Discovery set for triumphant return

by Chris Bergin

Shuttle orbiter Discovery and her seven crew members are enjoying their final hours on orbit, ahead of Friday’s return to Earth.

In what will mark the end to a superb STS-116 mission, the only remaining question is where Discovery will land, with White Sands Space Harbor still favorite, as full scale operations are mobilized to aid what could be up to a two month stay in New Mexico.

**Over 2300mb of STS-116 onwards related presentions and mission documentation available on L2 ** Daily MMT/MER STS-116 information on L2 helped collate this article.

**LIVE news updates on Discovery STS-116 – FOR EACH FLIGHT DAY** – 100s of live updates each flight day, including images and videos, all interactive.

Weather constraints are the defining factor for determining Discovery’s destination, which continue to place White Sands at the top of the list at the end of Thursday. However, the preferred option of the Kennedy Space Center (KSC) has by no means been ruled out.

A change in the forecast is hoped for, given KSC would allow Discovery to return to her Orbiting Processing Facility (OPF) the same day, as opposed to what could be up to 60 days, if she lands at White Sands.

Edwards Air Force Base in California is the other option open to NASA on Friday, which is also preferred to White Sands, due to the on-site facilities and past experience in returning an orbiter back to KSC, around a week after landing.

White Sands holds a number of issues for Discovery, as noted in a previous article on this site. However, deputy shuttle manager John Shannon noted that the ability to care for the orbiter in New Mexico is solidifying, as managers continued to work mitigation plans during all of Friday.

‘Landing at White Sands is no concern to us at all. The concern with White Sands is with the turnaround facilities. We don’t have the large mate/de-mate facility that we use to lift the orbiter on to the back of the Shuttle Carrier Aircraft, and we don’t have as much equipment out there to service the vehicle.

‘As far as a landing site, it’s one of the best places you’d want to land.

Shannon’s comments were more positive than the memos that were being sent to the MMT (Management Mission Team) by NASA managers earlier in the day, which made a point of noting the freezing temperatures – and the relevance of those conditions to Discovery herself.

‘In my conversation with (name deleted) this morning, the landing will be Friday. A remote chance for a Saturday landing but according to the ‘rules’, Saturday is only if there is a systems problem, not weather,’ noted one memo acquired by this site.

‘There is a very good chance it will be at White Sands and everyone is scrambling because they (White Sands) do not have the equipment to safe the orbiter and temperatures are freezing or below.

‘Plus the orbiter will be there for at least a month until they can get the ferry equipment there to ferry the orbiter to KSC. It’s not a great situation but possibly no choice in the matter. We will wait and see and pray for a break in the weather.’

Another memo, from the MMT, emphasized the issues relating to Discovery’s thrusters and hydrazine/water lines in such freezing conditions.

‘Northrup Discussion – KSC ground operations personnel summarized the capabilities available at Northrup. The community is confident that the orbiter can safely land at Northrup and there are adequate faculties to egress the crew,’ noted the memo.

‘One of the main concerns with a landing at Northrup is how it affects the post-processing of the vehicle.

‘During the extended period where the orbiter would remain at Northrup, the orbiter could be exposed to low temperatures that would increase the chances of leaking thrusters and freezing hydrazine/water lines.

This concern extrapolates into some additional risk to the ground personnel that are post-processing the orbiter.

‘After taking a poll, the MMT team unanimously agreed that crew safety will not be traded at the expense of vehicle turnaround concerns.’

On the positive side, Shannon pointed out that the weather at the White Sands Space Harbor is now forecast to stay above freezing for Discovery’s first overnight stay, allowing for extra time for KSC equipment to be shipped and installed in New Mexico.

‘We are taking some backup equipment from KSC, which are on two C-17s leaving Florida later today (Thursday), this will include a nitrogen purge unit and a power unit to protect the vehicle (from the freezing temperatures) – plus around 60 workers to protect her.

‘If we land there, I feel we’ll be in great shape on the vehicle, but the turnaround is going to take a little bit longer. I wouldn’t be surprised if we were out there for 45-60 days while we get the crane set up to do a safe lift on to the Shuttle Carrier Aircraft.’

Should the weather improve in Florida, Discovery’s first attempt will be given a green light to land at KSC. That would see a go being given for the deorbit burn at 2:49pm Eastern, resulting in a landing at KSC at 3:56pm Eastern.

Should that attempt prove to be constrained by the weather, Edwards, then White Sands, will be considered for potential landing opportunities.

Meanwhile, as expected, Friday’s landing received the official go-ahead, following the confirmation that Discovery’s Thermal Protection System (TPS) is in great shape, resulting from the Late Inspection evaluations by the MMT.

The scheduled checkouts of Discovery’s systems – that are required for returning home – also proved to be in perfect working order.

‘This was another just another fantastic day in space for Discovery. The crew are in great spirits and they are ready to land the vehicle,’ said Norm Knight Entry Flight Director for STS-116. ‘The best news of the day is the Late Inspection results came back and the MMT cleared the vehicle for entry.

‘The primary aim for today was to check the vehicle out. We performed the flight control system checkout and we also performed the RCS (Reaction Control System) hotfire. Both of those activities were completed, and both were nominal.

‘This wasn’t a surprise for us as the vehicle has been performing extremely well on this mission.’

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