NASA Puts One Space Station Propulsion Vehicle on Ice While Moving Ahead with Another

According to a story in the week’s Space News, and sources who have spoken with SpaceRef, it would seem that NASA has decided to direct the Naval Research Laboratory (NRL) to cease activity on the Interim Control Module (ICM), a spacecraft designed to provide Space Station contingency reboost capabilities in case of a problem with Russia’s ability to provide the Service Module and/or Progress vehicles. The need for the ICM arose several years ago as delays in Russia’s ability to deliver hardware began to concern Congress.

Now that the Service Module is on orbit, NASA feels that Russia can make its propellant deliveries to the ISS and that such a contingency is not needed for immediate use. As such, NASA wants the NRL to put the entire program in mothballs and will pay it only $50,000 a month to do so. No staff would be retained under this option. After turning down alternatives that would have made the spacecraft more readily available, NASA issued a stop work order tot he NRL on 30 October 2000.

There is some difference in opinion as to how long it would take to actually put an ICM on the launch pad once the need to do so was formally stated. Space News refers to an internal memo which states that this would take 2 years. SpaceRef sources suggest that this could happen much more quickly. According to NASA sources, under the plan NASA has worked out with NRL, The ICM will be stowed in near-flight ready condition such that the program requirement to be ready to fly within 180 days can still be met.

Meanwhile, as NASA decides to put the ICM option on hold, Russia has decided to delay another Progress launch to the ISS – this time from December 2000 until February 2001. This will require the Shuttle to step in and take on some of the ISS reboost activities. The net result will be a hit on shuttle payload upmass. NASA says it will come out of the mass assigned to science payloads. This recent delay notwithstanding, NASA still expresses confidence in Russia’s ability to meet its ISS commitments.

The ICM that NASA and NRL are now building is not the fancy spacecraft first considered – it is no longer an independent spacecraft being used to assist the ISS. The ICM no longer has solar panels and must draw all power from the ISS. The software has been simplified or “descoped” substantially and its interface with the ISS is more basic. Instead of being an autonomous vehicle, NASA’s ICM it is now just tanks, structure, fuel lines, with a passive thermal system, rocket engines, and a firm wire controller.

There was a “red team” review activity at NASA MSFC in May of 2000 designed to address all of the issues and concerns with the ICM. At first, the team thought they’d try to fly the ICM close to the exiting ISS-4A mission on a special mission: ISS-2a.1. However, there were some cg (center of gravity) concerns with the ISS so that plan was shelved. The team then worked toward an option wherein the ICM would fly on ISS-2A.1 sometime around the previously manifested ISS-7A mission. The cg problem was pretty much the same in this situation. Further review showed that the ICM would not be needed this late in the assembly sequence.

Meanwhile, the U.S. Propulsion Module (USPM) activity continues to move ahead. The USPM is a long term solution designed to provide reboost capability independent of that provided by the Russian Service Module. Unlike the ICM which was not designed to be refueled in orbit, the USPM would have all of the capabilities currently provided by the Service Module – without the pressurized living volume.

After several years of design activities led by Boeing had led to dramatically escalating costs and scheduled delays, NASA decided that the activity needed to be totally overhauled. A series of reviews followed in 2000 from which a new concept for the USPM emerged. This new concept seeks to reuse a piece of ISS hardware that had been placed into long term storage.

The current plan is to utilize the Node Structural Test Article (STA) which has been in storage at NASA MSFC and hang two propulsion packages off of it using passive CBMs at two of the Node’s radial ports. Once referred to as “Node X”, this spare node is now called “Node 4”. Outfitting of Node 4 will be done in-house at NASA MSFC.

NASA will release an RFP in early 2001 soliciting propulsion elements for the USPM. Aerojet, Lockheed Martin, and Boeing are expected to be among those bidding for the for the propulsion package.

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