Evaluations into solar array tear and Discovery’s MMOD strike

by Chris Bergin

NASA are evaluating a tear in the P6 4B solar array, after Flight Day 8’s efforts to deploy the panels on the relocated P6 truss.

At the same time, engineers on the ground are looking into indications that Discovery suffered a large MMOD (micrometeoroid/orbiting debris) strike to her port wing this morning. It is not known, but likely, that the strike was still not strong enough to cause any damage to the orbiter.

**The most comprehensive collection of Shuttle, Ares, Orion and ISS related presentations and mission documentation, plus expansive daily processing documentation and updates are available to download on L2 **

Extensive STS-120 Special Section on L2, including Flight Plans, ALL Handbooks and Checklists, Manuals, documentation and presentations. STS-122 to STS-127 documentation already available.

STS-120 L2 Special includes over 1600mb of presentations, over 45 Flight Data Files, Manuals, Memos and Exclusive Hi Res Images and video – the most expansive overview of the mission. **Click here for sample**

L2 FLIGHT DAY LIVE: MER/MOD/MMT Live Updates (live console updates, live MMT presentations, for every flight day)

**LIVE updates on Discovery STS-120 FLIGHT DAYS**


MMOD strike:

Listed as ‘triple the maximum ever observed,’ the indication came via the orbiter’s Wing Leading Edge (WLE) sensors. However, previous MMOD strikes that have registered in the WLE system have – for the most part – not even been strikes, such are the sensitivity of the sensors.

‘Reported to us (NASA SE&I) at 7am: Imagery WLE reported a significant hit on the port panel 1. This hit was triple the max ever observed,’ noted official NASA notes during Flight Day 8.

The ‘impact’ registered 2.74 GMRS on the sensors, which is understood to be below the point of concern for engineers. However, it will be checked out during the post-undocking Late Inspection, via the OBBS (Orbiter Boom Sensor System).

‘2 new indications (Panel 1L, 2.74 GRMS; Panel 6L/7L, 0.95 GRMS), 7 total on-orbit indications (6 remain to be cleared by Late Inspection),’ noted Flight Day 8 MMT (Mission Management Team) information.

More news on this issue will be updated when it is available.

P6 4B Array problem:

The Flight Day 8 tasks of P6 2B SAW (Solar Array Wing) redeploy; and P6 4B SAW redeploy, came at the end of a successful seven hour EVA, which aided the relocation of the P6 truss.

The EVA included the additional task of inspecting the port SARJ (Solar Alpha Rotary Joint) – after EVA-2 noted metallic shavings in the starboard SARJ.

The port machinery were found to be in perfect condition, which imagery of the sun tracking motor being downloaded to engineers on the ground for a closer look.

Once the call was made to deploy the arrays on P6, 2B proved to be no issue. However, around 25 bays into the deployment, a tear was seen in one of the panels, causing the deployment to be halted immediately.

The array was rotated, to allow for a full set of imagery to be taken, with this now heading for evaluation on the ground. The array was retracted by a couple of bays to remove tension, with the current plan to leave it ‘as is’ overnight, while NASA check into their options.

The 2.5 foot tear in the array looks worse than it actually is, with the ISS happy that the array is generating power, to the point that it is only under-performing by three percent, compared with its undamaged neighbor.

‘We’re good for all the ops we have planned. We’re tracking the sun from a beta perspective, and we’re in a very good configuration to sort this problem out,’ said ISS program manager Mike Suffredini. ‘All we need out of the arrays is power. Doesn’t need to look good, we just need the power.

‘This will take time, and needs to be worked. But we have time and we can be methodical. Our first job is to get back into what we call a normal configuration.’

Shuttle ready to support ISS:

Yesterday, shuttle manager Wayne Hale spoke about how ‘extraordinarily well’ the mission was proceedings, as they push towards a successful conclusion, and turnaround to the next flight, STS-122.

‘STS-120 Mission going extraordinarily well. Very few funnies. Most things seen we understand and should be able to treat well to get ready for STS-122 launch. We’re fortunate the whole system has worked as well as it has, due to hard work and vigilance of thousands around the Program,’ said Hale at the latest Shuttle Stand-up/Integration meeting. ‘Everyone who helped should be proud the system is working so well.’

**(NOW INCLUDES STS-118 Re-Entry Video) Ride home through the fire, sparks and plasma of re-entry with Atlantis, Discovery and Endeavour. FIVE Stunning high quality 2hr, 355-400mb Camcorder and HUD videos – from payload bay closure – through re-entry with a astronaut held camcorder video – to post landing – several more videos showing landing from 90,000 ft also available – Now includes HALO II Re-entry video**

One again, Hale emphasized how complex this mission is, and that the shuttle program will support the issues the ISS has with its power generating panels – as they will now the new issue on P6.

‘This flight is one of the most complex in Space Station assembly. It is the flight we’ve been working up to that is very hard and very difficult to carry out.

‘Over the weekend the crew looked at the SARJ on the ISS, which has been experiencing some anomalies. They found metal shavings in that joint. It is great that it was found, and that the Shuttle team is there with the resources it brings.

‘We need to understand that the critical spacing between landing STS-120 and launching STS-122 is the on orbit work on orbit on ISS. Are in great position to be ready early to fly on December 6, 2007 (may have to take a day or two delay on that based on what happens on orbit). Will let you know what decisions are. We are here to support assembly of ISS.’

See live threads for up-to-the-second live coverage.

L2 members: All documentation and quotes – from which the above article has quoted snippets – is available in full in the related L2 sections, updated live.

**STARLIGHT: NEW STS-117 MISSION REVIEW MUSIC VIDEO** – STS-118 Mission review video also available. 

(Video section is FREE, but you need to sign up as a member of the forum to enter the video section of the site. We only use your e-mail to send you your password. It will not be used for spam etc.)

Related Articles