Rosetta and OSIRIS-REx

today, as promised I will look upon two missions that has to do a lot with small stuff flying around the Solar System.

Now I said stuff because Rosetta is a mission for comet and OSIRIS is mission for asteroid.

Rosetta is a mission that was launched back in 2004 by ESA which is European organization. It went for the comet 67P or also called Churyumov-Gerasimenko which kinda looks like duck:

Comet 67P on 19 September 2014 NavCam mosaic.jpg

Ok, fine, it does not but look here.. from this photo I would say that it is cat with huge tumor on back.

It went with Philae which is a lander module. It took 10 years to get there. It visited two other asteroids and went around Mars.

After some small changes it went to orbit around the comet even though it has escape velocity of 1 m/s.

Then it deployed Philae in 2014 but harpoons that should have eased the landing did not deploy and the site was much harder than it looked like before (the site was chosen because there was supposed to be “soft” regolith). It bounced twice and almost float away completely. It had battery for 2 days which were of course not enough to conduct all experiments and it could not recharge because it was under some cliff. Nobody knew where it was and we could not identify pictures that it took.

Philae found

It puts me in awe to know that this picture is from a comet. (Philae sits in the right middle of the picture in shadow.)

Luckily Rosetta still orbiting the comet finally found it and put them all in context. The mission ends in 30th September and Rosetta will too crush on the surface.

close up of Philae

The picture of Philae

Now that is for some asteroid exploration back in time.

Three days back, 8th September OSIRIS-REx, an asteroid study and sample return mission was launched.OSIRIS-REx Mission Logo December 2013.svg

The last part is pretty huge, yes USA is for the first time going to return samples from an asteroid to Earth (Utah is the landing site).

It launched on the often used Atlas V and the whole mission for asteorid called Bennu will take 7 years. OSIRIS will stay on its surface for whole 505 days! (Look how planned this whole thing is!)

There are lot of instruments on its board which I wont go through all. There are many cameras because OSIRIS will first orbit the asteroid and scan its surface to find a good place to land.

It has special leg that will try to take samples using gas of nitrogen. It can take up to 2 kilograms and enough nitrogen for three tries.


Moons of our Solar System: Thebe

continuing in the promised series about moons I will today cover the satellite Thebe, this time I even have some “high resolution” pictures so keep on reading!

There are few huge craters on Thebe. (largest is Zethus with diameter of 40 km)

Thebe is another Jupiter‘s moon. It is quite smaller than Amalthea, with 100 kilometers as mean diameter. It was named for Greek nymph, in both stories I found, she was lover of Zeus (yet again) but in one she was also the daughter of Egyptian king.

It is quite similar to Amalthea, again it is tidally locked, which means that one side always turns toward Jupiter (this is also true for Moon). The surface is probably red what you can not see on black and white pictures of course. We can estimate its mass only based on the similarity with Amalthea, the value you will get is roughly 4*10^17 kilograms.

For the first time its image was taken back in 1979 by Voyager. Later, Stephen  P. Synnott found it on one picture. Four years later the name we use was first used.[1]

The fact that it is blurry wont help you much.

The above picture is the first sign of another moon, but watch out, this one is only shadow.

In background you can see some huge storms on Jupiter.

Another picture of Jupiter but this time Thebe is really visible! (Yeah it is not just filth on you monitor).

Finally, Jupiter has faint rings. These rings have to made up of something. Usually rings are created when some rocks are ripped apart by tidal forces. Also they can be fed over long periods of time be debris that leaves some moons.

Thebe has one very faint ring which is created by the second method. It is three times fainter than the ring of Amalthea which is very faint too. It has diameter of 65k-113k kilometers and it is not so thin (8400 km) as the Saturn’s rings which are even only several meters tall.


References: 1) 2) 3) 4) 5) 6) 7)

PS: the second and third pictures were taken from the same site and official permission should be needed only for commercial purposes, which is not me.

[1]S/1979 J 2 was the original name, though I did not decode it it probably means S=satellte 1979=the year it was found J=Jupiter 2=probably second in row with this designation.

Moons of our Solar System: Himalia

it has been about 4 months since I last posted about moons. The last post was about Amalthea (pretty cool name huh?). I thought that maybe I should resume some of the series so lets see how it will go. (its mostly astronomy blog so no wonder that these things are here.)

If I count right, Himalia has 29 pixels!

Last time I was talking about Jupiter’s moons so I will continue with those. Today the topic is Himalia.

As you could guess, this name is connected to Jupiter (Zeus in Greek mythology). Most of the time all the people (moons) are lovers of Zeus and Himalia is no exception, she was the nymph that brought 3 sons to Zeus, those were Spartaios, Kronios and Kytos.

Though I found that she is good for watching I highly doubt this since the apparent magnitude (how bright it is) is only 14.6 which makes it almost as visible as Charon, the moon of Pluto (15.55).

Himalia is the largest irregular satellite of Jupiter. To be irregular satellite means to be formed somewhere else and be captured later on by the planet. Such moon has highly eccentric orbit which is also inclined and even retrograde. She orbits much further from Jupiter than the other moons I talked about. The distance ranges from 11-13 million kilometers! This is one 15th of the distance of Earth to Sun which is quite a lot for a moon!

Since there are many other objects around Jupiter like Galilean moons that are easier to study (also more interesting) not many missions studied this piece of rock. It was discovered on 3rd December of 1904 by Charles Dillon Perrine. We know some things from spectroscopy, it is similar to C-type asteroid which means that it contains minerals with

Not so good either

water though otherwise such an asteroid is pretty dark. While Himalia is small compared to planets, it has masss of 4.19*10^18 [1]. It’s diameter is not very clear because the closest pictures were taken millions of kilometers away. There are basicly two pictures of this moon, one which you can see above is by Cassini-Huygens and second is by New Horizons (on the right).

It was thought that Himalia has something to do with the disappearance of other even smaller moon Dia when it disappeared in 2000. Dia was luckily found in 2010 so Himalia is innocent.


[1] This does not mean that Himalia is heavy in Solar System, Earth has roughly 6*10^24.

Meteor, Meteorite, Meteoroid?

as the title points out I will write today about meteors, meteorites, meteoroids and asteroids. I have to say that before I searched it was not sure which one is which.

Lets start with asteroid.


These things are the largest. You probably know few of them because the biggest are also called minor planets or dwarf planets. There are quite lot of them, the biggest one inside of the orbit of Neptune is Ceres, that is the dwarf planet with these cool bright spots. There are quite few types based on what are they composed of. There are carbonate, silicate and metallic asteroids for example.

Lot of them are also in the Kuiper belt.


This one is a bit tricky. It is smaller asteroid, sometimes just a dust. The important thing is that as well as asteroid it has to be flying in outer space to be itself. Of course there are millions and millions of these objects. Usually they are considered to be smaller than one meter. When such object enters the atmosphere it can be fast as 20 km/s!


Meteor is more often known as “shooting/falling star”. It is just the event when meteoroid enters the atmosphere and heats quickly since as I said it is pretty fast. In some time of the year Earth goes through dust that was left by comets. Those are called meteor showers. When meteor shines bright enough, more than any planet in the night sky, it is considered fireball, which was for example Chelyabinsk meteor.


Meteorite is object that survives the path through atmosphere and impacts Earth (or other object, Mars or Moon for example). Of course quite often these things shatter a lot. People are than trying to find the debris. Also some are quite dangerous and can easily kill person even if they are very small. The largest one piece has stunning 60 tonnes.


Impact on roof