Editor's note: In addition to having a knack for science communication, Rhett Allain is Associate Professor of Physics at Southeastern Louisiana University. He writes regularly for Wired's Dot Physics blog and is a bit of a physics fanatic who spends more time than many pondering how daily life intersects with science. With the recently announced development of ATV in cooperation with NASA for Orion, we're delighted to feature a few posts from the far side of the Atlantic. Enjoy!
If you want to estimate how many ATV launches it would take to build or supply the Death Star, you first need to know something about a Death Star. I could just make some wild estimates about the Death Star, but I won’t. Instead I will look at two interesting estimations.
Russian mission control has just confirmed that the two cosmonauts have successfully replaced the Laser Radar Reflector (LRR – docking target) located at the aft end of the Russian Service Module. ATV-4 will use this during the Rendezvous phase of its automated docking, set for 15 June.
Helmet cam view of LRR replacement 19 April 2013
REPLAY: ATV laser radar reflector to be replaced during today’s EVA
Today, Expedition 35 spacewalkers Vinogradov & Romanenko will deploy/retrieve scientific experiments and install a replacement navigation aid – the LRR – for ATV-4. Replacement of the LRR is set to happen between 18:00-18:30 CEST.
The Laser Radar Reflector target is used by ATV during the last part of Rendezvous operations. Previous investigations concluded that the current LRR should be replaced as it is likely contaminated.)
We received a query yesterday from Ian Benecken who asked, "Why does it take 10 days for ATV to reach the ISS? Has that something to do with the mass of that ATV?" We sent this query to ESA's lead mission director, Jean-Michel Bois, at ATV-CC, who provided this reply. Thanks, Ian, for your query!
Jean Michel Bois in ATV-CC just prior to launch 16 Feb 2011
The nominal duration from launch to docking is five days to 'phase' or synchronise the orbits of ATV and ISS. This '5-day' strategy allows a standard set of manoeuvres from the orbital injection point (by Ariane at 260km altitude) and the ISS orbit, which is at between 390-410 km, independently of the launch date and of the ISS position on its orbit.
Note that the ATV launch time is set to match when the ISS vertical plane is just passing by Kourou (so phasing concerns only ATV 'up/down' manoeuvres, not 'left/right' – which are very costly in propellant).
Lift-off for ATV Albert Einstein on board Ariane flight VA213 from Kourou is now planned for 5 June 2013. Details later.
Using astronaut Mike Fossum’s YouTube video to measure ATV acceleration
By Rhett Allain
The Automated Transfer Vehicle (ATV) doesn’t just bring supplies to the International Space Station. It can also be used for ISS reboosts. What is a reboost? In short, during a reboost, the ISS velocity is increased by a small amount to bring the space station up to a slightly higher orbit.
Why is this needed? Well, although the ISS is in space, there is still stuff up there (gas from the atmosphere) that exerts a small drag force on the Station, decreases its velocity. The reboost are there just to keep it where it needs to be.
This video shows the inside of the ISS during an ATV reboost, i.e. when the ATV's main thrusters were firing. Let’s see if we can estimate the ATV thrust based on the acceleration of astronauts inside the space station.
Editor's note: In addition to having a knack for science communication, Rhett Allain is Associate Professor of Physics at Southeastern Louisiana University. He writes regularly for Wired's Dot Physics blog and is a bit of a physics fanatic who spends more time than many pondering how daily life intersects with science. With the recently announced development of ATV in cooperation with NASA for Orion, we're delighted to feature a few posts from the far side of the Atlantic. Enjoy! – DGS
There are a couple of different ways you can measure the acceleration in NASA astronaut Mike Fossum's YouTube video, but I am going to use one of the astronauts themselves (we think this is the first scientific use of an astronaut's floating body as seen in a YT video to calculate ATV acceleration – Ed).
Basically, I will use a video analysis program (in this case, the free Tracker Video Analysis). With video analysis, you can get position and time data from each frame of a video. If the motion of the astronauts had been recorded from a side view, position vs. time would obviously be the best choice. As you can see in Mike's video above, however, Mike, astro Satoshi Furukawa and cosmonaut Sergy Volkov are moving away from the camera, so I will measure the angular size of a person.
As things move farther away from a camera, they also appear steadily smaller. Here is a diagram that shows the relationship between angle, size and distance.
If you know the angle theta (θ) and the length of the object, you can find the distance (which I call r) with the formula:
r = L / θ
With this, I can mark a point on each side of one of the receding astronauts as he accelerates away from the camera. With some basic estimations for the angular view of the camera (and size of an astronaut), I get the following plot of distance from the camera for one of the astronauts.
Latest instalment of the mission diary from Charlotte Beskow, deputy ATV mission manager. Note the timeline of this post begins back in February and runs until last week – Ed.
ATV-4 launch: June 2013 i.e. we are still at roughly L - 3 months ATV-5 launch: Early 2014 We are at less than L - 12 months!
14 March 2013 - On board AF 3508 over the Atlantic on my way to Kourou! Here comes a smattering of details and updates, showing you what daily life can be like in this most fascinating of all worlds!
ATV-4 is transporting cargo to the International Space Station!
