Showing posts with label art satellite. Show all posts
Showing posts with label art satellite. Show all posts

Sunday, 5 May 2019

Orbital Reflector has joined the Dark Side

image: Nevada Museum of Art

Orbital Reflector will not shine brightly in our night sky. The extraordinary Art project by Trevor Paglen and the Nevada Museum of Art (see my earlier post here) has run on the cliffs of American politics, and was sadly lost as a result.

In a May 1 press announcement by the Nevada Museum of Art, it was indicated that contact with the satellite has been lost, so the command to inflate the balloon can no longer be sent.

That command should have been sent weeks ago, but was postponed because of, basically, the childish state of US politics. The satellite operators needed to have FCC approval to inflate the balloon: approval that should have been given after enough space had been created between the various payloads of the SSO-A launch.

But then, as the Nevada Museum of Art press release puts it:

"two unanticipated events occurred: 1) Due to the unprecedented number of satellites on the rocket, the U.S. Air Force was unable to distinguish between them and could not assign tracking numbers to many of the them. Without a tracking number to verify location and position, the FCC could not give approval for inflation; and 2) The FCC was unavailable to move forward quickly due to the U.S. government shutdown."

The US Government shutdown referred to was the US Federal shutdown imposed by President Trump, when US Congress did not agree to his proposed spending bill for 2019 (notably, the demand for $5.7 billion in funding for his proposed Border Wall). The shutdown lasted until the end of January 2019 (the longest Federal shutdown ever) and affected the functioning of several Federal agencies including the FCC.

As Trevor himself put it recently:

"We needed to coordinate with the FCC to deploy the reflector, but there was no one to take our calls: there was no government".

In the weeks immediately after the SSO-A launch, the Orbital Reflector operators were in radio contact with the satellite. But over time, the radio pings became weaker and by the time the Federal shutdown was finally over and the FCC had resumed functioning again, the radio of Orbital Reflector had fallen silent.

I am very sad about this outcome. I had looked forward to observing and tracking Orbital Reflector, both to admire it as an unusual global piece of art, and to see how its orbital evolution over time would (or would not) match my earlier modelling. I am also sad because I know how much time, energy and thought Trevor, who is a personal friend, has put into this art project, one of his most challenging so far. It is a pitty it worked out this way, even more so because it happened just because of petty US politics, not flaws in the concept.

But even though the original plan was ruined due to a President that was trying to blackmail Congress into submission, Orbital Reflector still serves a goal. One of the goals of Orbital Reflector, besides being seen, was to trigger debate about who owns space, what does and does not belong there, and who gets to decide about that. That debate certainly happened around Orbital Reflector (see a previous post). In that sense, Orbital reflector was a success.

I also like how Orbital Reflector, which was meant to be the very opposite of the dark shady, anonymous and unseen use of space by the military, now has joined the Dark Side itself: unseen, but there, orbiting in anonymity, and in this state as a result of geopolitical power play the effects of which reach all the way into space.

In a way, Orbital Reflector now has become a symbol of how geopolitical powerplay corrupts everything, even Space, which in a  way was the very thing it was intended to make people think about. That's art for you, even if this developed in a way that was not quite foreseen.

Friday, 23 March 2018

The reentry of Humanity Star (updated)

(This post was updated April 4, 2018, with the results of lifetime-modelling. The update is at the end of the post)


The Humanity Star. Image: Rocket Labs

The Humanity Star reentered into the atmosphere yesterday, 22 March 2018, near 13:15 UT.

Humanity Star (2018-010F) was a surprise payload launched on 21 January 2018 as part of the first successful orbital flight of fledgeling New Zealand space company Rocket Lab's Electron rocket. In addition to three cubesats, the launch featured an unannounced surprise in that it brought a 3-feet, 10.4 kg geodesic sphere into a 530 x 295 km, 82.9 degree inclined Polar orbit.

The idea was that the reflective surfaces would produce a conspicuous flashing object that would attract people's attention so that they would look up at the sky and ponder their place in the Universe. As a non-functional "art-for-arts-sake" satellite, it scooped (and was perhaps inspired by) a similar but much better thought through project by Trevor Paglen that is to be launched in August 2018.

Rocket Lab claimed that the Humanity Star would be visible as a very bright object in the sky. In reality, very few people have seen it. It mostly stayed faint, producing occasional very brief bright flashes (I saw one of these myself, at magnitude -1). Moreover, during the first 1.5 months of being on orbit, it stayed in Earth shadow, only becoming visible in twilight in March, when it already was close to reentry. The visibility window hence was short. As a project to attract public attention to the night sky, it largely failed. And the fuzz made by some astronomers about Humanity Star being "sky vandalism", clearly was over the top (and was in fact somewhat ridiculous from the start. Some people appear to take issue with everything nowadays).

Rocket Lab claimed the object would stay on orbit and be visible for nine months. Apparently, they had not realized that the area-to-mass ratio of this object was much different from a usual payload (it was a carbon sphere very lightweight for its size) and apparently they did not seriously model the lifetime. Because in reality, it lasted not nine months but only 60 days, a mere two months, on orbit. The orbital decay was very fast:

Apogee and perigee of Humanity Star over time. Click diagram to enlarge
I have modelled the last few days of Humanity Star's existence, producing reentry estimates in the two days leading to the reentry. I used two methods: one was the combination of Alan Pickup's SatAna and SatEvo software; the other was a simulation in GMAT.


click map to enlarge

The reentry occured in the early afternoon (UT) of  March 22, somewhere along the white line in the map above, and most likely near the two locations marked halfway that line, i.e. over southwest Asia.

JSpOC issued a final TIP bulletin estimating reentry at 13:15 UT  ± 29 min, nominally near 14 N, 61.8 E. My final GMAT simulation gives a result very close to that time and location, at 13:12 UT ± 45 min, nominally near 10.8 N, 61.9 E.

The final SatAna/Satevo result appears to be a bit early (indicating that I have to adjust some settings), placing reentry near 12:07 UT ± 28 min, nominally near 72 N, 126.5 W. For the upcoming Tiangong-1 reentry (see my daily updated post with reentry estimates) I am going to work with revised SatAna/SatEvo settings from now on.

UPDATE added 4 April 2018

I wrote: "apparently they [Rocket Lab] did not seriously model the lifetime".

To emphasize this, I ran a GMAT model for Humanity Star today, to see what modelled orbital lifetime would result.

I used the MSISE90 model atmosphere, a low solar activity regime, and modelled for a mass of 8.16 kg and diameter of 0.91 meter. Starting point was a TLE from 4 days after the launch.

The resulting lifetime was 51 days. My model has it reenter on March 13.
The real lifetime was 60 days. The real reentry was on March 22.

So my modelling resulted in a lifetime that was 85% of the real lifetime, which is not bad for modelling over a 2-month period.

[later added section] 
There are also other values for Humanity Star floating around: a mass of 10.34 kg and diameter of about 1 meter.

Running the model with those figures ads 2 days to the orbital lifetime, i.e. brings it at 53 days, i.e. 89% of the real lifetime.
[end of added section]

It also shows that applying a model (like GMAT) would have yielded Rocket Lab a much more realistic orbital lifetime than the 9 months which they claimed.

click diagram to enlarge