Thursday 30 July - NASA-JPL A perfect launch and Perseverance is on her way to the Red Planet

Note: there are likely to be quite a lot of these sort of posts in the coming months, primarily as a personal record of this important mission. My name being on one of the chips attached to Perseverance adds another dimension of course. I've already signed up to the next part of the mission in 2026 (and Lynne is coming with me!) - The Mars Sample Return Campaign, but more of that much later on. I hope some readers will find something of interest here, but I've not given up on the walking posts!



           
   

ULA's Atlas V-541 lifts off at 7.50am  (EDL) on 30 July carrying the Mars Rover 2020, Perseverance  

The whole event was streamed on NASA's YouTube Channel covering the launch and the rover's separation from the upper stage of the Atlas V to begin its six and a half month voyage to Mars. It's the best viewing I've had in years with interviews with the many engineers and scientists involved and presented by Dr Moo Cooper of JPL and Derrol Nail, Space Coast reporter, two of the most enthusiastic presenters you could hope for.

The upper stage's Centaur engine initially placed the 2020 rover into a parking orbit around Earth at T+ 0:11:27:9 then, after a 33 minute coast over the Atlantic and crossing South Africa, the Centaur re-ignited its RL-10C-1 engine, shutting down at T + 0:52:50:1. The burn, lasting almost 8 minutes accelerated the Mars 2020 spacecraft to escape velocity.

After reaching 24,785mph, the Centaur upper stage shut down and re-orientated itself into the position for release of the spacecraft. At T+ 0:57:32.8 Perseverance, enclosed in its aeroshell, separated from the Centaur upper stage over Indonesia. Twenty minutes later the first signals from the spacecraft were expected through a NASA tracking station in Canberra, Australia. Navigation data indicated that Perseverance was perfectly on course.

During the post-launch press briefing a couple of issues came to light:

First, the proximity of the space craft to Earth was saturating the ground station receivers of NASA's Deep Space Network which are tuned to receive faint signals from deep space. The receivers were therefore detuned and the antennas pointed slightly off-target from Perseverance thus bringing the signal within acceptable range. Telemetry (detailed data from the spacecraft) was restored. (See Tweet from Perseverance)

Secondly, data indicated that the spacecraft had entered safe mode as it passed over the night side of the Earth, a period known as an eclipse, becoming a bit colder than expected. All but essential systems turned off and safe mode was entered. The spacecraft is designed to put itself in safe mode if onboard computers detect that conditions are not within set parameters. 

NASA later said that the temperature disparity was in the liquid freon coolant loop, which dissipates heat from the centre of the spacecraft through radiators on the module carrying the rover to Mars. Modelling by the team at JPL predicted that this might happen but it was not possible to create the exact environment for pre-launch tests and no flight data from Curiosity Rover, launched in November 2011, was available since its trajectory did not include an eclipse.

Programmers had therefore set tight limits on key spacecraft parameters before launch and the cold conditions probably tripped a preset limit. Better a spacecraft go into safe mode, a stable and acceptable mode even when not required, than fail to do so when critical. It's not a problem and controllers tested then sent commands to bring the spacecraft back to nominal flight operations. 

Now on its interplanetary cruise, with several Trajectory Correction Manoeuvers (TCMs) along the way, the next stop is Jezero Crater. 

There may be many things wrong in the USA at the moment (they are not alone), but NASA's space programme, whether involving human or robotic exploration, is not one of them. 

Thanks to NASA-JPL for a superb broadcast and an inspirational endeavour. Go Perseverance!!

Animation : Centaur engine burn 2 (courtesy spaceflight.com) and for the Timeline

Module carrying Perseverance separates from Centaur upper stage (courtesy spaceflight.com)

Courtesy NASA

Perseverance and Ingenuity helicopter being enclosed in the aeroshell which will carry it safely to the Red Planet. (Courtesy NASA-JPL Caltech)

The name plate on board Perseverance - three chips top left

A tweet from Perseverance!

The Control Centre at JPL

Thanks to NASA-JPL's, Mars 2020 Deputy Project Manager, Matt Wallace for providing details of the 'issues' encountered by Perseverance and to Stephen Clark at spaceflightnow.com for the timeline.