusions, or somesuch.

 

[dragoner]

It's a conspiracy! What are they hiding from us?

 

[briggart]

I know you're joking and as far as anyone knows it's not "heading for Earth", but the shutdown doesn't explain why ESA's being so slow.

Maybe I'm missing something, but did ESA announce plans to use Mars Express to look at 3I/ATLAS?

That seems strange, as the spacecraft is designed look down at the planet, not at deep space objects.

Mars Express orbits the planet at a distance between 300 and 10000 km and observes the surface with a resolution ranging between few meters and ~100m, depending on the instruments.

At ~ 29 million km, 3I closest approach to Mars, those instruments would be able to resolve only ~ 100 - 1000 km, while we believe 3I nucleus to be few km across. It doesn't seem to offer a significant improvement over what we already have from HST, JWST, Spherex, etc.

 

[Hriston]

Maybe I'm missing something, but did ESA announce plans to use Mars Express to look at 3I/ATLAS?

That seems strange, as the spacecraft is designed look down at the planet, not at deep space objects.

Mars Express orbits the planet at a distance between 300 and 10000 km and observes the surface with a resolution ranging between few meters and ~100m, depending on the instruments.

At ~ 29 million km, 3I closest approach to Mars, those instruments would be able to resolve only ~ 100 - 1000 km, while we believe 3I nucleus to be few km across. It doesn't seem to offer a significant improvement over what we already have from HST, JWST, Spherex, etc.

This is from an FAQ on ESA's website esa.int:

In the coming months, ESA will turn interplanetary voyagers such as Mars Express, ExoMars Trace Gas Orbiter and the Jupiter Icy Moons Explorer (Juice) in the direction of the comet to make further observations with eyes from all over the Solar System.​

And there's also this:

When and how will ESA’s Mars’s missions observe 3I/ATLAS?

ESA’s Mars Express and ExoMars Trace Gas Orbiter (TGO) will observe the comet with several instruments around its closest approach to Mars on 3 October 2025. On that date, 3I/ATLAS will be around 30 million km from Mars.

The instruments turning their eyes to the comet include Mars Express’s High Resolution Stereo Camera (HRSC) and ExoMars TGO’s Colour and Stereo Surface Imaging System (CaSSIS) – both cameras that are typically used to photograph the Red Planet. We will also attempt to measure the spectrum of light from the comet using Mars Express’s OMEGA and SPICAM spectrometers and TGO’s NOMAD spectrometer, though it is not certain whether the comet and its tail will be bright enough for a full spectral characterisation.

The observations may give us hints about the volatile activity and composition of 3I/ATLAS. As Mars Express and ExoMars TGO are designed to image the martian surface just a few hundred to thousand kilometres below, we do not expect spectacular images of a (relatively) small comet 30 million km away; the comet itself will cover less than a pixel in the images. We expect better images of the halo of gas around the comet and the tail that streams behind it. The success of the observations also depends on how bright the comet is as it approaches the Sun, which in turn depends largely on how much water it contains and how much escapes in the form of a tail.​

Higher resolution images with a pixel size of 30 km should have been captured by the HiRISE camera carried by NASA's Mars Reconnaissance Orbiter, which might be sufficient to determine the object's actual size.

 

[Umbran]

What a coincidence that a large object is heading for Earth ....

It isn't "heading for Earth". It isn't going to come anywhere near Earth. It's closest approach is going to be some 1.8 AU from us - meaning 1.8x the distance between the Earth and the Sun. It is on the other side of the solar system from us!

 

[Umbran]

Maybe I'm missing something, but did ESA announce plans to use Mars Express to look at 3I/ATLAS?

That seems strange, as the spacecraft is designed look down at the planet, not at deep space objects.

Hey. It isn't like they get to pick and choose. We don't get to plan this - the thing showed, up, and we have to use what hardware is available.

At ~ 29 million km, 3I closest approach to Mars, those instruments would be able to resolve only ~ 100 - 1000 km, while we believe 3I nucleus to be few km across. It doesn't seem to offer a significant improvement over what we already have from HST, JWST, Spherex, etc.

Yep. In most pictures we can take, from anywhere, the nucleus is less than one pixel.

That is exactly why we need to take as many pictures as possible, from as many vantage points as possible. When you don't have one really good picture, you squeeze what you can out of may crappy pictures.

 

[Umbran]

It's a conspiracy! What are they hiding from us?

That too many of us are too science illiterate to have any freakin' patience.

 

[Umbran]

That the term has been used isn't in question. It's that it doesn't seem to have a workable definition as a category other than "things which resemble comets", so doesn't shed much light on the nature of this particular object.

Of course not! Because (duh!) - not much light has been shed on it yet!

We use vague categories when we don't know much! The universe, and science, moves at its own pace, not yours.