Fuel for the Russian engines - 860 kg
(Russian) Water for the crew - 570 kg
Air (66 kg) and Oxygen (33 kg) - 99 kg
Fuel for maintaining ISS orbit/reboosts - 2,235 kg
Dry Cargo - 2,506 kg
4 Feb 2013 - Simulation of of mission period launch to docking (LEDOWK)
This was an intensive week. It consisted of a full-scale simulation of launch to docking (LEDOWK, which normally takes ca. 8 days) at ATV-CC in Toulouse, involving the complete flight control team including the technical experts of the EST (Engineering Support Team) from ESTEC. To make it more interesting – and to make sure we are prepared for what might come during the real flight – the trainers worked overtime to put together various contingencies. These were selected based on previous flight experience, known weaknesses in the systems, and the sheer (evil? - Ed) inventiveness of the simulator experts.
Some of the Engineering Support Team (EST) members before the simulation started Credit: ESA/C. Beskow
As a consequence, LEDOWK is not the time to fine-tune your procedures, beef up you knowledge of ATV-CC nor develop working routines for the team. All this is either in place or will have to be dealt with some other time.
The EST are, by definition, called when problems arise. For us it was therefore a bit tricky to prepare a staffing plan that would not give away the planned failures. At the same time, we had to respect working-hour regulations and 'normal manning for the flight'. This led to some bizarre shifts, in which people had to turn up more than once in a given 24-hour period. Some were also on call – no sooner had they dropped into bed than the phone would ring with a call from a colleague in need of some vital info.
In terms of failures, we were not disappointed. The sim team kept us on our toes 24h/24 from Monday afternoon until Friday lunch time. The flight control team next door run regular shifts, whereas our hours changed daily. Add to this the use of simulated ISS time (covering 12 March 08:00 to 17 March 23:00 – with a few gaps – and local time being 2 hours behind (which of course had no relation to the real Toulouse local time) and, in the end, we had little idea of what day or what time it really was.
Part of ESA astronaut Luca Parmitano’s busy schedule in the run up to his Volare mission includes final ATV training and exams. Unlike Luca who has to travel the world for his training, you can try your hand at ATV training from home.
Luca already completed ATV training at the European Astronaut Centre in Cologne, Germany and is qualified for undocking ATV as well as backup crew for docking.
Luca was put under a series of simulations last week to refresh and test his skills together with cosmonaut Oleg Kotov, but this time at the Yuri Gagarin Cosmonaut Centre, Star City in Russia. On a given day up to 11 simulations are run where Luca and Oleg have to work together as operators one and two. In addition Luca conducted many simulations on his own.
The main difference between the sessions in Germany and in Russia according to Luca: “Now everything is in Russian!”. Briefing and debriefing at the European Astronaut Centre are done in English while the simulations are in Russian, in Star City everything is in Russian. The hardware and simulations are the same.
Screenshot of ATV training
During the simulations, ATV is put through the worst possible scenarios to test the operator’s skills to the limit.
Luca explains: “For me, a failure is when the safety of the spacecraft is compromised. During an exam a failure is more restrictive. You might take the right action with the correct result, but a few seconds too late, and your score might not be 100%”
Despite this, when we talked to Luca on Wednesday last week, Oleg and Luca achieved a full success rate. As his exam was this week Luca explained: “Any other result would have been bad news”.
Today at ATV-CC: crucial part of this week’s simulation
This sent in early this AM by ESA's deputy mission manager, Charlotte Beskow - Ed.
The simulation of the complete ATV-4 launch-to-docking mission steps is approaching the most interesting part: rendezvous (RDV) and docking. It has been a very busy 'sim' week with a large number of interesting (and, thankfully, false) 'failures' that have kept all of us awake most hours of the day.
Flight control team at work in ATV-CC during docking simulation 8 Feb 2013. Credit: ESA/C. Beskow
It is now 5:00 CET and everyone is rather tired but this has been a very interesting week; in a few hours it will be over for this Sim.
For the ESA Engineering Support Team (EST), there will be just enough time to head back to the hotel, sleep a few hours, check out, go back for debriefing And then head to the airport...
We are all hoping that the actual flight of ATV Albert Einstein will be much smoother!
EST at ATV-CC 8 Feb 2013 Credit: ESA/C. Beskow
24h/24h launch & docking simulation at ATV-CC
The lights are back on in ATV-CC!!! The 'lights' of the displays on the flight control console workstations, that is...
ESA/CNES mission controllers on console in ATV-CC 22 March 2012 Credit: CNES
After several months of darkness, the lights are back on at ATV-CC. This week the mission operations and engineering support teams are performing a major simulation in the ATV-4 preparation campaign.
Starting this morning, we will simulate a complete launch, orbital phasing (catching up to the ISS), rendezvous and docking, all done in real missions time. This means engineers and mission managers will work shifts 24 hours per day, and – contrary to real life (we hope) – there will be plenty of failures to keep us busy...
The general feeling is one of happy expectation. We know one thing for certain: it will not be a boring week.
ESA's ATV-4 Engineering Support Team (EST) during first full sim for launch 4 February 2013. Credit: ESA/C. Beskow
Since ATV-3, the 'lights' on the console work stations have been off, apart from maintenance and the odd simulation/test; but this week they will be on 24h/day and all the screens will be active.
Times in UTC
6/05 - ATV-4 moves to the BAF for final preparations
8/05 - ESA Operations Readiness Review
20/05 - Late-cargo loading
31/05 - Launch Readiness Review (planned)
5/06 Lift-off VA213 (planned) All dates subject to change