LightSail 2 reentry prediction
The air density (the most significant unknown in determining the reentry date) is calculated by means of NRLMSISE-00 atmosphere model along with two data files for the current and predicted solar and geomagnetic indices. Please, see here for the current value and short range prediction of the solar and geomagnetic indices and here for the long range prediction.
Simulation date: 2021-10-23
The initial state of the satellite has been calculated using the following TLEs: .
Reentry date: 2023-01-15 (averaged the 10 TLEs)
Best fit average ballistic coefficient: 0.67 kg/m2
NRLMSISE-00 data files: "SW-All.txt" updated 2021 Oct 23 12:40:00.00 UTC, "oct2021f10_prd.txt" updated 08 October 2021
Gravity model: SGG-UGM-2 truncated to degree and order 15
According to the site LightSail 2 - Mission Control, the spacecraft is currently in the "Solar Sailing" attitude control mode which means that "The spacecraft is attempting to raise its orbit using the solar sail. To do this, it must make two 90-degree turns each orbit. When flying towards the Sun, the sail orients itself edge-on, effectively turning off the thrust. When flying away from the Sun, the sail turns broadside to the Sun's rays and gets a slight push." (see the page "See the Latest Data from LightSail 2 on Our New Mission Control Dashboard").
That is probably the reason why the spacecraft is at a higher altitude than the one obtained from the previous simulation.
The graph shows the predicted minimum, mean and maximum radius vector scaled to a reference sphere with radius of 6371 km (just to show an approximate altitude), but when the instantaneous radius vector drops below 125 km, the blue plot no longer shows the mean radius vector (or semi-major axis), it shows the instantaneous radius vector. The popup label shows the terrestrial time, the radius vector (km) and the inertial speed (m/s).
Simulation date: 2021-04-05
The initial state of the satellite has been calculated using the following TLEs: .
Reentry date: 2022-07-14.7 (averaged the 5 TLEs)
Best fit average ballistic coefficient: 0.56 kg/m2
NRLMSISE-00 data files: "SW-All.txt" updated 2021 Apr 05 12:45:16 UTC, "mar2021f10_prd.txt" updated 12 March 2021
Gravity model: SGG-UGM-1 truncated to degree and order 15
The graph shows the predicted minimum, mean and maximum radius vector scaled to a reference sphere with radius of 6371 km (just to show an approximate altitude), but when the instantaneous radius vector drops below 125 km, the blue plot no longer shows the mean radius vector (or semi-major axis), it shows the instantaneous radius vector. The popup label shows the terrestrial time, the radius vector (km) and the inertial speed (m/s).