# What is the largest operational artificial satellite?

Inspired by this question, besides the ISS and Tiangong modules, what is the largest operational, artificial, and uninhabited satellite, by either mass or volume?

Let's start with area first. That would probably be Rosetta, with an area of $64\text{ m}^2$. Okay, so how about the most massive? Let's try taking that apart some.

There are two currently existing heavy launch vehicles, the Delta IV Heavy, and the Ariane 5 Heavy. Heavier previous vehicles include the Saturn V, N1, the Space Shuttle, and Energia (Wikipedia). The most massive object will be low in orbit for sure, so let's look to see what LEO missions were launched with these orbiters.

• Saturn V- 12 Apollo missions, 1 Skylab project. All manned, and not in orbit. No candidates.
• Energia- One successful launch, Buran, deorbited and destroyed.
• N1- No candidates.
• Space Shuttle- Most likely the heaviest unmanned object it delivered that is still in orbit is Hubble. Wikipedia says it was 11,100 kg at launch, it's probably grown a fair bit since that time. I'm having a bit of a difficult time figuring out the mass change per servicing mission, but I do know the number of instruments went up over time, let's guess it's around 15,000 kg now.
• Delta IV Heavy- Primarily classified US missions. The latest launch is a likely candidate. The mass would have to be more than the Medium, so it's mass is between 13.5 and 23 metric tons, most likely.
• Ariane 5- Heaviest I can find is the Albert Einstein ATV, launched to the ISS but unmanned, 21 metric tons of payload. Of course, that being destroyed, and all ATVs, the largest operational would probably be a GEO satellite, the largest just over 10 metric tons.

So, take your guess among these which is the most massive payload. My guess is some Delta IV heavy launched classified payload, the exact mass of which wouldn't be known. Or maybe Hubble.

As @Tildalwave mentioned, most likely the largest by volume is the spend S-IVB stages of the Saturn 5, with a whopping $326\text{ m}^3$ volume.

• Why do you choose the Albert Einstein ATV? It is no longer in orbit. Dec 19, 2015 at 11:35
• Fair point. I've edited my answer accordingly. Dec 19, 2015 at 11:41
• @PearsonArtPhoto Interesting assessment overall though I don't think Rosetta is particuarly special in terms of area. There are plenty of comsats with 5 or 6 panels per solar array wing and some with some large antennas too. As an aside, I think you've taken the solar array area only. I wonder even if Milstar 1/2 might be larger. Ok, I will go looking for a reference! Dec 20, 2015 at 0:33
• Here: globalsecurity.org/jhtml/jframe.html#http://… and here for human scale claudelafleur.qc.ca/images/milstar6.jpg The first link suggest dimensions, converting to metric gives the solar arrays, two each at about 15m x 3m, and the body, 15m x 1 = 105m2 (I guessed the 1m to make the arithmetic easy). All a bit shaky but it agrees with this for the solar arrays (see table at end) ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19920017652.pdf Dec 20, 2015 at 16:49
• and here, prior to launch, spaceflightnow.com/titan/b41/images/milstar4ontitan1.jpg , I always thought it quite a curious machine Dec 20, 2015 at 16:50

Probably the biggest artificial satellite is a military satellite with classified specs.

The Hubble Space Telescope with 11.000 kg of mass and Envisat with 8.000 kg are probably the on the league of the biggest satellites in orbit.

And responding to the comment above... ... roseta is not a satellite because it is not technically orbiting anything, so it is a spacecraft but not a satellite.

• Um...are you a little behind on the news? Rosetta is orbiting 67P, so it would be a satellite of that comet. May 20, 2016 at 13:59
• to out-pedant you: Rosetta has been alternating between being in orbit of 67P and not being in orbit (not gravitationally bound) with altitudes varying between 10 km and 1000 km... ;P May 20, 2016 at 14:41
• @Hobbes And currently it is likely gravitationally bound: planetgate.mps.mpg.de/Image_of_the_Day/public/… ;) May 20, 2016 at 18:33