Talk:SMART-1

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[edit] Xenon fuel

When it says "The onboard fuel reserve amounts to just 60 litres (about 16 gallons) of inert xenon, with a mass of 80 kg" I presume this is liquid (from the weight given). Can anyone confirm this, and if so I just thought it was worth mentioning.

Also is the Xenon strictly speaking a fuel? It is not powering the engine - isn't it a propellant? CharlesC 19:53, 15 December 2005 (UTC)

Changed "fuel" to "propellant," good catch! Don't know about the other question, will have to check. Awolf002 20:27, 15 December 2005 (UTC)
Ion thrusters traditionally work with gas state, I doubt SMART's thruster works differently. In addition, xenon has a very low boiling point (-108.12 °C, -162.62 °F), impossible to keep for all the duration of the mission (AFAIK, payload fairing is at room temperature at the moment of launch) // Duccio (write me) 22:26, 24 August 2006 (UTC)

My guess is it would be pressurized and boil off would be used for propellant. Xenon is heavy so makes an ideal propellant for transferring energy to motion. Big question is who took the best pictures of it's demize yesterday? —The preceding unsigned comment was added by 70.132.4.53 (talk • contribs) 17:05, 3 September 2006 (UTC).

I would have guessed a boiling-off liquid storage as well (simple, high energy storage with a constant nozzle pressure - like a propane burner on a tank of liquid propane). When I tried to figure it out, however, I ran into a mystery. If the tank truly is 60 litres with a mass of (assuming Xe only in mass) 80kg, that means the Xe in the tank has a density of 1330 g/litre, versus 5.89 g/litre at STP. Liquid Xe has a density of 3000 g/litre so in the tank it must be a gas, right? But at that compression of density (1330 mg/cm3), the pressure would be 226 atmospheres, while according to this phase diagram, Xe would have to be a liquid at this pressure and any reasonable temperature (eg: liquification at c.45atm at 0˚C or 10atm at -40˚C). Any ideas?132.204.195.69 22:57, 3 September 2006 (UTC)
Just saw that diagram: did you get there from http://en.wikipedia.org/wiki/Xenon? I think that image is incorrectly linked, it does not refer to Xenon (look at the URL: http://science.nasa.gov/headlines/y2002/images/elastic_fluids/critpoint_med.jpg) - I'll remove that link, let's use http://www.webelements.com/webelements/elements/text/Xe/index.html as a reference. // Duccio (write me) 09:02, 4 September 2006 (UTC)

[edit] Images of the impact

Perhaps these could be added using {{noncommercial-ESA}}? http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=39962 // Duccio (write me) 17:33, 3 September 2006 (UTC)

Those images are tagged as copyright CFHT (Canada-France-Hawaii Telescope); would probably need to look into their policies, not ESA.132.204.195.69 19:04, 3 September 2006 (UTC)
Right here:[1]

"You can freely use these pictures for your own personal use. Note, however, that "personal use" does not include the use of pictures on a personal web site if that web site is open to the general public. In such case, we however encourage the use of our material as long as we are first consulted and informed of its use and our copyright is acknowledged in a legible manner. Please also include a link to the CFHT's Hawaiian Starlight main web site." Last two things in that list can easily be done. The rest seems to be just telling them that it's here. Looks good.--Planetary 04:34, 4 September 2006 (UTC)

Also: looks like there's already one of their images on Wikipedia.[2]--Planetary 04:37, 4 September 2006 (UTC)

[edit] One shot

Someone has found good to delete the line about the fact that there is no further mission to the Moon foreseen by ESA. I think that the fact that this mission has no continuation or posterity whatsover is an interesting fact. Further exploration of the Moon will be performed by the US and the space powers from Asia. But not Europe. Hektor 07:15, 4 September 2006 (UTC)

[edit] Nobody objected to selenial 9/11?

Were there any protests? I mean it is not polite to crash into your home without asking first. Also, mankind should not use the Moon as a junkyard, there is already enough soviet Luna and american Apollo iron scrap left up there. Look at the Himalya, mountain climbing expeditions littered the landscape with compressed air bottles, damaged tents, corpses etc. That should not happen to the Moon. 195.70.32.136 07:35, 4 September 2006 (UTC)

Nevermind. You seem to be a troll, judging from a look at your history.--Planetary 04:33, 5 September 2006 (UTC)

[edit] PELs

I wonder about "surrounded by craters in eternal darkness", I don't see that it follows, or is even likely. Rich Farmbrough, 08:46 4 September 2006 (GMT).

It is likely, as Luna's inclination to ecliptic is small (some 5°). By the way, what's PELs for? // Duccio (write me) 15:25, 4 September 2006 (UTC)

[edit] Apollo 11 Landing Sight?

I wonder. did the SMART-1 Catch an image of the Apollo 11 landing sight?

Nope, resolution wasn't good enough. A previous spacecraft did, however (Apollo 15)[3]. The Clementine mission spotted it in 2001.--Planetary 04:31, 5 September 2006 (UTC)

[edit] 68 Nm thrust?

Surely you mean 68mN? - which would fit with mass = 367kg and acceleration of 0.2 mm/s²

[edit] Today's news: "Space probe crashes deliberately on the moon."

I had to read the title twice.

The European Space Agency's SMART-1 satellite successfully completes its mission by deliberately crashing onto the Moon.

isn't that like, a NASA first? :D :D :D

Project2501a 20:49, 5 September 2006 (UTC)

Not at all. Many things end their mission by colliding with something. Look at the Luna program which went on for almost 30 years. In those days there weren't any fancy things like changing trajectory, the direction you launched was the direction you went. The Ranger program as well. Definently not a NASA first. (This is the first time for ESA, though.)--Planetary 21:19, 5 September 2006 (UTC)

[edit] Delta-v units

The units given after the term "delta-v" are m/s (meters per second) these are not units for acceleration, I changed this to m/s² assuming it was a typo but it was changed back. Could someone please explain or correct this.

Delta-v (Δv) is a change in velocity. Δ is commonly used to denote a difference. And v is - of course - velocity. The engine thrust is what causes an acceleration. But the sentence in question mentions that 1kg of propellant was used to cause a δv - a change of velocity - of 45 m/s and this is indeed correct since the thrust of the engine goes not change with the amount of used propellant. --J-Star 07:53, 7 September 2006 (UTC)
Δv is NOT acceleration, it's the change in speed irrespective of time. Acceleration, a, is \frac{dv}{dt} - the derivative of velocity with respect to time. When simply discussing Δv, the same units as for v are used. siafu 13:34, 7 September 2006 (UTC)

[edit] Calcium

Why is it notable that Smart-1 detected calcium on the Moon? Didn't Lunar Prospector do that in 1998? The Smart-1 "discovery" was reported in the media, a Google search tells me; but there really isn't any new information at all! I'm removing it from the "Important Events and Discoveries" section.--Planetary 06:53, 23 December 2006 (UTC)

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